research paper about marijuana legalization

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• Subst Abuse
• PMC10176789

The Impact of Recreational Cannabis Legalization on Cannabis Use and Associated Outcomes: A Systematic Review

Kyra n farrelly.

1 Department of Psychology, York University, Toronto, ON, Canada

2 Peter Boris Centre for Addictions Research, St. Joseph’s Healthcare Hamilton, McMaster University, Hamilton, ON, Canada

Jeffrey D Wardell

3 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, ON, Canada

4 Department of Psychiatry, University of Toronto, Toronto, ON, Canada

Emma Marsden

Molly l scarfe, peter najdzionek, jasmine turna.

5 Michael G. DeGroote Centre for Medicinal Cannabis Research, McMaster University & St. Joseph’s Healthcare Hamilton, Hamilton, ON, Canada

James MacKillop

6 Homewood Research Institute, Guelph, ON, Canada

Background:

Recreational cannabis legalization has become more prevalent over the past decade, increasing the need to understand its impact on downstream health-related outcomes. Although prior reviews have broadly summarized research on cannabis liberalization policies (including decriminalization and medical legalization), directed efforts are needed to synthesize the more recent research that focuses on recreational cannabis legalization specifically. Thus, the current review summarizes existing studies using longitudinal designs to evaluate impacts of recreational cannabis legalization on cannabis use and related outcomes.

A comprehensive bibliographic search strategy revealed 61 studies published from 2016 to 2022 that met criteria for inclusion. The studies were predominantly from the United States (66.2%) and primarily utilized self-report data (for cannabis use and attitudes) or administrative data (for health-related, driving, and crime outcomes).

Five main categories of outcomes were identified through the review: cannabis and other substance use, attitudes toward cannabis, health-care utilization, driving-related outcomes, and crime-related outcomes. The extant literature revealed mixed findings, including some evidence of negative consequences of legalization (such as increased young adult use, cannabis-related healthcare visits, and impaired driving) and some evidence for minimal impacts (such as little change in adolescent cannabis use rates, substance use rates, and mixed evidence for changes in cannabis-related attitudes).

Conclusions:

Overall, the existing literature reveals a number of negative consequences of legalization, although the findings are mixed and generally do not suggest large magnitude short-term impacts. The review highlights the need for more systematic investigation, particularly across a greater diversity of geographic regions.

Introduction

Cannabis is one of the most widely used substances globally, with nearly 2.5% of the world population reporting past year cannabis use. 1 Cannabis use rates are particularly high in North America. In the U.S., 45% of individuals reported ever using cannabis and 18% reported using at least once annually in 2019. 2 , 3 In Canada, approximately 21% of people reported cannabis use in the past year use in 2019. 4 In terms of cannabis use disorder (CUD), a psychiatric disorder defined by clinically significant impairment in daily life due to cannabis use, 5 ~5.1% of the U.S. population ages 12+ years met criteria in 2020, with ~13.5% of individuals ages 18 to 25 years meeting criteria. 6

Overall, rates of cannabis use have shown long-term increasing trends among several age groups in North America. 7 - 9 Moreover, research has revealed recent cannabis use increases in at risk populations, such as individuals with depression and pregnant women. 10 , 11 Parallel to increased cannabis use over time, rates of cannabis-related consequences have also increased across Canada and the U.S., including cannabis dependence and CUD, 8 , 12 crime rates (eg, increased possession charges), 8 and cannabis-impaired driving (and, lower perception of impairment and risk from cannabis use). 11 , 13 , 14 Further, cannabis use poses a risk for early-onset or use during adolescence as there is evidence that cannabis use in adolescence is linked with poorer cognitive performance, psychotic disorders, and increased risk of mood and addictive disorders. 15 With the rates of negative consequences from cannabis use increasing, particularly in North America where cannabis has become legal in many parts of the US and all of Canada, understanding the role of cannabis legalization in these changes is crucial to inform ongoing changes in cannabis policies worldwide.

The legal status of cannabis varies widely across countries and regions. Although cannabis is largely illegal at the global level, policies surrounding cannabis use are becoming steadily liberalized. Decriminalization (reduced penalties for self-use but not distribution) is more widespread worldwide, including in the Netherlands, Portugal, and parts of Australia. Medical legalization is also seen in Peru, Germany, New Zealand, the Netherlands and across many U.S. states. To date, Canada, Uruguay, and Malta are the only 3 countries to legalize recreational cannabis use at the national level. Further, individual U.S. states began legalizing recreational cannabis in 2012, with nearly half of U.S. states having legalized recreational cannabis by 2023. As national and subnational recreational legalization continues to gain support and take effect, understanding the consequences of such major regulatory changes is crucial to informing ongoing policy changes.

There are arguments both for and against recreational cannabis legalization (RCL). Common pro-legalization arguments involve increasing regulatory control over product distribution, weakening organized crime, reducing burden and inequality in the criminal justice system, and generating economic benefits such as tax revenues and commercial activity. 16 Furthermore, as cannabis obtained from illicit markets is of varying and unknown potency, 17 cannabis legalization may help better regulate the potency and quality of cannabis products. 18 On the other hand, there are anti-legalization arguments such as the possibility of legalization leading to increased use among youth and increased cannabis-impaired driving. 16 A nationally representative survey in the U.S. found that pro-legalization arguments were perceived to be more persuasive than public health anti-legalization arguments in a U.S. nationally representative survey, 19 suggesting policymaker concerns regarding RCL do not seem to hold as much weight in the general public. However, while research may be increasing surrounding the impacts of RCL, the general consensus of if RCL leads to more positive or negative consequences is unclear.

With RCL becoming more prevalent globally, the impacts it may have on a variety of health-related outcomes are of critical importance. Prevalence of cannabis use is of course a relevant issue, with many concerned that RCL will cause significant spikes in rates of cannabis use for a variety of groups, including youth. However, current studies have revealed mixed evidence in the U.S., 20 , 21 thus there is a need to synthesize the extant literature to better understand the balance of evidence and potential impacts of RCL across different samples and more diverse geographic areas. Another common question about RCL is whether it will result in changes in attitudes toward cannabis. These changes are of interest as they might forecast changes in consumption or adverse consequences. Similarly, there are concerns surrounding RCL and potential spill-over effects that may influence rates of alcohol and other substance use. 22 Thus, there remains a need to examine any changes in use of other substance use when studying effects of RCL.

Beyond changes in cannabis and other substance use and attitudes, health-related impacts of RCL are important to consider as there are links between cannabis use and adverse physical and mental health consequences (eg, respiratory and cardiovascular diseases, psychosis). 23 Additionally, emergency service utilization associated with cannabis consumption is a frequent concern associated with RCL, particularly due to the spikes in admissions following RCL in Colorado. 24 However, the rates of cannabis-related emergency service admissions more globally (eg, in legal countries like Canada and Uruguay) have not been fully integrated into summaries of the current literature. Finally, another health-related consequence of RCL is potential impacts on opioid use. While opioid-related outcomes can fall into substance use, they are considered health-related for this review as much of the discussion surrounding RCL and opioids involve cannabis substituting opioid use for medicinal reasons or using cannabis as an alternate to prescription opioids in the healthcare system. The current opioid crisis is a global public health problem with serious consequences. While there is evidence that medicinal cannabis may reduce prescription opioid use 25 and that cannabis may be a substitute for opioid use, 26 the role of recreational cannabis legalization should also be examined as the 2 forms of cannabis use are not interchangable 27 and have shown unique associations with prescription drug use. 28 Thus, there is a need to better understand how and if RCL has protective or negative consequences on opioid-related outcomes.

Due to the impairing effects of cannabis on driving abilities and the relationship with motor vehicle accidents, 29 another important question surrounding RCL is how these policy changes could result in adverse driving-related outcomes. An understanding of how RCL could influence impaired driving prevalence is needed to give insight into how much emphasis jurisdictions should put on impaired driving rates when considering RCL implementation. A final consequence of RCL that is often debated but requires a deeper understanding is how it impacts cannabis-related arrest rates. Cannabis-related arrests currently pose a significant burden on the U.S. and Canadian justice system. 30 , 31 Theoretically, RCL may ease the strain seen on the justice system and have positive trickle-down effects on criminal-related infrastructure. However, the overall implications of RCL on arrest rates is not well understood and requires a systematic evaluation. With the large number of RCL associated outcomes there remains a need to synthesize the current evidence surrounding how RCL can impact cannabis use and other relevant outcomes

Present review

Currently, no reviews have systematically evaluated how RCL is associated with cannabis-use changes across a variety of age groups as well as implications on other person- or health-related outcomes. The present review aims to fill an important gap in the literature by summarizing the burgeoning research examining a broad range of consequences of RCL across the various jurisdictions that have implemented RCL to date. Although previous reviews have considered the implications of RCL, 32 , 33 there has recently been a dramatic increase in studies in response to more recent changes in recreational cannabis use policies, requiring additional efforts to synthesize the latest research. Further, many reviews focus on specific outcomes (eg, parenting, 34 adolescent use 35 ). There remains a need to systematically summarize how RCL has impacted a variety of health-related outcomes to develop a more comprehensive understanding of the more negative and positive outcomes of RCL. While a few reviews have examined a broad range of outcomes such as cannabis use, related problems, and public health implications, 32 , 33 some reviews have been limited to studies from a single country or published in a narrow time window. 32 Thus, a broader review is necessary to examine multiple types of outcomes from studies in various geographic regions. Additionally, a substantial amount of the current literature examining the impact of RCL relies on cross-sectional designs (eg, comparing across jurisdictions with vs without recreational legalization) which severely limit any conclusions about causal associations. Thus, given its breadth, the current systematic review is more methodologically selective by including only studies with more rigorous designs (such as longitudinal cohort studies), which provide stronger evidence regarding the effects of RCL. In sum, the aim of the current review was to characterize the health-related impacts of RCL, including changes in these outcomes in either a positive or negative direction.

The review is compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 36 ). Full-text extraction was initiated immediately following article search, therefore the protocol was not registered with PROSPERO. Relevant articles on cannabis legalization were principally identified using the Boolean search terms (“cannabis” OR “marijuana” OR “THC” OR “marihuana”) AND “legalization” AND (“recreational” OR “non-medical” OR “nonmedical”) AND (“longitudinal” OR “pre-post” OR “prospective” OR “timeseries” OR “cohort”). The search was conducted using PubMed/MEDLINE, EMBASE, and PsycINFO through November 2022. Relevant studies identified through secondary means (eg, prior knowledge of a relevant publication, articles brought to the authors’ attention) were also included for screening. Titles and abstracts resulting from the initial search were screened in Covidence (Veritas Health Innovation Inc) by 2 reviewers for suitability for full-text review and final inclusion. Conflicts were discussed by both reviewers and a final decision was made by consensus. Following screening, reviewers read and extracted relevant data. To be included, an article was required to meet the following criteria: (i) an original empirical research article published in a peer-reviewed journal; (ii) written in (or available in) English; (iii) RCL serves as an independent variable; (iv) quantitative study design that clearly permitted the evaluation of the role of RCL with a more rigorous non-cross-sectional study design (eg, pre- vs post-legalization, longitudinal, cohort, interrupted time series, etc.); and (v) reports on health-related outcomes (ie, changes in consumption or attitudes, as opposed to changes in price or potency).

RCL related outcomes that were considered were those specifically involving the behavior, perceptions, and health of individuals. Population-level outcomes (eg, health-care utilization or impaired driving) were considered eligible for inclusion as they involve the impacts that legalization has on individual behavior. Thus, economic- or product-level outcomes that do not involve individual behavior (eg, cannabis prices over time, changes in cannabis strain potency) were considered out of scope. The outcome groups were not decided ahead of time and instead 5 main themes in outcomes emerged from our search and were organized into categories for ease of presentation due to the large number of studies included.

Studies that examined medicinal cannabis legalization or decriminalization without recreational legalization, and studies using exclusively a cross-sectional design were excluded as they were outside the scope of the current review. The study also excluded articles that classified RCL as the passing of legal sales rather than implementation of RCL itself as RCL is often distinct from introduction of legal sales, or commercialization. Thus, we excluded studies examining commercialization as they were outside the scope of the current review.

Characteristics of the literature

The search revealed 65 relevant articles examining RCL and related outcomes (see Figure 1 ). There were 5 main themes established: cannabis use and other substance use behaviors ( k  = 28), attitudes toward cannabis ( k  = 9), health-related outcomes ( k  = 33), driving related impacts ( k  = 6), and crime-related outcomes ( k  = 3). Studies with overlapping themes were included in all appropriate sections. Most studies (66.2%) involved a U.S. sample, 32.3% examined outcomes in Canada, and 1.5% came from Uruguay. Regarding study design, the majority (46.2%) utilized archival administrative data (ie, hospital/health information across multiple time points in one jurisdiction) followed by cohort studies (18.5%). The use of administrative data was primarily used in studies examining health-related outcomes, such as emergency department utilization. Studies examining cannabis use or attitudes over time predominantly used survey data. Finally, both driving and crime related outcome studies primarily reported findings with administrative data.

Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) study flow diagram.

Changes in cannabis and other substance use

Cannabis and other substance use changes represented the second largest number of studies, with 28 articles identified. Studies examining changes in cannabis use behaviors were divided by subpopulation (ie, adolescents, young adults, general population adults, clinical populations, and maternal use; see Table 1 ). Finally, we separately summarized studies reporting changes in concurrent use of other substances, and routes of cannabis administration.

Studies investigating the role of recreational cannabis legalization on cannabis and other substance consumption.

Author, author of article; Year, publication year of article; Location, jurisdiction article data was collected in; Date of Legalization, year legalization was enacted in jurisdiction; Sample, total N of article sample; RCL, Recreational Cannabis Legalization.

Cannabis use changes in adolescents (~12-17)

Ten studies examined changes in cannabis use among adolescents and found that changes in the rates of use were inconsistent following RCL. Gunadi et al 37 found an association between RCL and more pronounced transition from non-use to cannabis use when compared to states with no legalization and those with medical cannabis legalization ( P  ⩽ .001) combined, but not when compared to states with medical cannabis legalization only. Another study found that in states with RCL adolescents who never used cannabis but used e-cigarettes were more likely to use cannabis at follow-up than those living in states without RCL (aOR = 18.39, 95% CI: 4.25-79.68vs aOR = 5.09, 95% CI: 2.86-9.07, respectively) suggesting a risk of cannabis initiation among legal states. 38 Among adolescents reporting recent alcohol and cannabis co-use, one study found a significant increase in the frequency of past 30-day cannabis use following RCL ( b  = 0.36, SE = 0.07, P  ⩽ .001). 39 In a Canadian study using a repeated cross-sectional design as well as a longitudinal design to examine changes in cannabis use, results revealed that adolescents had increased odds of ever using cannabis in the year following RCL in the cross-sectional data ( P  = .009). 40 However, the longitudinal sample revealed no significant differences in the odds of ever use, current use, and regular use of cannabis post-legalization. There is also evidence of RCL impacts on adolescent cannabis use consequences, as a Washington study found a significant indirect effect of RCL on cannabis consequences through perceived risk as a mediator ( B  = 0.37, P  ⩽ .001). 41

On top of the above evidence, there were multiple studies examining cannabis use changes over time among adolescents in Washington and Oregon that found higher rates of cannabis use associated with cohorts examined during RCL compared to non-legal cohorts, 42 - 44 although the differences across legal cohorts were not significant in all cases. 42 Furthermore, in another study, RCL did not impact initiation of use, but for current users the RCL group had significantly greater increased rates of cannabis use compared to the pre-RCL group (RR = 1.26, 95% CI = 1.10, 1.45). 43 For the final study, cannabis use increased in the post-RCL group but patterns of use (frequency; daily vs weekly use) were similar across groups. 44 Overall, the preceding 8 studies reveal some evidence that RCL was associated with increasing rates of cannabis use in adolescent. However, 5 studies point to some inconsistent associations of RCL and cannabis use and suggest that overall relationship of RCL and adolescent cannabis as mixed.

Three studies add to these inconsistent findings and point to lack of an association between RCL and changes in cannabis use among adolescents. Two studies found no significant increase in the frequency of or prevalence of cannabis use following RCL. 41 , 45 Finally, a study examining trends of adolescent cannabis use and associations with period effects (ie, external world events that could influence use) suggests laws and regulations associated with RCL were not associated with cannabis use changes. 46 The current research reveals conflicting evidence about the role of RCL on adolescent cannabis use.

Cannabis use changes in young adults (~18-25)

Young adulthood, typically defined as ages 18 to 25 and also known as emerging adulthood, is commonly associated with decreased parental supervision, increased availability of substances, and greater substance experimentation making it a key developmental period for the onset of cannabis use. 47 Four studies examined the impact of RCL on cannabis use among young adults, 2 of which found significant associations between RCL and increased cannabis use in college students. 47 , 48 Barker and Moreno 48 found the rate of students ever using cannabis did not change. However, in those who had used cannabis prior to RCL, the proportion of students using in the past 28-days increased faster following RCL in Washington (legal-state) when compared with the rate of increase in Wisconsin (non-legal state; P  ⩽ .001). 48 Further, in college students from Oregon, rates of cannabis use increased significantly from before to after RCL ( P  = .0002). 47 Another study looked at changes in cannabis use in a sample of young adults from the U.S. who had never vaped cannabis at the time of recruitment. 49 Results revealed that cannabis use in the past year did not differ in states with or without RCL, although, those living in states with RCL did show a larger increase in rates of cannabis vaping across time, compared to those in non-RCL states. Finally, in a sample of youth from Oregon and Washington, RCL predicted a higher likelihood of past-year cannabis use ( P  = .001). 50 In contrast to the adolescent literature, studies examining cannabis use in young adult samples fairly consistently point to an association between RCL and increasing rates of cannabis use.

Cannabis use changes in general population adults

Five studies examined changes in cannabis use in adults (without further age subclassification) associated with RCL. Four of these studies suggested higher rates of cannabis use in adults for RCL jurisdictions compared to non-legal states post-RCL, or increased use following RCL. 37 , 45 , 51 , 52 Past 30-day cannabis use increased significantly 1-month post-RCL and remained elevated 6-months post-RCL (ps = 0.01) in a sample of adults from California. 51 Another study found an association between RCL and transition from non-users to cannabis users and non-users to weekly users when compared to states with no medical legalization or RCL ( P  ⩽ .001) and states with no legalization combined with those with medical cannabis legalization ( P  ⩽ .001). 37 Meanwhile, in Canada, a significant increase in prevalence of cannabis use was observed following RCL. 45 Additionally, in those reporting no cannabis use prior to RCL in Canada, there were significant increases in cannabis use frequency, quantity of cannabis used, and severity of cannabis misuse following RCL. 52 The opposite pattern was seen for those reporting cannabis use prior to RCL, with significant decreases in frequency of use, quantity, and misuse. 52 However, not all studies found RCL was associated with increased cannabis use. For instance, a repeated cross-sectional study of adult in the U.S. found no association between RCL and frequency of cannabis use. 53

A benefit of the extant literature examining general population cannabis use is that it covers a variety of jurisdictions and study designs, albeit with some heterogeneity and mixed findings. On balance, the evidence within the current literature, generally suggests an increase in cannabis use for adults in the general population following RCL with 80% of the reviewed studies supporting this conclusion.

Maternal use

Three studies examined whether rates of cannabis use during pregnancy have increased following RCL. Two studies suggested increased cannabis use during pregnancy associated with RCL. In one study urine screen-detected cannabis use during pregnancy increased from 6% to 11% following RCL in California ( P  = .05). 54 Another study in a sample of women participating in an intensive case management program for heavy alcohol and/or drug use during pregnancy, examined cannabis use among those exiting from the program before versus after RCL. Findings revealed women exiting after RCL were more likely to report using cannabis in the 30 days prior to exit compared to those pre-RCL (OR = 2.1, P  ⩽ .0001). 55 One study revealed no significant difference in cannabis or alcohol use associated with RCL in women living with HIV during pregnancy or the postpartum period. 56 Overall, the evidence from these three studies suggests there may be increases in perinatal cannabis use following RCL, but the small number of studies and unique features of the samples suggests a need for more research.

Clinical populations use

Six studies examined cannabis use in clinical populations. One study investigated use and trauma admissions for adults and pediatric patients in California. 57 Results showed an increase in adult trauma patients with THC+ urine tests from pre- to post-RCL (9.4% to 11.0%; P  = .001), but no difference for pediatric trauma patients. A study based in Colorado and Washington, found that cannabis use rates in inflammatory bowel disease patients significantly increased from 107 users to 413 ( P  ⩽ .001) pre to post-RCL. 58 A Canada-based study of women with moderate-to-severe pelvic pain found an increase in the prevalence of current cannabis use following RCL (13.3% to 21.5%; P  ⩽ .001). 59 Another Canadian study showed an increase in the prevalence of current cannabis use after RCL among cancer patients (23.1% to 29.1%; P  ⩽ .01). 60 Finally, two studies examined changes in cannabis use among individuals receiving treatment for a substance use disorder. In a sample of Canadian youth in an outpatient addictions treatment program, there was no change in the rate of cannabis use following RCL. 61 Further, in a sample of individuals receiving treatment for opioid use disorder, cannabis use was compared for those recruited 6 months before or after RCL with no significant changes in the prevalence or frequency of self-reported ( P  = .348 and P  = .896, respectively) or urine screen-detected ( P  = .087 and P  = .638, respectively) cannabis use following RCL. 62 Although these studies only represent a small number of observations, their findings do reveal associations between RCL and increasing cannabis use within some clinical samples.

Changes in polysubstance and other substance use

One study examined simultaneous cannabis and alcohol use among 7th, 9th, and 11th grade students in the U.S. 39 This study found that RCL was associated with a 6% increase in the odds of past 30-day alcohol and cannabis co-use. The association was even stronger in students with past 30-day alcohol use and heavy drinking. However, among past 30-day cannabis users, RCL was associated with a 24% reduction in co-use. This study suggests at least a modest association between RCL and concurrent cannabis and alcohol use among adolescents.

Numerous studies examined changes of alcohol and other substance use pre to post RCL. With regard to alcohol, one study from Colorado and Washington found a decrease in alcohol consumption among adolescents following RCL, 42 whereas another Washington study found RCL predicted a higher likelihood of alcohol use among youth. 50 A Canadian study also found no significant effect of RCL on rates of alcohol or illicit drug use among youth. 61 Finally, in a sample of trauma patients in California the findings around changes in substance use were mixed. 57 In adult patients, the rates of positive screens for alcohol, opiates, methamphetamine, benzodiazepine/barbiturate, and MDMA did not change following RCL, but there was an increase in positive screens for cocaine. In pediatric patients, increases were seen in positive screens for benzodiazepine/barbiturate, but positive screens for alcohol, opiates, methamphetamine, and cocaine did not change. 57 The current evidence is divided on whether RCL is associated with increased alcohol and other substance use, with 40% of studies finding an association and 60% not observing one or finding mixed results.

In the case of cigarettes, Mason et al 42 did find significant cohort effects, where the post-RCL cohort was less likely to consume cigarettes compared to the pre-RCL one (Coefficient: − 2.16, P  ⩽ .01). However, these findings were not echoed in more recent studies. Lack of an effect for cigarette use is supported by an Oregon study that found RCL was not associated with college student’s cigarette use. 47 Similarly, RCL was not significantly associated with past-year cigarette use in a sample of young adults from Oregon and Washington. 50 On balance, there is little evidence that RCL is linked with changes in cigarette smoking.

Route of administration

The increase in smoke-free alternative routes of cannabis administration (eg, vaping and oral ingestion of edibles) 63 , 64 make method of cannabis consumption an important topic to understand in the context of RCL. Two studies examined differences in route of cannabis consumption as a function of cannabis policy. One study examined changes in the number of different modes of cannabis use reported by high school students in Canada. 65 Results showed that from pre-to-post RCL 31.3% of students maintained a single mode of use, 14.3% continued to use cannabis in multiple forms, while 42.3% expanded from a single mode to multiple modes of administration and 12.1% reduced the number of modes they used. Another study found that smoking, vaping, and edibles (in that order) were the most frequent modes of cannabis use pre- and post-RCL in California, suggesting minimal impact of RCL on mode of cannabis use. 51 However, the least common mode of cannabis use was blunts, which did decline following RCL (13.5%-4.3%). 51 Overall, the evidence suggests RCL may be associated with changes in modes of cannabis consumption, but as the evidence is only from two studies there still remains a need for more studies examining RCL and cannabis route of administration.

Nine studies examined RCL and cannabis attitudes (see Table 2 ). Regarding cannabis use intentions, one U.S. study found that for both a non-RCL state and a state that underwent RCL, intention to use in young adults significantly increased post-RCL, suggesting a lack of RCL specific effect, 48 and that aside from the very first time point, there were no significant differences between the states in intention to use. Further, attitudes and willingness to use cannabis, between the RCL and non-RCL state remained similar overtime ( P s ⩾ .05), although both states reported significantly more positive attitudes toward cannabis following RCL ( P  ⩽ .001). 48 However, another study U.S. from found differences in adolescent use intentions across RCL, whereby those in the RCL cohort in jurisdictions that allowed sales were less likely to increase intent to use cannabis ( P  = .04), but the RCL cohort without sales were more likely to increase intent to use ( P  = .02). 43 The pre-RCL cohort in communities that opted out of sales were also less likely to increase willingness to use compared to the cohort with legal sales ( P  = .02). 43 Both studies reveal contrasting findings surrounding RCL’s relationship with cannabis use intentions and willingness to use.

Studies examining recreational cannabis legalization and attitudes surrounding cannabis.

Looking at cannabis use motives, one study found a non-significant increase in recreational motives for cannabis use post-RCL. 60 Similarly following RCL in Canada, 24% of individuals previously reporting cannabis use exclusively for medical purposes declared using for both medical and non-medical purposes following RCL, and 24% declared use for non-medical purposes only, 66 suggesting RCL can influence recreational/nonmedicinal motivations for cannabis use among those who previously only used for medical reasons.

In studies examining perceived risk and perceptions of cannabis use, one U.S. study found an indirect effect between RCL and increased consequences of use in adolescents through higher perceived risk ( P  ⩽ .001), but no association with frequency of use. 41 Another U.S. study revealed mixed results and found that RCL was not associated with perceived harm of use in youth. 50 Further, youth in one study did not report differences in perceptions of safety of cannabis, ease of accessing cannabis use or on concealing their use from authority, 61 which contrasts with another study finding increased reports of problems accessing cannabis post-RCL ( P  ⩽ .01). 60 Regarding health perceptions, a California study found that cannabis use was perceived as more beneficial for mental health, physical health, and wellbeing in adults at 6 months post-RCL compared to pre-RCL and 1-month post-RCL ( P  = .02). 51 Mental health perceptions of cannabis use increased from being perceived as “slightly harmful” pre-RCL to perceived as “slightly beneficial” at 6 months post-RCL. 51 However, in a sample of treatment seeking individuals with an opioid use disorder, the vast majority of participants reported beliefs that RCL would not impact their cannabis use, with no difference in beliefs pre- to post-RCL (85.9% reported belief it would have no impact pre-RCL and 85.7%, post-RCL). 62 The combined results of the studies suggest potential associations of RCL with risk and benefit perceptions of cannabis use, however as 55% of studies suggest a lack of or inconsistent association with RCL, on balance the literature on RCL’s impact on cannabis attitudes is mixed.

Health-related outcomes

We identified 33 articles that examined various health-related outcomes associated with RCL (see Table 3 ). The largest number involved hospital utilization (ie, seeking emergency services for cannabis-related problems such as unintentional exposure, CUD, and other harms). Other health-care outcomes included opioid-related harms, mental health variables, and adverse birth outcomes.

Studies investigating the relationship of recreational cannabis legalization and health-related outcomes.

Author, Author of article; Year, Publication year of article; Location, Jurisdiction article data was collected in; Date of Legalization, Year legalization was enacted in jurisdiction; Sample, Total N of article sample; CDC, Center for Disease Prevention; WONDER, Wide-Ranging Online Data for Epidemiologic Research; RCL, Recreational Cannabis Legalization.

Emergency service utilization

Seventeen studies examined the association between RCL and use of emergency services related to cannabis (eg, hospital visits, calls to regional poison centers). Regarding emergency service rates in youth, a Colorado study found the rate of pediatric cannabis-related emergency visits increased pre- to post-RCL ( P  ⩽ .0001). 67 Similarly, cannabis-related visits requiring further evaluation in youth also increased. 67 This increasing need for emergency service related to cannabis exposure in youth following RCL was supported in 4 other U.S. studies. 68 - 71 A Canadian study supported the U.S. studies, finding a 2.6 increase in children admissions for cannabis poisonings post-RCL. 72 In contrast, overall pediatric emergency department visits did not change from pre- to post-RCL in Alberta, Canada, 73 but there was a non-significant increase of the rate and proportion of children under 12 presenting to the emergency department. However, unintentional cannabis ingestion did increase post-RCL for children under 12 (95% CI: 1.05-1.47) and older adolescents (1.48, 95% CI: 1.21-1.81). 74 Taken together, these studies do suggest a risk for increasing cannabis-related emergency visits in youth following RCL, with 75% of studies finding an association between RCL and increasing emergency service rates in youth.

There is also evidence of increased hospital utilization in adults following RCL. Five studies found evidence of increased emergency service utilization or poison control calls from cannabis exposure associated with RCL in the U.S. and Canada. 24 , 69 , 74 - 76 Finally, a Colorado study saw an increase in cannabis involved pregnancy-related hospital admissions from 2011 to 2018, with notable spikes after 2012 and 2014, timeframes associated with state RCL. 77

However, some evidence points to a lack of association between RCL and emergency service utilization. A chart review in Ontario, Canada found no difference in number of overall cannabis emergency room visits pre- versus post-RCL ( P  = .27). 78 When broken down by age group, visits only increased for those 18 to 29 ( P  = .03). This study also found increases in patients only needing observation ( P  = .002) and fewer needing bloodwork or imaging services (both P s ⩽.05). 78 Further in a California study that found overall cannabis exposure rates were increasing, when breaking these rates down by age there was no significant change in calls for those aged 13 and up, only for those 12 and under. 69 An additional Canadian study found that rates of cannabis related visits were already increasing pre-RCL. 79 Following RCL, although there was a non-significant immediate increase in in cannabis-related emergency visits post-RCL this was followed a significant drop off in the increasing monthly rates seen prior to RCL. 79 Another Canadian study that examined cannabis hyperemesis syndrome emergency visits found that rates of admissions were increasing prior to RCL and the enactment of RCL was not associated with any changes in rates of emergency admissions. 80 As this attenuation occurred in Canada prior to commercialization where strict purchasing policy was in place, it may suggest that having proper regulations in place can prevent the uptick in cannabis-related emergency visits seen in U.S. studies.

Other hospital-related outcomes examined included admissions for cannabis misuse and other substance use exposure. One study found decreasing CUD admission rates over time (95% CI: −4.84, −1.91), with an accelerated, but not significant, decrease in Washington and Colorado (following RCL) compared to the rest of the U.S. 81 In contrast, another study found increased rates of healthcare utilization related to cannabis misuse in Colorado compared to New York and Oklahoma ( P s ⩽.0005). 82 With respect to other substance use, findings revealed post-RCL increases in healthcare utilization in Colorado for alcohol use disorder and overdose injuries but a decrease in chronic pain admissions compared to both controls ( P  ⩽ .05). 82 However, two Canadian studies found the rate of emergency department visits with co-ingestant exposure of alcohol, opioid, cocaine, and unclassified substances in older adolescents and adults decreased post-RCL. 73 , 77 Another Canadian study found no change in cannabis-induced psychosis admissions nor in alcohol- or amphetamine-induced admissions. 83

Finally, three studies examined miscellaneous hospital-related outcomes. A study examining hospital records in Colorado to investigate facial fractures (of significance as substance impairment can increase the risk of accidents) showed a modest but not significant influence of RCL. 84 The only significant increases of facial trauma cases were maxillary and skull base fracture cases ( P s ⩽ .001) suggesting a partial influence of RCL on select trauma fractures. The second study found increased trauma activation (need for additional clinical care in hospital) post-RCL in California ( P  = .01). 57 Moreover, both adult and pediatric trauma patients had increased mortality after RCL ( P  = .03; P  = .02, respectively). 57 The final study examining inflammatory bowel disease (IBD) outcomes in the U.S. found more cannabis users on total parenteral nutrition post-RCL (95% CI: 0.02, 0.89) and lower total hospital costs in users post-RCL (95% CI: −15 717, −1119). 58 No other IBD outcomes differed pre- to post-RCL (eg, mortality, length of stay, need for surgery, abscess incision and drainage).

Overall, these studies point to increased cannabis-related health-care utilization following RCL for youth and pediatrics (75% finding an increase). However, the impact of legalization on adult rates of cannabis-related emergency visits is mixed (44% finding lack of an association with RCL). As findings also varied across different countries (ie, Canada vs the U.S.), it suggests the importance of continually monitoring the role of RCL across different jurisdictions which may have different cannabis regulations in place. These studies also suggest there may be other health consequences associated with RCL. Further research should be done to examine trends of other emergency service use that could be influenced by RCL.

Two studies reported a weak or non-existent effect of RCL on opioid related outcomes. 85 , 86 First, a U.S. administrative study found no association of RCL and opioid prescriptions from orthopedic surgeons. 85 The second study found that, of U.S. states that passed RCL, those that passed policies before 2015 had fewer Schedule III opioid prescriptions ( P  = .003) and fewer total doses prescribed ( P  = .027), 86 but when compared to states with medicinal cannabis legislation, there were no significant differences. However, 3 studies suggested a potential protective effect of RCL, with one study finding a significant decrease for monthly opioid-related deaths following RCL (95% CI: –1.34, –0.03), compared to medical cannabis legalization and prohibition. 87 A Canadian study examining opioid prescription claims also found an accelerated decline in claims for public payers post-RCL compared to declines seen pre-RCL ( P  ⩽ .05). 88 Next a study examining women with pelvic pain found that post-RCL patients were less likely to report daily opioid use, including use for pain ( P  = .026). 59 These studies indicate some inconsistencies in relationships between RCL, opioid prescriptions and use indicators in the current literature, while the literature on balance points to a potential relationship with RCL (60%), the overall evidence is still mixed as 40% of studies support a weak association with RCL.

Adverse birth outcomes

Changes in adverse birth outcomes including small for gestational age (SGA) births, low birth weight, and congenital anomalies were examined in two studies. The first study, which examined birth outcomes in both Colorado and Washington, found that RCL was associated with an increase in congenital anomaly births for both states ( P  ⩽ .001, P  = .01 respectively). 89 Preterm births also significantly increased post-RCL, but only in Colorado ( P  ⩽ .001). Regarding SGA outcomes, there was no association with RCL for either state. 89 Similarly, the second study did find an increase in the prevalence of low birth weight and SGA over time, but RCL was not directly associated with these changes. 90 Although the current literature is small and limited to studies in Washington and Colorado, the evidence suggests minimal changes in adverse birth outcomes following RCL.

Mental health outcomes

Six studies examined mental health related outcomes. A Canadian study examining psychiatric patients did not see a difference in rates of psychotic disorders pre- to post-RCL. 45 Similarly, another Canadian study did not see a difference in hospital admissions with schizophrenia or related codes post-RCL. 83 However, the prevalence of personality disorders and “other” diagnoses was higher post-RCL ( P  = .038). 45 In contrast, another Canadian study found that rates of pediatric cannabis-related emergency visits with co-occurring personality and mood-related co-diagnoses decreased post-RCL among older adolescents. 73 A U.S. study examining the relationship between cannabis use and anxious mood fluctuations in adolescents found RCL had no impact on the association. 91 Similarly, another Canadian study found no difference in mental health symptomology pre- to post-RCL. 61 In contrast, anxiety scores in women with pelvic pain were higher post-RCL compared to pre-RCL ( P  = .036). 59 The small number and mixed findings of these studies, 66.7% finding no association or mixed findings and 33.3% finding an association but in opposite directions, identify a need for further examination of mental health outcomes post-RCL.

Miscellaneous health outcomes

Three studies examined additional health-related outcomes. First, a California study examined changes in medical cannabis status across RCL. Post-RCL, 47.5% of medical cannabis patients remained medical cannabis patients, while 73.8% of non-patients remained so. 92 The transition into medical cannabis patient status post-RCL represented the smallest group (10%). Cannabis legalization was the most reported reason for transition out of medical cannabis patient status (36.2%). 92 Next, a study examining pelvic pain in women found that post-RCL patients reported greater pain catastrophizing ( P  ⩽ .001), less anti-inflammatory ( P  ⩽ .001) and nerve medication use ( P  = .027), but more herbal pain medication use ( P  = .010). 59 Finally, a Canadian study that examined cannabinoids in post-mortem blood samples reported that post-RCL deaths had higher odds of positive cannabis post-mortem screens compared to pre-RCL (95% CI: 1.09-1.73). 93 However, the majority of growth for positive cannabinoid screens took place in the two years prior to RCL implementation. In sub-group analyses, only 25- to 44-year-olds had a significant increase in positive cannabinoid screens (95% CI: 0.05-0.19). Additional post-mortem drug screens found an increase in positive screens for amphetamines ( P  ⩽ .001) and cocaine ( P  = .042) post-RCL. These additional health outcomes demonstrate the wide-ranging health impacts that may be associated with RCL and indicate a continued need to examine the role of RCL on a variety of outcomes.

Driving-related outcomes

Six studies examined rates of motor vehicle accidents and fatalities (see Table 4 ). Two U.S. studies found no statistical difference in fatal motor vehicle collisions associated with RCL. 94 , 95 Further, a California-based study examining THC toxicology screens in motor vehicle accident patients, did find a significant increase in positive screens, but this increase was not associated with implementation of RCL. 96 However, three studies suggest a negative impact of RCL, as one U.S. study found both RCL states and their neighboring states had an increase in motor vehicle fatalities immediately following RCL. 97 Additionally, a Canadian study did find a significant increase in moderately injured drivers with cannabis positive blood screens post-RCL. 98 Finally, a study in Uruguay found RCL was associated with increased immediate fatal crashes for cars, but not motorcycles; further investigation suggested this effect was noticeable in urban areas, but not rural areas. 99 While the overall evidence was inconsistent, current evidence does suggest a modest increase, seen in two studies, in motor vehicle accidents associated with RCL. Further longitudinal research in more jurisdictions is needed to understand the long-term consequences of RCL on motor vehicle accidents.

Studies looking at recreational cannabis legalization and driving related outcomes.

Crime-related outcomes

Three studies explored crime-related outcomes associated with RCL (see Table 5 ). A Washington study examining cannabis-related arrest rates in adults did find significant drops in cannabis-related arrests post-RCL for both 21+ year olds (87% drop; P  ⩽ .001) and 18 to 20-year-olds (46% drop; P  ⩽ .001). 100 However, in another study examining Oregon youth this post-RCL decline for arrests was not seen; cannabis-related allegations in youth actually increased following RCL (28%; 95% CI = 1.14, 1.44). 101 Further, declines in youth allegations prior to RCL ceased after RCL was implemented. In contrast, a Canadian study did find significant decreases in cannabis-related offenses in youth post RCL ( P  ⩽ .001), but rates of property and violent crime did not change across RCL. 102 These studies highlight the diverse effects of RCL across different age groups. However, there remains a need for a more comprehensive evaluation on the role of RCL on cannabis-related arrests.

Studies investigating recreational cannabis legalization and crime related outcomes.

Author, Author of article; Year, Publication year of article; Location, Jurisdiction article data was collected in; Date of Legalization, Year legalization was enacted in jurisdiction; Sample, Total N of article sample; RCL, Recreational Cannabis Legalization.

Notably, two studies also examined race disparities in cannabis-related arrests. For individuals 21+ relative arrest disparities between Black and White individuals grew post-RCL. 100 When looking at 18 to 20-year-olds, cannabis-related arrest rates for Black individuals did slightly decrease, albeit non-significantly, but there was no change in racial disparities. 100 In youth ages 10 to 17, Indigenous and Alaska Native youth were more likely than White youth to receive a cannabis allegation before RCL (95% CI: 2.31, 3.01), with no change in disparity following RCL (95% CI: 2.10, 2.81). 101 On the other hand, Black youth were more likely to receive a cannabis allegation than White youth prior to RCL (95% CI: 1.66, 2.13), but the disparity decreased following RCL (95% CI: 1.06, 1.43). 101 These studies suggest improvements in racial disparities for cannabis-related arrests following RCL, although there ware only two studies and they are limited to the U.S.

The aim of this systematic review was to examine the existing literature on the impacts of RCL on a broad range of behavioral and health-related outcomes. The focus on more rigorous study designs permits greater confidence in the conclusions that can be drawn. The literature revealed five main outcomes that have been examined: cannabis use behaviors, cannabis attitudes, health-related outcomes, driving-related outcomes, and crime-related outcomes. The overall synthesizing of the literature revealed heterogenous and complex effects associated with RCL implementation. The varied findings across behavioral and health related outcomes does not give a clear or categorical answer as to whether RCL is a negative or positive policy change overall. Rather, the review reveals that while a great deal of research is accumulating, there remains a need for more definitive findings on the causal role of RCL on a large variety of substance use, health, attitude-related, driving, and crime-related outcomes.

Overall, studies examining cannabis use behavior revealed evidence for cannabis use increases following RCL, particularly for young adults (100%), peri-natal users (66%), and certain clinical populations (66%). 47 , 54 , 59 While general adult samples had some mixed findings, the majority of studies (80%) suggested increasing rates of use associated with RCL. 51 Of note, the increasing cannabis use rates found in peri-natal and clinical populations are particularly concerning as they do suggest increasing rates in more vulnerable samples where potential adverse consequences of cannabis use are more pressing. 103 However, for both groups the overall literature revealed only a few studies and thus requires further examination. Further, a reason to caution current conclusions surround RCL impacts on substance use, is that there is research suggesting cannabis use rates were increasing prior to RCL in Canada. 104 Thus, there still remains a need to better disentangle causal consequences of RCL on cannabis use rates.

In contrast to studies of adults, studies of adolescents pointed to inconsistent evidence of RCL’s influence on cannabis use rates, 38 , 45 with 60% of studies finding no change or inconsistent evidence surrounding adolescent use following RCL. Thus, a key conclusion of the cannabis use literature is that there is not overwhelming evidence that RCL is associated with increasing rates of cannabis among adolescents, which is notable as potential increases in adolescent use is a concern often voiced by critics of RCL. 16 This might suggest that current RCL policies that limit access to minors may be effective. However, a methodological explanation for the discrepancy between findings for adolescents and adults is that adults may be more willing to report their use of cannabis following RCL as it is now legal for them to use. However, for adolescents’ cannabis use remained illicit, which may lead to biased reporting from adolescents. Thus, additional research using methods to overcome limitations of self-reports may be required.

With regard to other substance use, primarily alcohol and cigarettes, there is little evidence that RCL is associated with increased use rates and may even be associated with decreased rates of cigarette use. 42 , 61 The lack of a relationship with RCL and increasing alcohol and other substance use, seen in 60% of studies, is relevant due to concerns of RCL causing “spill-over” effects to substances other than cannabis. However, the decreasing rates on cigarette use associated with RCL seen in 33% of studies may also suggest a substitution effect of cannabis. 105 It is possible that RCL encourages a substitution effect where cannabis is used to replace use other substances such as cigarettes, but 66% of studies found no association of RCL and cigarette use so further research examining a potential substitution effect is needed. In sum, the literature points to a heterogenous impact of RCL on cannabis and other substance use rates, suggesting complex effects of RCL on use rates that may vary across age and population. However, the review also highlights that there are still limited studies examining RCL and other substance use, particularly a lack of multiple studies examining the same age group.

The current evidence for the impact of RCL on attitudes surrounding cannabis revealed mixed or limited results, with 44% studies finding some sort of relationship with attitudes and RCL and 55% studies suggest a lack of or inconsistent relationship. Studies examining cannabis use attitudes or willingness to use revealed conflicting evidence whereas some studies pointed to increased willingness to use associated with RCL, 43 and others found no change or that changes were not specific to regions that implemented RCL. 48 For attitude-related studies that did reveal consistent findings (eg, use motivation changes, perceptions of lower risk and greater benefits of use), the literature was limited in the number of studies or involved heterogenous samples, making it difficult to make conclusive statements surrounding the effect of RCL. As cannabis-related attitudes (eg, perceived risk, intentions to use) can have implications for cannabis use and consequences 106 , 107 it is interesting that current literature does not reveal clear associations of cannabis-related attitudes and RCL. Rather, this review reveals a need for more research examining changes in cannabis-attitudes over time and potential impacts of RCL.

In terms of health outcomes, the empirical literature suggests RCL is associated with increased cannabis-related emergency visits 24 , 67 , 70 , 76 and other health consequences (eg, trauma-related cases 57 ). The literature also suggests there may be other potential negative health consequences associated with RCL, such as increasing adverse birth outcomes and post-mortem cannabis screens. 45 , 89 Synthesizing of the literature points to a well-established relationship of RCL and increasing cannabis-related emergency visits. While some extant literature was mixed, on balance most studies included in the review (70.6%) found consistent evidence of increased emergency service use (eg, emergency department admissions and poison control calls) for both adolescents and adults with only 31% of studies finding mixed or no association with RCL. This points to a need for stricter RCL policies to prevent unintentional consumption or hyperemesis such as promoting safe or lower risk use of cannabis (eg, using lower THC products, avoiding deep inhales while smoking), clearer packaging for cannabis products, and safe storage procedures.

However, the literature on health outcomes outside of emergency service utilization is limited and requires more in-depth evaluations to be fully understood. Additionally, not all health-outcomes indicated negative consequences associated with RCL. There is emerging evidence of the potential of RCL to help decrease CUD and multiple substance hospital admissions 74 , 82 Furthermore, while some findings were mixed and the number of studies limited, 60% of studies found potential for RCL to have protective effects for opioid-related negative consequences. 87 , 88 However, opioid-related findings should be considered in the context of population-level changes in opioid prescriptions and shifting opioid policy influence. 108 Thus, findings may be a result of changes driven by the response to the opioid epidemic rather than RCL, and there remains a need to better disentangle RCL impacts on opioid-related consequences. It is also worth noting that some opioid and cannabis studies are underwritten by the cannabis industry, so the findings should be interpreted with caution due to potential for conflicts of interest. 88 In sum, the overall literature suggests that RCL is associated with both negative and positive health-related consequences and reveals a need to examine the role of RCL across a wide range of health outcomes.

The findings from the driving-related literature do suggest RCL is associated with increased motor vehicle accidents (50% of studies) although the literature was quite evenly split as higher accident rates were not seen across all studies (50% studies). These results point to potential negative consequence associated with RCL and may indicate a need for better measures to prevent driving while under the influence of cannabis in legalized jurisdictions. However, as the evidence was split and predominately in the U.S. additional studies spanning diverse geographical jurisdictions are still needed.

On the other hand, the findings from crime-related outcomes showed some inconsistencies. While one study did suggest minimal decreases for substance-use related arrests in adults, the findings were not consistent across the two studies examining arrest-rates in youth. 100 - 102 These potential decreases in arrest rates for adults can have important implications as cannabis-related crime rates make up a large amount of overall crime statistics and drug-specific arrests. 30 , 31 This discrepancy in youth findings between a U.S. and Canadian study are notable as Canadian RCL policies do include stipulations to allow small scale regulations in youth. Thus, it suggests RCL policies that maintain prohibition of use among underage youth do not address issues related to arrests and crime among youth. In fact, the current literature suggests that cannabis-related charges are still being enforced for youth under the legal age of consumption in the U.S. Another important outcome revealed is racial disparities in cannabis-related arrests. Previous evidence has shown there are racial disparities, particularly between Black, Indigenous, and Hispanic individuals compared to White counterparts, in cannabis-related charges and arrests. 109 , 110 Regarding racial disparities and RCL, there was very little evidence of decreases in disparities for cannabis-related arrests following RCL. 100 , 101 This racialized arresting is significant as it can be associated with additional public health concerns such as physical and mental health outcomes, harm to families involved, and to communities. 111 This finding is particularly concerning as it suggests racialized arrests for cannabis are still occurring despite the intentions of liberalization of cannabis policies to help reduce racial disparities in the criminal justice system. However, it is important to note that there were only 2 studies of racial disparities in cannabis-related arrests and both were conducted in the U.S. Thus, additional research is required before drawing any firm conclusions about the ability of RCL to address systemic issues in the justice system.

Limitations

The findings should be considered within context of the following limitations. The research was predominately from North America (U.S. and Canada). While both countries have either federal or state RCL, findings only from two countries that are geographically connected may not reflect the influence of RCL across different cultures and countries globally. The majority of studies also relied on self-report data for cannabis-related outcomes. Thus, there is a risk that any increases in use or other cannabis-related outcomes may be due to an increased comfort in disclosing cannabis use due to RCL.

Given the large number of studies on multiple outcomes, we chose to focus on implementation of RCL exclusively, rather than related policy changes such as commercialization (ie, the advent of legal sales), to allow for clearer conclusions about the specific impacts on RCL. However, a limitation is that the review does not address the impact of commercialization or changes in product availability. While outside the scope of the current review, it does limit the conclusions that can be drawn about RCL overall as some jurisdictions implemented features of commercialization separately from legalization. For example, in Ontario, Canada, storefronts and edible products became legal a year after initial RCL (when online purchase was the exclusive modality), which may have had an additional impact on behavioral and health-related outcomes. Additionally, the scope of the review was limited to recreational legalization and did not consider other forms of policy changes such as medicinal legalization or decriminalization, as these have been summarized more comprehensively in prior reviews. 112 - 114 Further, this review focused on behavioral and health outcomes; other important outcomes to examine in the future include economic aspects such as cannabis pricing and purchasing behaviors, and product features such as potency. Finally, as this review considered a broad range of outcomes, we did not conduct a meta-analysis which limits conclusions that can be drawn regarding the magnitude of the associations.

Conclusions

The topic of RCL is a contentious and timely issue. With nationwide legalization in multiple countries and liberalizing policies across the U.S., empirical research on the impacts of RCL has dramatically expanded in recent years. This systematic review comprehensively evaluated a variety of outcomes associated with RCL, focusing on longitudinal study designs and revealing a wide variety of findings in terms of substance use, health, cannabis attitudes, crime, and driving outcomes examined thus far. However, the current review highlights that the findings regarding the effects of RCL are highly heterogenous, often inconsistent, and disproportionately focused on certain jurisdictions. With polarizing views surrounding whether RCL is a positive or negative policy change, it is noteworthy that the extant literature does not point to one clear answer at the current time. In general, the collective results do not suggest dramatic changes or negative consequences, but instead suggest that meaningful tectonic shifts are happening for several outcomes that may or may not presage substantive changes in personal and public health risk. Furthermore, it is clear that a more in-depth examinations of negative (eg, frequent use, CUD prevalence, ‘gateway’ relationships with other substance use), or positive consequences (eg, therapeutic benefits for mental health and/or medical conditions, use of safer products and routes of administration), are needed using both quantitative and qualitative approaches.

Acknowledgments

Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding support from the Peter Boris Chair in Addictions Research and a Canada Research Chair in Translational Addiction Research (JM). Funders had no role in the design or execution of the review.

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: James MacKillop discloses he is a principal and senior scientist in Beam Diagnostics, Inc, and a consultant to ClairvoyantRx. No other authors have disclosures.

Author Contributions: The author’s contribution is as follows: study conceptualization and design: KF, JW, JT, JM; data collection and interpretation: KF, EM, MS; manuscript writing and preparation: KF, EM, MS, PN; manuscript reviewing and editing: JW, JT, JM. All authors have reviewed and approved the final manuscript.

• Research article
• Open access
• Published: 04 February 2020

Marijuana legalization and historical trends in marijuana use among US residents aged 12–25: results from the 1979–2016 National Survey on drug use and health

• Xinguang Chen 1 ,
• Xiangfan Chen 2 &
• Hong Yan 2  

BMC Public Health volume  20 , Article number:  156 ( 2020 ) Cite this article

108k Accesses

71 Citations

84 Altmetric

Metrics details

Marijuana is the most commonly used illicit drug in the United States. More and more states legalized medical and recreational marijuana use. Adolescents and emerging adults are at high risk for marijuana use. This ecological study aims to examine historical trends in marijuana use among youth along with marijuana legalization.

Data ( n  = 749,152) were from the 31-wave National Survey on Drug Use and Health (NSDUH), 1979–2016. Current marijuana use, if use marijuana in the past 30 days, was used as outcome variable. Age was measured as the chronological age self-reported by the participants, period was the year when the survey was conducted, and cohort was estimated as period subtracted age. Rate of current marijuana use was decomposed into independent age, period and cohort effects using the hierarchical age-period-cohort (HAPC) model.

After controlling for age, cohort and other covariates, the estimated period effect indicated declines in marijuana use in 1979–1992 and 2001–2006, and increases in 1992–2001 and 2006–2016. The period effect was positively and significantly associated with the proportion of people covered by Medical Marijuana Laws (MML) (correlation coefficients: 0.89 for total sample, 0.81 for males and 0.93 for females, all three p values < 0.01), but was not significantly associated with the Recreational Marijuana Laws (RML). The estimated cohort effect showed a historical decline in marijuana use in those who were born in 1954–1972, a sudden increase in 1972–1984, followed by a decline in 1984–2003.

The model derived trends in marijuana use were coincident with the laws and regulations on marijuana and other drugs in the United States since the 1950s. With more states legalizing marijuana use in the United States, emphasizing responsible use would be essential to protect youth from using marijuana.

Peer Review reports

Introduction

Marijuana use and laws in the united states.

Marijuana is one of the most commonly used drugs in the United States (US) [ 1 ]. In 2015, 8.3% of the US population aged 12 years and older used marijuana in the past month; 16.4% of adolescents aged 12–17 years used in lifetime and 7.0% used in the past month [ 2 ]. The effects of marijuana on a person’s health are mixed. Despite potential benefits (e.g., relieve pain) [ 3 ], using marijuana is associated with a number of adverse effects, particularly among adolescents. Typical adverse effects include impaired short-term memory, cognitive impairment, diminished life satisfaction, and increased risk of using other substances [ 4 ].

Since 1937 when the Marijuana Tax Act was issued, a series of federal laws have been subsequently enacted to regulate marijuana use, including the Boggs Act (1952), Narcotics Control Act (1956), Controlled Substance Act (1970), and Anti-Drug Abuse Act (1986) [ 5 , 6 ]. These laws regulated the sale, possession, use, and cultivation of marijuana [ 6 ]. For example, the Boggs Act increased the punishment of marijuana possession, and the Controlled Substance Act categorized the marijuana into the Schedule I Drugs which have a high potential for abuse, no medical use, and not safe to use without medical supervision [ 5 , 6 ]. These federal laws may have contributed to changes in the historical trend of marijuana use among youth.

Movements to decriminalize and legalize marijuana use

Starting in the late 1960s, marijuana decriminalization became a movement, advocating reformation of federal laws regulating marijuana [ 7 ]. As a result, 11 US states had taken measures to decriminalize marijuana use by reducing the penalty of possession of small amount of marijuana [ 7 ].

The legalization of marijuana started in 1993 when Surgeon General Elder proposed to study marijuana legalization [ 8 ]. California was the first state that passed Medical Marijuana Laws (MML) in 1996 [ 9 ]. After California, more and more states established laws permitting marijuana use for medical and/or recreational purposes. To date, 33 states and the District of Columbia have established MML, including 11 states with recreational marijuana laws (RML) [ 9 ]. Compared with the legalization of marijuana use in the European countries which were more divided that many of them have medical marijuana registered as a treatment option with few having legalized recreational use [ 10 , 11 , 12 , 13 ], the legalization of marijuana in the US were more mixed with 11 states legalized medical and recreational use consecutively, such as California, Nevada, Washington, etc. These state laws may alter people’s attitudes and behaviors, finally may lead to the increased risk of marijuana use, particularly among young people [ 13 ]. Reported studies indicate that state marijuana laws were associated with increases in acceptance of and accessibility to marijuana, declines in perceived harm, and formation of new norms supporting marijuana use [ 14 ].

Marijuana harm to adolescents and young adults

Adolescents and young adults constitute a large proportion of the US population. Data from the US Census Bureau indicate that approximately 60 million of the US population are in the 12–25 years age range [ 15 ]. These people are vulnerable to drugs, including marijuana [ 16 ]. Marijuana is more prevalent among people in this age range than in other ages [ 17 ]. One well-known factor for explaining the marijuana use among people in this age range is the theory of imbalanced cognitive and physical development [ 4 ]. The delayed brain development of youth reduces their capability to cognitively process social, emotional and incentive events against risk behaviors, such as marijuana use [ 18 ]. Understanding the impact of marijuana laws on marijuana use among this population with a historical perspective is of great legal, social and public health significance.

Inconsistent results regarding the impact of marijuana laws on marijuana use

A number of studies have examined the impact of marijuana laws on marijuana use across the world, but reported inconsistent results [ 13 ]. Some studies reported no association between marijuana laws and marijuana use [ 14 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], some reported a protective effect of the laws against marijuana use [ 24 , 26 ], some reported mixed effects [ 27 , 28 ], while some others reported a risk effect that marijuana laws increased marijuana use [ 29 , 30 ]. Despite much information, our review of these reported studies revealed several limitations. First of all, these studies often targeted a short time span, ignoring the long period trend before marijuana legalization. Despite the fact that marijuana laws enact in a specific year, the process of legalization often lasts for several years. Individuals may have already changed their attitudes and behaviors before the year when the law is enacted. Therefore, it may not be valid when comparing marijuana use before and after the year at a single time point when the law is enacted and ignoring the secular historical trend [ 19 , 30 , 31 ]. Second, many studies adapted the difference-in-difference analytical approach designated for analyzing randomized controlled trials. No US state is randomized to legalize the marijuana laws, and no state can be established as controls. Thus, the impact of laws cannot be efficiently detected using this approach. Third, since marijuana legalization is a public process, and the information of marijuana legalization in one state can be easily spread to states without the marijuana laws. The information diffusion cannot be ruled out, reducing the validity of the non-marijuana law states as the controls to compare the between-state differences [ 31 ].

Alternatively, evidence derived based on a historical perspective may provide new information regarding the impact of laws and regulations on marijuana use, including state marijuana laws in the past two decades. Marijuana users may stop using to comply with the laws/regulations, while non-marijuana users may start to use if marijuana is legal. Data from several studies with national data since 1996 demonstrate that attitudes, beliefs, perceptions, and use of marijuana among people in the US were associated with state marijuana laws [ 29 , 32 ].

Age-period-cohort modeling: looking into the past with recent data

To investigate historical trends over a long period, including the time period with no data, we can use the classic age-period-cohort modeling (APC) approach. The APC model can successfully discompose the rate or prevalence of marijuana use into independent age, period and cohort effects [ 33 , 34 ]. Age effect refers to the risk associated with the aging process, including the biological and social accumulation process. Period effect is risk associated with the external environmental events in specific years that exert effect on all age groups, representing the unbiased historical trend of marijuana use which controlling for the influences from age and birth cohort. Cohort effect refers to the risk associated with the specific year of birth. A typical example is that people born in 2011 in Fukushima, Japan may have greater risk of cancer due to the nuclear disaster [ 35 ], so a person aged 80 in 2091 contains the information of cancer risk in 2011 when he/she was born. Similarly, a participant aged 25 in 1979 contains information on the risk of marijuana use 25 years ago in 1954 when that person was born. With this method, we can describe historical trends of marijuana use using information stored by participants in older ages [ 33 ]. The estimated period and cohort effects can be used to present the unbiased historical trend of specific topics, including marijuana use [ 34 , 36 , 37 , 38 ]. Furthermore, the newly established hierarchical APC (HAPC) modeling is capable of analyzing individual-level data to provide more precise measures of historical trends [ 33 ]. The HAPC model has been used in various fields, including social and behavioral science, and public health [ 39 , 40 ].

Several studies have investigated marijuana use with APC modeling method [ 17 , 41 , 42 ]. However, these studies covered only a small portion of the decades with state marijuana legalization [ 17 , 42 ]. For example, the study conducted by Miech and colleagues only covered periods from 1985 to 2009 [ 17 ]. Among these studies, one focused on a longer state marijuana legalization period, but did not provide detailed information regarding the impact of marijuana laws because the survey was every 5 years and researchers used a large 5-year age group which leads to a wide 10-year birth cohort. The averaging of the cohort effects in 10 years could reduce the capability of detecting sensitive changes of marijuana use corresponding to the historical events [ 41 ].

Purpose of the study

In this study, we examined the historical trends in marijuana use among youth using HAPC modeling to obtain the period and cohort effects. These two effects provide unbiased and independent information to characterize historical trends in marijuana use after controlling for age and other covariates. We conceptually linked the model-derived time trends to both federal and state laws/regulations regarding marijuana and other drug use in 1954–2016. The ultimate goal is to provide evidence informing federal and state legislation and public health decision-making to promote responsible marijuana use and to protect young people from marijuana use-related adverse consequences.

Materials and methods

Data sources and study population.

Data were derived from 31 waves of National Survey on Drug Use and Health (NSDUH), 1979–2016. NSDUH is a multi-year cross-sectional survey program sponsored by the Substance Abuse and Mental Health Services Administration. The survey was conducted every 3 years before 1990, and annually thereafter. The aim is to provide data on the use of tobacco, alcohol, illicit drug and mental health among the US population.

Survey participants were noninstitutionalized US civilians 12 years of age and older. Participants were recruited by NSDUH using a multi-stage clustered random sampling method. Several changes were made to the NSDUH after its establishment [ 43 ]. First, the name of the survey was changed from the National Household Survey on Drug Abuse (NHSDA) to NSDUH in 2002. Second, starting in 2002, adolescent participants receive $30 as incentives to improve the response rate. Third, survey mode was changed from personal interviews with self-enumerated answer sheets (before 1999) to the computer-assisted person interviews (CAPI) and audio computer-assisted self-interviews (ACASI) (since 1999). These changes may confound the historical trends [ 43 ], thus we used two dummy variables as covariates, one for the survey mode change in 1999 and another for the survey method change in 2002 to control for potential confounding effect.

Data acquisition

Data were downloaded from the designated website ( https://nsduhweb.rti.org/respweb/homepage.cfm ). A database was used to store and merge the data by year for analysis. Among all participants, data for those aged 12–25 years ( n  = 749,152) were included. We excluded participants aged 26 and older because the public data did not provide information on single or two-year age that was needed for HAPC modeling (details see statistical analysis section). We obtained approval from the Institutional Review Board at the University of Florida to conduct this study.

Variables and measurements

Current marijuana use: the dependent variable. Participants were defined as current marijuana users if they reported marijuana use within the past 30 days. We used the variable harmonization method to create a comparable measure across 31-wave NSDUH data [ 44 ]. Slightly different questions were used in NSDUH. In 1979–1993, participants were asked: “When was the most recent time that you used marijuana or hash?” Starting in 1994, the question was changed to “How long has it been since you last used marijuana or hashish?” To harmonize the marijuana use variable, participants were coded as current marijuana users if their response to the question indicated the last time to use marijuana was within past 30 days.

Chronological age, time period and birth cohort were the predictors. (1) Chronological age in years was measured with participants’ age at the survey. APC modeling requires the same age measure for all participants [ 33 ]. Since no data by single-year age were available for participants older than 21, we grouped all participants into two-year age groups. A total of 7 age groups, 12–13, ..., 24–25 were used. (2) Time period was measured with the year when the survey was conducted, including 1979, 1982, 1985, 1988, 1990, 1991... 2016. (3). Birth cohort was the year of birth, and it was measured by subtracting age from the survey year.

The proportion of people covered by MML: This variable was created by dividing the population in all states with MML over the total US population. The proportion was computed by year from 1996 when California first passed the MML to 2016 when a total of 29 states legalized medical marijuana use. The estimated proportion ranged from 12% in 1996 to 61% in 2016. The proportion of people covered by RML: This variable was derived by dividing the population in all states with RML with the total US population. The estimated proportion ranged from 4% in 2012 to 21% in 2016. These two variables were used to quantitatively assess the relationships between marijuana laws and changes in the risk of marijuana use.

Covariates: Demographic variables gender (male/female) and race/ethnicity (White, Black, Hispanic and others) were used to describe the study sample.

Statistical analysis

We estimated the prevalence of current marijuana use by year using the survey estimation method, considering the complex multi-stage cluster random sampling design and unequal probability. A prevalence rate is not a simple indicator, but consisting of the impact of chronological age, time period and birth cohort, named as age, period and cohort effects, respectively. Thus, it is biased if a prevalence rate is directly used to depict the historical trend. HAPC modeling is an epidemiological method capable of decomposing prevalence rate into mutually independent age, period and cohort effects with individual-level data, while the estimated period and cohort effects provide an unbiased measure of historical trend controlling for the effects of age and other covariates. In this study, we analyzed the data using the two-level HAPC cross-classified random-effects model (CCREM) [ 36 ]:

Where M ijk represents the rate of marijuana use for participants in age group i (12–13, 14,15...), period j (1979, 1982,...) and birth cohort k (1954–55, 1956–57...); parameter α i (age effect) was modeled as the fixed effect; and parameters β j (period effect) and γ k (cohort effect) were modeled as random effects; and β m was used to control m covariates, including the two dummy variables assessing changes made to the NSDUH in 1999 and 2002, respectively.

The HAPC modeling analysis was executed using the PROC GLIMMIX. Sample weights were included to obtain results representing the total US population aged 12–25. A ridge-stabilized Newton-Raphson algorithm was used for parameter estimation. Modeling analysis was conducted for the overall sample, stratified by gender. The estimated age effect α i , period β j and cohort γ k (i.e., the log-linear regression coefficients) were directly plotted to visualize the pattern of change.

To gain insight into the relationship between legal events and regulations at the national level, we listed these events/regulations along with the estimated time trends in the risk of marijuana from HAPC modeling. To provide a quantitative measure, we associated the estimated period effect with the proportions of US population living with MML and RML using Pearson correlation. All statistical analyses for this study were conducted using the software SAS, version 9.4 (SAS Institute Inc., Cary, NC).

Sample characteristics

Data for a total of 749,152 participants (12–25 years old) from all 31-wave NSDUH covering a 38-year period were analyzed. Among the total sample (Table  1 ), 48.96% were male and 58.78% were White, 14.84% Black, and 18.40% Hispanic.

Prevalence rate of current marijuana use

As shown in Fig.  1 , the estimated prevalence rates of current marijuana use from 1979 to 2016 show a “V” shaped pattern. The rate was 27.57% in 1979, it declined to 8.02% in 1992, followed by a gradual increase to 14.70% by 2016. The pattern was the same for both male and female with males more likely to use than females during the whole period.

Prevalence rate (%) of current marijuana use among US residents 12 to 25 years of age during 1979–2016, overall and stratified by gender. Derived from data from the 1979–2016 National Survey on Drug Use and Health (NSDUH)

HAPC modeling and results

Estimated age effects α i from the CCREM [ 1 ] for current marijuana use are presented in Fig.  2 . The risk by age shows a 2-phase pattern –a rapid increase phase from ages 12 to 19, followed by a gradually declining phase. The pattern was persistent for the overall sample and for both male and female subsamples.

Age effect for the risk of current marijuana use, overall and stratified by male and female, estimated with hierarchical age-period-cohort modeling method with 31 waves of NSDUH data during 1979–2016. Age effect α i were log-linear regression coefficients estimated using CCREM (1), see text for more details

The estimated period effects β j from the CCREM [ 1 ] are presented in Fig.  3 . The period effect reflects the risk of current marijuana use due to significant events occurring over the period, particularly federal and state laws and regulations. After controlling for the impacts of age, cohort and other covariates, the estimated period effect indicates that the risk of current marijuana use had two declining trends (1979–1992 and 2001–2006), and two increasing trends (1992–2001 and 2006–2016). Epidemiologically, the time trends characterized by the estimated period effects in Fig. 3 are more valid than the prevalence rates presented in Fig. 1 because the former was adjusted for confounders while the later was not.

Period effect for the risk of marijuana use for US adolescents and young adults, overall and by male/female estimated with hierarchical age-period-cohort modeling method and its correlation with the proportion of US population covered by Medical Marijuana Laws and Recreational Marijuana Laws. Period effect β j were log-linear regression coefficients estimated using CCREM (1), see text for more details

Correlation of the period effect with proportions of the population covered by marijuana laws: The Pearson correlation coefficient of the period effect with the proportions of US population covered by MML during 1996–2016 was 0.89 for the total sample, 0.81 for male and 0.93 for female, respectively ( p  < 0.01 for all). The correlation between period effect and proportion of US population covered by RML was 0.64 for the total sample, 0.59 for male and 0.49 for female ( p  > 0.05 for all).

Likewise, the estimated cohort effects γ k from the CCREM [ 1 ] are presented in Fig.  4 . The cohort effect reflects changes in the risk of current marijuana use over the period indicated by the year of birth of the survey participants after the impacts of age, period and other covariates are adjusted. Results in the figure show three distinctive cohorts with different risk patterns of current marijuana use during 1954–2003: (1) the Historical Declining Cohort (HDC): those born in 1954–1972, and characterized by a gradual and linear declining trend with some fluctuations; (2) the Sudden Increase Cohort (SIC): those born from 1972 to 1984, characterized with a rapid almost linear increasing trend; and (3) the Contemporary Declining Cohort (CDC): those born during 1984 and 2003, and characterized with a progressive declining over time. The detailed results of HAPC modeling analysis were also shown in Additional file 1 : Table S1.

Cohort effect for the risk of marijuana use among US adolescents and young adults born during 1954–2003, overall and by male/female, estimated with hierarchical age-period-cohort modeling method. Cohort effect γ k were log-linear regression coefficients estimated using CCREM (1), see text for more details

This study provides new data regarding the risk of marijuana use in youth in the US during 1954–2016. This is a period in the US history with substantial increases and declines in drug use, including marijuana; accompanied with many ups and downs in legal actions against drug use since the 1970s and progressive marijuana legalization at the state level from the later 1990s till today (see Additional file 1 : Table S2). Findings of the study indicate four-phase period effect and three-phase cohort effect, corresponding to various historical events of marijuana laws, regulations and social movements.

Coincident relationship between the period effect and legal drug control

The period effect derived from the HAPC model provides a net effect of the impact of time on marijuana use after the impact of age and birth cohort were adjusted. Findings in this study indicate that there was a progressive decline in the period effect during 1979 and 1992. This trend was corresponding to a period with the strongest legal actions at the national level, the War on Drugs by President Nixon (1969–1974) President Reagan (1981–1989) [ 45 ], and President Bush (1989) [ 45 ],and the Anti-Drug Abuse Act (1986) [ 5 ].

The estimated period effect shows an increasing trend in 1992–2001. During this period, President Clinton advocated for the use of treatment to replace incarceration (1992) [ 45 ], Surgeon General Elders proposed to study marijuana legalization (1993–1994) [ 8 ], President Clinton’s position of the need to re-examine the entire policy against people who use drugs, and decriminalization of marijuana (2000) [ 45 ] and the passage of MML in eight US states.

The estimated period effect shows a declining trend in 2001–2006. Important laws/regulations include the Student Drug Testing Program promoted by President Bush, and the broadened the public schools’ authority to test illegal drugs among students given by the US Supreme Court (2002) [ 46 ].

The estimated period effect increases in 2006–2016. This is the period when the proportion of the population covered by MML progressively increased. This relation was further proved by a positive correlation between the estimated period effect and the proportion of the population covered by MML. In addition, several other events occurred. For example, over 500 economists wrote an open letter to President Bush, Congress and Governors of the US and called for marijuana legalization (2005) [ 47 ], and President Obama ended the federal interference with the state MML, treated marijuana as public health issues, and avoided using the term of “War on Drugs” [ 45 ]. The study also indicates that the proportion of population covered by RML was positively associated with the period effect although not significant which may be due to the limited number of data points of RML. Future studies may follow up to investigate the relationship between RML and rate of marijuana use.

Coincident relationship between the cohort effect and legal drug control

Cohort effect is the risk of marijuana use associated with the specific year of birth. People born in different years are exposed to different laws, regulations in the past, therefore, the risk of marijuana use for people may differ when they enter adolescence and adulthood. Findings in this study indicate three distinctive cohorts: HDC (1954–1972), SIC (1972–1984) and CDC (1984–2003). During HDC, the overall level of marijuana use was declining. Various laws/regulations of drug use in general and marijuana in particular may explain the declining trend. First, multiple laws passed to regulate the marijuana and other substance use before and during this period remained in effect, for example, the Marijuana Tax Act (1937), the Boggs Act (1952), the Narcotics Control Act (1956) and the Controlled Substance Act (1970). Secondly, the formation of government departments focusing on drug use prevention and control may contribute to the cohort effect, such as the Bureau of Narcotics and Dangerous Drugs (1968) [ 48 ]. People born during this period may be exposed to the macro environment with laws and regulations against marijuana, thus, they may be less likely to use marijuana.

Compared to people born before 1972, the cohort effect for participants born during 1972 and 1984 was in coincidence with the increased risk of using marijuana shown as SIC. This trend was accompanied by the state and federal movements for marijuana use, which may alter the social environment and public attitudes and beliefs from prohibitive to acceptive. For example, seven states passed laws to decriminalize the marijuana use and reduced the penalty for personal possession of small amount of marijuana in 1976 [ 7 ]. Four more states joined the movement in two subsequent years [ 7 ]. People born during this period may have experienced tolerated environment of marijuana, and they may become more acceptable of marijuana use, increasing their likelihood of using marijuana.

A declining cohort CDC appeared immediately after 1984 and extended to 2003. This declining cohort effect was corresponding to a number of laws, regulations and movements prohibiting drug use. Typical examples included the War on Drugs initiated by President Nixon (1980s), the expansion of the drug war by President Reagan (1980s), the highly-publicized anti-drug campaign “Just Say No” by First Lady Nancy Reagan (early 1980s) [ 45 ], and the Zero Tolerance Policies in mid-to-late 1980s [ 45 ], the Anti-Drug Abuse Act (1986) [ 5 ], the nationally televised speech of War on Drugs declared by President Bush in 1989 and the escalated War on Drugs by President Clinton (1993–2001) [ 45 ]. Meanwhile many activities of the federal government and social groups may also influence the social environment of using marijuana. For example, the Federal government opposed to legalize the cultivation of industrial hemp, and Federal agents shut down marijuana sales club in San Francisco in 1998 [ 48 ]. Individuals born in these years grew up in an environment against marijuana use which may decrease their likelihood of using marijuana when they enter adolescence and young adulthood.

This study applied the age-period-cohort model to investigate the independent age, period and cohort effects, and indicated that the model derived trends in marijuana use among adolescents and young adults were coincident with the laws and regulations on marijuana use in the United States since the 1950s. With more states legalizing marijuana use in the United States, emphasizing responsible use would be essential to protect youth from using marijuana.

Limitations

This study has limitations. First, study data were collected through a household survey, which is subject to underreporting. Second, no causal relationship can be warranted using cross-sectional data, and further studies are needed to verify the association between the specific laws/regulation and the risk of marijuana use. Third, data were available to measure single-year age up to age 21 and two-year age group up to 25, preventing researchers from examining the risk of marijuana use for participants in other ages. Lastly, data derived from NSDUH were nation-wide, and future studies are needed to analyze state-level data and investigate the between-state differences. Although a systematic review of all laws and regulations related to marijuana and other drugs is beyond the scope of this study, findings from our study provide new data from a historical perspective much needed for the current trend in marijuana legalization across the nation to get the benefit from marijuana while to protect vulnerable children and youth in the US. It provides an opportunity for stack-holders to make public decisions by reviewing the findings of this analysis together with the laws and regulations at the federal and state levels over a long period since the 1950s.

Availability of data and materials

The data of the study are available from the designated repository ( https://nsduhweb.rti.org/respweb/homepage.cfm ).

Abbreviations

Audio computer-assisted self-interviews

Age-period-cohort modeling

Computer-assisted person interviews

Cross-classified random-effects model

Contemporary Declining Cohort

Hierarchical age-period-cohort

Historical Declining Cohort

Medical Marijuana Laws

National Household Survey on Drug Abuse

National Survey on Drug Use and Health

Recreational Marijuana Laws

Sudden Increase Cohort

The United States

CDC. Marijuana and Public Health. 2017. Available from: https://www.cdc.gov/marijuana/index.htm . Accessed 13 June 2018.

SAMHSA. Results from the 2015 National Survey on Drug Use and Health: Detailed Tables. 2016 [cited 2018 Jan 31]. Available from: https://www.samhsa.gov/data/sites/default/files/NSDUH-DetTabs-2015/NSDUH-DetTabs-2015/NSDUH-DetTabs-2015.htm

Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda, Board on Population Health and Public Health Practice, Health and Medicine Division, National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, D.C.: National Academies Press; 2017.

Collins C. Adverse health effects of marijuana use. N Engl J Med. 2014;371(9):879.

PubMed   Google Scholar  

Belenko SR. Drugs and drug policy in America: a documentary history. Westport: Greenwood Press; 2000.

Google Scholar  

Gerber RJ. Legalizing marijuana: Drug policy reform and prohibition politics. Westport: Praeger; 2004.

Single EW. The impact of marijuana decriminalization: an update. J Public Health Policy. 1989:456–66.

Article   CAS   Google Scholar  

SFChronicle. Ex-surgeon general backed legalizing marijuana before it was cool [Internet]. 2016 [cited 2018 Oct 7]. Available from: https://www.sfchronicle.com/business/article/Ex-surgeon-general-backed-legalizing-marijuana-6799348.php

PROCON. 31 Legal Medical Marijuana States and DC. 2018 [cited 2018 Oct 4]. Available from: https://medicalmarijuana.procon.org/view.resource.php?resourceID=000881

Bifulco M, Pisanti S. Medicinal use of cannabis in Europe: the fact that more countries legalize the medicinal use of cannabis should not become an argument for unfettered and uncontrolled use. EMBO Rep. 2015;16(2):130–2.

European Monitoring Centre for Drugs and Drug Addiction. Models for the legal supply of cannabis: recent developments (Perspectives on drugs). 2016. Available from: http://www.emcdda.europa.eu/publications/pods/legal-supply-of-cannabis . Accessed 10 Jan 2020.

European Monitoring Centre for Drugs and Drug Addiction. Cannabis policy: status and recent developments. 2017. Available from: http://www.emcdda.europa.eu/topics/cannabis-policy_en#section2 . Accessed 10 Jan 2020.

Hughes B, Matias J, Griffiths P. Inconsistencies in the assumptions linking punitive sanctions and use of cannabis and new psychoactive substances in Europe. Addiction. 2018;113(12):2155–7.

Article   Google Scholar  

Anderson DM, Hansen B, Rees DI. Medical marijuana laws and teen marijuana use. Am Law Econ Rev. 2015;17(2):495-28.

United States Census Bureau. Annual Estimates of the Resident Population by Single Year of Age and Sex for the United States, States, and Puerto Rico Commonwealth: April 1, 2010 to July 1, 2016 2016 Population Estimates. 2017 [cited 2018 Mar 14]. Available from: https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=bkmk

Chen X, Yu B, Lasopa S, Cottler LB. Current patterns of marijuana use initiation by age among US adolescents and emerging adults: implications for intervention. Am J Drug Alcohol Abuse. 2017;43(3):261–70.

Miech R, Koester S. Trends in U.S., past-year marijuana use from 1985 to 2009: an age-period-cohort analysis. Drug Alcohol Depend. 2012;124(3):259–67.

Steinberg L. The influence of neuroscience on US supreme court decisions about adolescents’ criminal culpability. Nat Rev Neurosci. 2013;14(7):513–8.

Sarvet AL, Wall MM, Fink DS, Greene E, Le A, Boustead AE, et al. Medical marijuana laws and adolescent marijuana use in the United States: a systematic review and meta-analysis. Addiction. 2018;113(6):1003–16.

Hasin DS, Wall M, Keyes KM, Cerdá M, Schulenberg J, O’Malley PM, et al. Medical marijuana laws and adolescent marijuana use in the USA from 1991 to 2014: results from annual, repeated cross-sectional surveys. Lancet Psychiatry. 2015;2(7):601–8.

Pacula RL, Chriqui JF, King J. Marijuana decriminalization: what does it mean in the United States? National Bureau of Economic Research; 2003.

Donnelly N, Hall W, Christie P. The effects of the Cannabis expiation notice system on the prevalence of cannabis use in South Australia: evidence from the National Drug Strategy Household Surveys 1985-95. Drug Alcohol Rev. 2000;19(3):265–9.

Gorman DM, Huber JC. Do medical cannabis laws encourage cannabis use? Int J Drug Policy. 2007;18(3):160–7.

Lynne-Landsman SD, Livingston MD, Wagenaar AC. Effects of state medical marijuana laws on adolescent marijuana use. Am J Public Health. 2013 Aug;103(8):1500–6.

Pacula RL, Powell D, Heaton P, Sevigny EL. Assessing the effects of medical marijuana laws on marijuana and alcohol use: the devil is in the details. National Bureau of Economic Research; 2013.

Harper S, Strumpf EC, Kaufman JS. Do medical marijuana laws increase marijuana use? Replication study and extension. Ann Epidemiol. 2012;22(3):207–12.

Stolzenberg L, D’Alessio SJ, Dariano D. The effect of medical cannabis laws on juvenile cannabis use. Int J Drug Policy. 2016;27:82–8.

Wang GS, Roosevelt G, Heard K. Pediatric marijuana exposures in a medical marijuana state. JAMA Pediatr. 2013;167(7):630–3.

Wall MM, Poh E, Cerdá M, Keyes KM, Galea S, Hasin DS. Adolescent marijuana use from 2002 to 2008: higher in states with medical marijuana laws, cause still unclear. Ann Epidemiol. 2011;21(9):714–6.

Chen X, Yu B, Stanton B, Cook RL, Chen D-GD, Okafor C. Medical marijuana laws and marijuana use among U.S. adolescents: evidence from michigan youth risk behavior surveillance data. J Drug Educ. 2018;47237918803361.

Chen X. Information diffusion in the evaluation of medical marijuana laws’ impact on risk perception and use. Am J Public Health. 2016;106(12):e8.

Chen X, Yu B, Stanton B, Cook RL, Chen DG, Okafor C. Medical marijuana laws and marijuana use among US adolescents: Evidence from Michigan youth risk behavior surveillance data. J Drug Educ. 2018;48(1-2):18-35.

Yang Y, Land K. Age-Period-Cohort Analysis: New Models, Methods, and Empirical Applications. Boca Raton: Chapman and Hall/CRC; 2013.

Yu B, Chen X. Age and birth cohort-adjusted rates of suicide mortality among US male and female youths aged 10 to 19 years from 1999 to 2017. JAMA Netw Open. 2019;2(9):e1911383.

Akiba S. Epidemiological studies of Fukushima residents exposed to ionising radiation from the Fukushima Daiichi nuclear power plant prefecture--a preliminary review of current plans. J Radiol Prot. 2012;32(1):1–10.

Yang Y, Land KC. Age-period-cohort analysis of repeated cross-section surveys: fixed or random effects? Sociol Methods Res. 2008;36(3):297–326.

O’Brien R. Age-period-cohort models: approaches and analyses with aggregate data. Boca Raton: Chapman and Hall/CRC; 2014.

Book   Google Scholar  

Chen X, Sun Y, Li Z, Yu B, Gao G, Wang P. Historical trends in suicide risk for the residents of mainland China: APC modeling of the archived national suicide mortality rates during 1987-2012. Soc Psychiatry Psychiatr Epidemiol. 2018;54(1):99–110.

Yang Y. Social inequalities in happiness in the United States, 1972 to 2004: an age-period-cohort analysis. Am Sociol Rev. 2008;73(2):204–26.

Reither EN, Hauser RM, Yang Y. Do birth cohorts matter? Age-period-cohort analyses of the obesity epidemic in the United States. Soc Sci Med. 2009;69(10):1439–48.

Kerr WC, Lui C, Ye Y. Trends and age, period and cohort effects for marijuana use prevalence in the 1984-2015 US National Alcohol Surveys. Addiction. 2018;113(3):473–81.

Johnson RA, Gerstein DR. Age, period, and cohort effects in marijuana and alcohol incidence: United States females and males, 1961-1990. Substance Use Misuse. 2000;35(6–8):925–48.

Substance Abuse and Mental Health Services Administration. Results from the 2013 NSDUH: Summary of National Findings, SAMHSA, CBHSQ. 2014 [cited 2018 Sep 23]. Available from: https://www.samhsa.gov/data/sites/default/files/NSDUHresultsPDFWHTML2013/Web/NSDUHresults2013.htm

Bauer DJ, Hussong AM. Psychometric approaches for developing commensurate measures across independent studies: traditional and new models. Psychol Methods. 2009;14(2):101–25.

Drug Policy Alliance. A Brief History of the Drug War. 2018 [cited 2018 Sep 27]. Available from: http://www.drugpolicy.org/issues/brief-history-drug-war

NIDA. Drug testing in schools. 2017 [cited 2018 Sep 27]. Available from: https://www.drugabuse.gov/related-topics/drug-testing/faq-drug-testing-in-schools

Wikipedia contributors. Legal history of cannabis in the United States. 2015. Available from: https://en.wikipedia.org/w/index.php?title=Legal_history_of_cannabis_in_the_United_States&oldid=674767854 . Accessed 24 Oct 2017.

NORML. Marijuana law reform timeline. 2015. Available from: http://norml.org/shop/item/marijuana-law-reform-timeline . Accessed 24 Oct 2017.

Download references

Acknowledgements

Not applicable.

Author information

Authors and affiliations.

Department of Epidemiology, University of Florida, Gainesville, FL, 32608, USA

Bin Yu & Xinguang Chen

Department of Epidemiology and Health Statistics School of Health Sciences, Wuhan University, Wuhan, 430071, China

Xiangfan Chen & Hong Yan

You can also search for this author in PubMed   Google Scholar

Contributions

BY designed the study, collected the data, conducted the data analysis, drafted and reviewed the manuscript; XGC designed the study and reviewed the manuscript. XFC and HY reviewed the manuscript. All authors read and approved the final version of the manuscript.

Corresponding author

Correspondence to Hong Yan .

Ethics declarations

Ethics approval and consent to participate.

The study was reviewed and approved by the Institutional Review Board at the University of Florida. Data in the study were public available.

Consent for publication

All authors consented for the publication.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Additional file 1: table s1..

Estimated Age, Period, Cohort Effects for the Trend of Marijuana Use in Past Month among Adolescents and Emerging Adults Aged 12 to 25 Years, NSDUH, 1979-2016. Table S2. Laws at the federal and state levels related to marijuana use.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Cite this article.

Yu, B., Chen, X., Chen, X. et al. Marijuana legalization and historical trends in marijuana use among US residents aged 12–25: results from the 1979–2016 National Survey on drug use and health. BMC Public Health 20 , 156 (2020). https://doi.org/10.1186/s12889-020-8253-4

Download citation

Received : 15 June 2019

Accepted : 21 January 2020

Published : 04 February 2020

DOI : https://doi.org/10.1186/s12889-020-8253-4

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Adolescents and young adults
• United States

BMC Public Health

ISSN: 1471-2458

• General enquiries: [email protected]

• Departments
• Program Finder
• Admissions Services
• Course Directory
• Academic Calendar
• Hybrid Campus
• Lecture Series
• Convocation
• Strategy and Development
• Implementation and Impact
• Integrity and Oversight
• In the School
• In the Field
• In Baltimore
• Resources for Practitioners
• Articles & News Releases
• In The News
• Statements & Announcements
• At a Glance
• Student Life
• Strategic Priorities
• Inclusion, Diversity, Anti-Racism, and Equity (IDARE)
• What is Public Health?

The Evidence—and Lack Thereof—About Cannabis

Research is still needed on cannabis’s risks and benefits. 

Lindsay Smith Rogers

Although the use and possession of cannabis is illegal under federal law, medicinal and recreational cannabis use has become increasingly widespread.

Thirty-eight states and Washington, D.C., have legalized medical cannabis, while 23 states and D.C. have legalized recreational use. Cannabis legalization has benefits, such as removing the product from the illegal market so it can be taxed and regulated, but science is still trying to catch up as social norms evolve and different products become available. 

In this Q&A, adapted from the August 25 episode of Public Health On Call , Lindsay Smith Rogers talks with Johannes Thrul, PhD, MS , associate professor of Mental Health , about cannabis as medicine, potential risks involved with its use, and what research is showing about its safety and efficacy. 

Do you think medicinal cannabis paved the way for legalization of recreational use?

The momentum has been clear for a few years now. California was the first to legalize it for medical reasons [in 1996]. Washington and Colorado were the first states to legalize recreational use back in 2012. You see one state after another changing their laws, and over time, you see a change in social norms. It's clear from the national surveys that people are becoming more and more in favor of cannabis legalization. That started with medical use, and has now continued into recreational use.

But there is a murky differentiation between medical and recreational cannabis. I think a lot of people are using cannabis to self-medicate. It's not like a medication you get prescribed for a very narrow symptom or a specific disease. Anyone with a medical cannabis prescription, or who meets the age limit for recreational cannabis, can purchase it. Then what they use it for is really all over the place—maybe because it makes them feel good, or because it helps them deal with certain symptoms, diseases, and disorders.

Does cannabis have viable medicinal uses?

The evidence is mixed at this point. There hasn’t been a lot of funding going into testing cannabis in a rigorous way. There is more evidence for certain indications than for others, like CBD for seizures—one of the first indications that cannabis was approved for. And THC has been used effectively for things like nausea and appetite for people with cancer.

There are other indications where the evidence is a lot more mixed. For example, pain—one of the main reasons that people report for using cannabis. When we talk to patients, they say cannabis improved their quality of life. In the big studies that have been done so far, there are some indications from animal models that cannabis might help [with pain]. When we look at human studies, it's very much a mixed bag. 

And, when we say cannabis, in a way it's a misnomer because cannabis is so many things. We have different cannabinoids and different concentrations of different cannabinoids. The main cannabinoids that are being studied are THC and CBD, but there are dozens of other minor cannabinoids and terpenes in cannabis products, all of varying concentrations. And then you also have a lot of different routes of administration available. You can smoke, vape, take edibles, use tinctures and topicals. When you think about the explosion of all of the different combinations of different products and different routes of administration, it tells you how complicated it gets to study this in a rigorous way. You almost need a randomized trial for every single one of those and then for every single indication.

What do we know about the risks of marijuana use?  

Cannabis use disorder is a legitimate disorder in the DSM. There are, unfortunately, a lot of people who develop a problematic use of cannabis. We know there are risks for mental health consequences. The evidence is probably the strongest that if you have a family history of psychosis or schizophrenia, using cannabis early in adolescence is not the best idea. We know cannabis can trigger psychotic symptoms and potentially longer lasting problems with psychosis and schizophrenia. 

It is hard to study, because you also don't know if people are medicating early negative symptoms of schizophrenia. They wouldn't necessarily have a diagnosis yet, but maybe cannabis helps them to deal with negative symptoms, and then they develop psychosis. There is also some evidence that there could be something going on with the impact of cannabis on the developing brain that could prime you to be at greater risk of using other substances later down the road, or finding the use of other substances more reinforcing. 

What benefits do you see to legalization?

When we look at the public health landscape and the effect of legislation, in this case legalization, one of the big benefits is taking cannabis out of the underground illegal market. Taking cannabis out of that particular space is a great idea. You're taking it out of the illegal market and giving it to legitimate businesses where there is going to be oversight and testing of products, so you know what you're getting. And these products undergo quality control and are labeled. Those labels so far are a bit variable, but at least we're getting there. If you're picking up cannabis at the street corner, you have no idea what's in it. 

And we know that drug laws in general have been used to criminalize communities of color and minorities. Legalizing cannabis [can help] reduce the overpolicing of these populations.

What big questions about cannabis would you most like to see answered?

We know there are certain, most-often-mentioned conditions that people are already using medical cannabis for: pain, insomnia, anxiety, and PTSD. We really need to improve the evidence base for those. I think clinical trials for different cannabis products for those conditions are warranted.

Another question is, now that the states are getting more tax revenue from cannabis sales, what are they doing with that money? If you look at tobacco legislation, for example, certain states have required that those funds get used for research on those particular issues. To me, that would be a very good use of the tax revenue that is now coming in. We know, for example, that there’s a lot more tax revenue now that Maryland has legalized recreational use. Maryland could really step up here and help provide some of that evidence.

Are there studies looking into the risks you mentioned?

Large national studies are done every year or every other year to collect data, so we already have a pretty good sense of the prevalence of cannabis use disorder. Obviously, we'll keep tracking that to see if those numbers increase, for example, in states that are legalizing. But, you wouldn't necessarily expect to see an uptick in cannabis use disorder a month after legalization. The evidence from states that have legalized it has not demonstrated that we might all of a sudden see an increase in psychosis or in cannabis use disorder. This happens slowly over time with a change in social norms and availability, and potentially also with a change in marketing. And, with increasing use of an addictive substance, you will see over time a potential increase in problematic use and then also an increase in use disorder.

If you're interested in seeing if cannabis is right for you, is this something you can talk to your doctor about?

I think your mileage may vary there with how much your doctor is comfortable and knows about it. It's still relatively fringe. That will very much depend on who you talk to. But I think as providers and professionals, everybody needs to learn more about this, because patients are going to ask no matter what.

Lindsay Smith Rogers, MA, is the producer of the Public Health On Call podcast , an editor for Expert Insights , and the director of content strategy for the Johns Hopkins Bloomberg School of Public Health.

Could Medical Marijuana Help Address the Opioid Epidemic?

Policy Is Public Health

Medical Marijuana Laws Linked to Health and Labor Supply Benefits in Older Adults

Related Content

How to Offer Support and Find Strength on a Trauma Anniversary

Mental Health in the Workplace: A Conversation Bridging Research and Practice

Activity, Sleep & Dementia

Rev. Pamula Yerby-Hammack Breaking the Stigma of Mental Health

Inside the Movement to Transform Mental Health in Sierra Leone

Numbers, Facts and Trends Shaping Your World

Read our research on:

Full Topic List

Regions & Countries

• Publications
• Our Methods
• Short Reads
• Tools & Resources

Read Our Research On:

Americans overwhelmingly say marijuana should be legal for medical or recreational use

With a growing number of states authorizing the use of marijuana, the public continues to broadly favor legalization of the drug for medical and recreational purposes. 

An overwhelming share of U.S. adults (88%) say either that marijuana should be legal for medical and recreational use by adults (59%) or that it should be legal for medical use only (30%). Just one-in-ten (10%) say marijuana use should not be legal, according to a Pew Research Center survey conducted Oct. 10-16, 2022. These views are virtually unchanged since April 2021.

The new survey follows President Joe Biden’s decision to pardon people convicted of marijuana possession at the federal level and direct his administration to review how marijuana is classified under federal law. It was fielded before the Nov. 8 midterm elections, when two states legalized the use of marijuana for recreational purposes – joining 19 states and the District of Columbia , which had already done so.

Pew Research Center asked this question to track public views about the legal status of marijuana. For this analysis, we surveyed 5,098 adults from Oct. 10-16, 2022. Everyone who took part in this survey is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way nearly all U.S. adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories. Read more about the ATP’s methodology .

Here are the questions used for this report, along with responses, and its methodology .

Over the long term, there has been a steep rise in public support for marijuana legalization, as measured by a separate Gallup survey question that asks whether the use of marijuana should be made legal – without specifying whether it would be legalized for recreational or medical use. This year, 68% of adults say marijuana should be legal , matching the record-high support for legalization Gallup found in 2021.

There continue to be sizable age and partisan differences in Americans’ views about marijuana. While very small shares of adults of any age are completely opposed to the legalization of the drug, older adults are far less likely than younger ones to favor legalizing it for recreational purposes.

This is particularly the case among those ages 75 and older, just three-in-ten of whom say marijuana should be legal for both medical and recreational use. Larger shares in every other age group – including 53% of those ages 65 to 74 – say the drug should be legal for both medical and recreational use.

Republicans are more wary than Democrats about legalizing marijuana for recreational use: 45% of Republicans and Republican-leaning independents favor legalizing marijuana for both medical and recreational use, while an additional 39% say it should only be legal for medical use. By comparison, 73% of Democrats and Democratic leaners say marijuana should be legal for both medical and recreational use; an additional 21% say it should be legal for medical use only.

Ideological differences are evident within each party. About four-in-ten conservative Republicans (37%) say marijuana should be legal for medical and recreational use, compared with a 60% majority of moderate and liberal Republicans.

Nearly two-thirds of conservative and moderate Democrats (63%) say marijuana should be legal for medical and recreational use. An overwhelming majority of liberal Democrats (84%) say the same.

There also are racial and ethnic differences in views of legalizing marijuana. Roughly two-thirds of Black adults (68%) and six-in-ten White adults say marijuana should be legal for medical and recreational use, compared with smaller shares of Hispanic (49%) and Asian adults (48%).

Related: Clear majorities of Black Americans favor marijuana legalization, easing of criminal penalties

In both parties, views of marijuana legalization vary by age

While Republicans and Democrats differ greatly on whether marijuana should be legal for medial and recreational use, there are also age divides within each party.

A 62% majority of Republicans ages 18 to 29 favor making marijuana legal for medical and recreational use, compared with 52% of those ages 30 to 49. Roughly four-in-ten Republicans ages 50 to 64 (41%) and 65 to 74 (38%) say marijuana should be legal for both purposes, as do 18% of those 75 and older.

Still, wide majorities of Republicans in all age groups favor legalizing marijuana for medical use. Even among Republicans 65 and older, just 17% say marijuana use should not be legal even for medical purposes.

While majorities of Democrats across all age groups support legalizing marijuana for medical and recreational use, older Democrats are less likely to say this. About half of Democrats ages 75 and older (51%) say marijuana should be legal for medical or recreational purposes; larger shares of younger Democrats say the same. Still, only 8% of Democrats 75 and older think marijuana should not be legalized even for medical use – similar to the share of all other Democrats who say this.

Note: Here are the questions used for this report, along with responses, and its methodology .

• Drug Policy
• Medicine & Health

Ted Van Green is a research analyst focusing on U.S. politics and policy at Pew Research Center .

9 facts about Americans and marijuana

Most americans favor legalizing marijuana for medical, recreational use, most americans now live in a legal marijuana state – and most have at least one dispensary in their county, clear majorities of black americans favor marijuana legalization, easing of criminal penalties, concern about drug addiction has declined in u.s., even in areas where fatal overdoses have risen the most, most popular.

1615 L St. NW, Suite 800 Washington, DC 20036 USA (+1) 202-419-4300 | Main (+1) 202-857-8562 | Fax (+1) 202-419-4372 |  Media Inquiries

Research Topics

• Email Newsletters

ABOUT PEW RESEARCH CENTER  Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research. Pew Research Center does not take policy positions. It is a subsidiary of  The Pew Charitable Trusts .

© 2024 Pew Research Center

2018 Theses Doctoral

Essays on Cannabis Legalization

Thomas, Danna Kang

Though the drug remains illegal at the federal level, in recent years states and localities have increasingly liberalized their marijuana laws in order to generate tax revenue and save resources on marijuana law enforcement. Many states have adopted some form of medical marijuana and/or marijuana decriminalization laws, and as of 2017, Washington, Colorado, Maine, California, Oregon, Massachusetts, Nevada, Alaska, and the District of Columbia have all legalized marijuana for recreational use. In 2016 recreational marijuana generated over $1.8 billion in sales. Hence, studying marijuana reforms and the policies and outcomes of early recreational marijuana adopters is an important area of research. However, perhaps due to the fact that legalized recreational cannabis is a recent phenomenon, a scarcity of research exists on the impacts of recreational cannabis legalization and the efficacy and efficiency of cannabis regulation. This dissertation aims to fill this gap, using the Washington recreational marijuana market as the primary setting to study cannabis legalization in the United States. Of first order importance in the regulation of sin goods such as cannabis is quantifying the value of the marginal damages of negative externalities. Hence, Chapter 1 (co-authored with Lin Tian) explores the impact of marijuana dispensary location on neighborhood property values, exploiting plausibly exogenous variation in marijuana retailer location. Policymakers and advocates have long expressed concerns that the positive effects of the legalization--e.g., increases in tax revenue--are well spread spatially, but the negative effects are highly localized through channels such as crime. Hence, we use changes in property values to measure individuals' willingness to pay to avoid localized externalities caused by the arrival of marijuana dispensaries. Our key identification strategy is to compare changes in housing sales around winners and losers in a lottery for recreational marijuana retail licenses. (Due to location restrictions, license applicants were required to provide an address of where they would like to locate.) Hence, we have the locations of both actual entrants and potential entrants, which provides a natural difference-in-differences set-up. Using data from King County, Washington, we find an almost 2.4% decrease in the value of properties within a 0.5 mile radius of an entrant, a $9,400 decline in median property values. The aforementioned retail license lottery was used to distribute licenses due to a license quota. Retail license quotas are often used by states to regulate entry into sin goods markets as quotas can restrict consumption by decreasing access and by reducing competition (and, therefore, increasing markups). However, license quotas also create allocative inefficiency. For example, license quotas are often based on the population of a city or county. Hence, licenses are not necessarily allocated to the areas where they offer the highest marginal benefit. Moreover, as seen in the case of the Washington recreational marijuana market, licenses are often distributed via lottery, meaning that in the absence of an efficiency secondary market for licenses, the license recipients are not necessarily the most efficient potential entrants. This allocative inefficiency is generated by heterogeneity in firms and consumers. Therefore, in Chapter 2, I develop a model of demand and firm pricing in order to investigate firm-level heterogeneity and inefficiency. Demand is differentiated by geography and incorporates consumer demographics. I estimate this demand model using data on firm sales from Washington. Utilizing the estimates and firm pricing model, I back out a non-parametric distribution of firm variable costs. These variable costs differ by product and firm and provide a measure of firm inefficiency. I find that variable costs have lower inventory turnover; hence, randomly choosing entrants in a lottery could be a large contributor to allocative inefficiency. Chapter 3 explores the sources of allocative inefficiency in license distribution in the Washington recreational marijuana market. A difficulty in studying the welfare effects of license quotas is finding credible counterfactuals of unrestricted entry. Therefore, I take a structural approach: I first develop a three stage model that endogenizes firm entry and incorporates the spatial demand and pricing model discussed in Chapter 2. Using the estimates of the demand and pricing model, I estimate firms' fixed costs and use data on locations of those potential entrants that did not win Washington's retail license lottery to simulate counterfactual entry patterns. I find that allowing firms to enter freely at Washington's current marijuana tax rate increases total surplus by 21.5% relative to a baseline simulation of Washington's license quota regime. Geographic misallocation and random allocation of licenses account for 6.6\% and 65.9\% of this difference, respectively. Moreover, as the primary objective of these quotas is to mitigate the negative externalities of marijuana consumption, I study alternative state tax policies that directly control for the marginal damages of marijuana consumption. Free entry with tax rates that keep the quantity of marijuana or THC consumed equal to baseline consumption increases welfare by 6.9% and 11.7%, respectively. I also explore the possibility of heterogeneous marginal damages of consumption across geography, backing out the non-uniform sales tax across geography that is consistent with Washington's license quota policy. Free entry with a non-uniform sales tax increases efficiency by over 7% relative to the baseline simulation of license quotas due to improvements in license allocation.

• Cannabis--Law and legislation
• Marijuana industry
• Drug legalization
• Drugs--Economic aspects

More About This Work

• DOI Copy DOI to clipboard

This website uses cookies.

By clicking the "Accept" button or continuing to browse our site, you agree to first-party and session-only cookies being stored on your device to enhance site navigation and analyze site performance and traffic. For more information on our use of cookies, please see our Privacy Policy .

• Journal of Economic Literature

The Public Health Effects of Legalizing Marijuana

• D. Mark Anderson
• Daniel I. Rees
• Article Information

Additional Materials

• Author Disclosure Statement(s) (158.63 KB)

JEL Classification

• R41 Transportation: Demand, Supply, and Congestion; Travel Time; Safety and Accidents; Transportation Noise

The Effects of Recreational Marijuana Legalization on Employment and Earnings

Despite nearly 70 percent of the American public supporting legalization of recreational marijuana, opponents argue that increased marijuana use may diminish motivation, impede cognitive function, and harm health, each of which could adversely affect adults’ economic wellbeing. This study is the first to explore the impacts of recreational marijuana laws (RMLs) on employment and wages. Difference-in-differences estimates show little evidence that RMLs adversely affect labor market outcomes among most working-age individuals. Rather, our estimates show that RML adoption is associated with an increase in agricultural employment, consistent with the opening of a new licit market. A causal interpretation of our findings is supported by (1) event-study analyses using dynamic difference-in-differences estimates designed to expunge bias due to heterogeneous and dynamic treatment effects, and (2) alternative policy estimates generated using a synthetic control design.

Dr. Sabia acknowledges research support from the Center for Health Economics & Policy Studies (CHEPS) at San Diego State University, which has received grant funding from the Charles Koch Foundation and the Troesh Family Foundation. We thank Evan Kim for excellent research assistance on an earlier version of this paper. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.

Dr. Sabia acknowledges research support from the Center for Health Economics & Policy Studies (CHEPS) at San Diego State University, which includes grants received from the Charles Koch Foundation.

MARC RIS BibTeΧ

Download Citation Data

Mentioned in the News

More from nber.

In addition to working papers , the NBER disseminates affiliates’ latest findings through a range of free periodicals — the NBER Reporter , the NBER Digest , the Bulletin on Retirement and Disability , the Bulletin on Health , and the Bulletin on Entrepreneurship  — as well as online conference reports , video lectures , and interviews .

share this!

May 29, 2024

This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

trusted source

Research examines how recreational marijuana legalization affects a state's college enrollment

New research has revealed up to a 9% increase in college first-year enrollments in US states that have legalized recreational marijuana compared with states without such legalization. The study, which is published in Economic Inquiry , found that the increase was from out-of-state enrollments, with early adopter states and public non-research institutions experiencing the most pronounced increases.

Recreational marijuana legalization did not negatively impact degree completion or graduation rate, and it did not affect college prices, quality, or in‐state enrollment.

The findings suggest that some students perceive recreational marijuana legalization as a positive factor that influences their college choice.

"Future research should focus on how this policy impacts peer dynamics and the selection of academic disciplines, with a special emphasis on differentiating between STEM [Science, Technology, Engineering, and Mathematics] and non-STEM fields," said the study's author Ahmed El Fatmaoui, MBA, a graduate student at the University of Oklahoma.

Provided by Wiley

Explore further

Feedback to editors

Trout in mine-polluted rivers are genetically 'isolated,' new study shows

Novel mobile air monitoring technology yields greater insight into post-disaster pollution levels

2 hours ago

New genomic tools for three modern cotton varieties could guide future breeding efforts

3 hours ago

Accelerated approach leads to discovery of a new catalytic promoter on par with decades of study

Controlling ion transport for a blue energy future: Research highlights the potential of nanopore membranes

Tsunami sands help scientists assess Cascadia earthquake models

4 hours ago

Tracing the evolution of ferns' surprisingly sweet defense strategy

5 hours ago

Novel method for mass production of recombinant proteins uses mono-sodium glutamate

The missing puzzle piece: A striking new snake species from the Arabian Peninsula

Microscopic defects in ice influence how massive glaciers flow, study shows

Relevant physicsforums posts, is "college algebra" really just high school "algebra ii".

May 27, 2024

UK School Physics Exam from 1967

Physics education is 60 years out of date.

May 16, 2024

Plagiarism & ChatGPT: Is Cheating with AI the New Normal?

May 13, 2024

Physics Instructor Minimum Education to Teach Community College

May 11, 2024

Studying "Useful" vs. "Useless" Stuff in School

Apr 30, 2024

More from STEM Educators and Teaching

Related Stories

Recreational marijuana legalization and co-use with alcohol among adolescents

Aug 30, 2021

College applications rose in states that legalized recreational marijuana

Jan 9, 2024

Increase in discipline referrals for substance use in Oregon middle schools after recreational marijuana legalized

Oct 18, 2023

Cannabis legalization and rising sales have not contributed to increase in substance abuse, study finds

Apr 18, 2024

Retail outlets for legal marijuana may be associated with alcohol co-use among high school students: Study

Oct 16, 2023

Recreational marijuana availability in Oregon and use among adolescents

Jan 21, 2020

Recommended for you

First-generation medical students face unique challenges and need more targeted support, say researchers

Investigation reveals varied impact of preschool programs on long-term school success

May 2, 2024

Training of brain processes makes reading more efficient

Researchers find lower grades given to students with surnames that come later in alphabetical order

Apr 17, 2024

Earth, the sun and a bike wheel: Why your high-school textbook was wrong about the shape of Earth's orbit

Apr 8, 2024

Touchibo, a robot that fosters inclusion in education through touch

Apr 5, 2024

Let us know if there is a problem with our content

Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. For general inquiries, please use our contact form . For general feedback, use the public comments section below (please adhere to guidelines ).

Please select the most appropriate category to facilitate processing of your request

Thank you for taking time to provide your feedback to the editors.

Your feedback is important to us. However, we do not guarantee individual replies due to the high volume of messages.

E-mail the story

Your email address is used only to let the recipient know who sent the email. Neither your address nor the recipient's address will be used for any other purpose. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form.

Newsletter sign up

Get weekly and/or daily updates delivered to your inbox. You can unsubscribe at any time and we'll never share your details to third parties.

More information Privacy policy

Donate and enjoy an ad-free experience

We keep our content available to everyone. Consider supporting Science X's mission by getting a premium account.

E-mail newsletter

New study highlights significant increases in cannabis use in United States

Long-term trends parallel changes in policy over 43 years.

A new study by a researcher at Carnegie Mellon University assessed cannabis use in the United States between 1979 and 2022, finding that a growing share of cannabis consumers report daily or near-daily use and that their numbers now exceed those of daily and near-daily alcohol drinkers. The study concludes that long-term trends in cannabis use parallel corresponding changes in policy over the same period. The study appears in Addiction .

"The data come from survey self-reports, but the enormous changes in rates of self-reported cannabis use, particularly of daily or near-daily use, suggest that changes in actual use have been considerable," says Jonathan P. Caulkins, professor of operations research and public policy at Carnegie Mellon's Heinz College, who conducted the study. "It is striking that high-frequency cannabis use is now more commonly reported than is high-frequency drinking."

Although prior research has compared cannabis-related and alcohol-related outcomes before and after state-level policy changes to changes over the same period in states without policy change, this study examined long-term trends for the United States as a whole. Caulkins looked at days of use, not just prevalence, and drew comparisons with alcohol, but did not attempt to identify causal effects.

The study used data from the U.S. National Survey on Drug Use and Health (and its predecessor, the National Household Survey on Drug Abuse), examining more than 1.6 million respondents across 27 surveys from 1979 to 2022. Caulkins contrasted rates of use in four milestone years that reflected significant policy change points: 1979 (when the first data became available and the relatively liberal policies of the 1970s ended), 1992 (the end of 12 years of conservative Reagan-Bush-era policies), 2008 (the year before the U.S. Department of Justice signaled explicit federal non-interference with state-level legalizations), and 2022 (the year for the most recent data available). Among the study's findings:

• Reported cannabis use declined to a low in 1992, with partial increases through 2008 and substantial growth since then, particularly for measures of more intensive use.
• Between 2008 and 2022, the per capita rate of reporting past-year use increased 120%, and days of use reported per capita increased 218% (in absolute terms, the rise was from 2.3 billion to 8.1 billion days per year).
• From 1992 to 2022, the per capita rate of reporting daily or near-daily use rose 15-fold. While the 1992 survey recorded 10 times as many daily or near-daily alcohol users as cannabis users (8.9 million versus 0.9 million), the 2022 survey, for the first time, recorded more daily and near-daily users of cannabis than of alcohol (17.7 million versus 14.7 million).
• While far more people drink than use cannabis, high-frequency drinking is less common. In 2022, the median drinker reported drinking on 4-5 days in the previous month versus using cannabis on 15-16 days in the previous month. In 2022, prior-month cannabis consumers were almost four times as likely to report daily or near-daily use (42% versus 11%) and 7.4 times more likely to report daily use (28% versus 3.8%).

"These trends mirror changes in policy, with declines during periods of greater restriction and growth during periods of policy liberalization," explains Caulkins. He notes that this does not mean that policy drove changes in use; both could have been manifestations of changes in underlying culture and attitudes. "But whichever way causal arrows point, cannabis use now appears to be on a fundamentally different scale than it was before legalization."

Among the study's limitations, Caulkins says that because the study relied on general population surveys, the data are self-reported, lack validation from biological samples, and exclude certain subpopulations that may use at different rates than the rest of the population.

• Controlled Substances
• Health Policy
• Illegal Drugs
• STEM Education
• Educational Policy
• Political Science
• General anxiety disorder
• Psychoactive drug
• Clinical depression
• Circadian rhythm
• Functional training

Story Source:

Materials provided by Carnegie Mellon University . Note: Content may be edited for style and length.

Journal Reference :

• Jonathan P. Caulkins. Changes in self‐reported cannabis use in the United States from 1979 to 2022 . Addiction , 2024; DOI: 10.1111/add.16519

Cite This Page :

Explore More

• Computer Vision, Machine Learning Aid Driving
• Most Distant Known Galaxy
• A New Dinosaur from Zimbabwe
• The Case of the Missing Black Holes
• Adjusting Sunglasses for Your Windows
• Novel Gene-Editing Tool Created
• How Hummingbirds Hover With Such Accuracy
• Complete X and Y Chromosomes of Great Apes
• Moonlets Stuck Together Orbit 'Dinky' Asteroid
• Orchids Aid Seedlings Through Fungal Networks

Trending Topics

Strange & offbeat.

Educate your inbox

Subscribe to Here’s the Deal, our politics newsletter for analysis you won’t find anywhere else.

Thank you. Please check your inbox to confirm.

How marijuana’s reclassification could change U.S. drug policy

Amna Nawaz Amna Nawaz

Azhar Merchant Azhar Merchant

Leave your feedback

• Copy URL https://www.pbs.org/newshour/show/how-marijuanas-reclassification-could-change-u-s-drug-policy

This month, President Biden announced the Justice Department is planning a shift in the federal approach to marijuana, reclassifying it from a Schedule I drug to Schedule III. This would put it in the same category as Tylenol and ketamine. It would classify it as a drug that has the potential for abuse but has medicinal benefits. Amna Nawaz discussed more with Natalie Fertig of Politico.

Read the Full Transcript

Notice: Transcripts are machine and human generated and lightly edited for accuracy. They may contain errors.

Amna Nawaz:

This month, President Biden announced the Department of Justice is planning a historic shift in the federal approach to marijuana, reclassifying it from what's known as a Schedule I drug to Schedule III.

This would make federal treatment of marijuana far less restrictive and consider it less dangerous, putting it in the same category as Tylenol with codeine and ketamine. It would classify it as a drug that has potential for abuse, while still being acknowledged for its medicinal benefits.

The president talked about the decision in a video posted on X.

Joe Biden, President of the United States: Far too many lives have been upended because of failed approach to marijuana. And I'm committed to righting those wrongs. You have my word on it.

Joining us now is Natalie Fertig. She's federal cannabis policy reporter for Politico.

Natalie, thanks for being here.

Natalie Fertig, Federal Cannabis Policy Reporter, Politico:

Thanks for having me.

So this is the next step in a reclassification process that the president began back in 2022, right? So walk us through the timeline here. Where in that process are we now?

Natalie Fertig:

So, we just began a 60-day comment period, where the DOJ said, we have now made our formal decision. We have issued a draft rule that we're going to reschedule cannabis.

So the 60 days started last week, and now this could end five months from now or this could end six or seven years from now, depending on if there's legal challenges in that process.

OK, so still a lot we don't yet know, right?

We should note, we have seen a real sea change when it comes to cannabis legalization in America over the past decade or plus.

If you take a look at the map, some 24 states have legalized marijuana possession for adults. Some 38 states have established medical marijuana programs. So more than half of all Americans now live in states where marijuana is recreational, legal at the state level.

So what does this classification or what would this classification change in a practical way?

There's a lot of things that it would not change, actually. But the main difference that it would have is on the cannabis industry itself in the states where it is legal.

It would change the amount of taxes that they have to pay, meaning there might be more money in the cannabis industry's pocket, which means they could expand in legal states.

And what does that mean? There's some, what, 15,000 cannabis dispensaries in the country right now.

So, potential tax changes? Does it change how they interact with banks or anything else?

It's not clear exactly how the big banks will approach the change in schedule. That's one of those remain to be seen once this — all the dust settles.

But what — it would have an impact on the amount of taxes that they pay.

It's also been reported that dispensaries would have to register with the DEA, like other pharmacies would. Is that true? And how would that change the industry?

So, under Schedule III or under Schedule I, where they currently are, they need to register with the DEA. They do not currently. And so one of the other questions of rescheduling is, will the DEA start to enforce some of the rules that the cannabis industry is currently already breaking, like getting registered with the DEA?

So this is something President Biden mentioned in that video he released too, was the impact on the criminal justice system, in particular, people who have already been convicted of marijuana-related crimes.

What would this change mean for them, either retroactively or people who are currently incarcerated?

One of the biggest criticisms of Biden's rescheduling movement is that it doesn't have a big impact on people who have criminal records, especially at the state level.

The majority of people who have criminal records for cannabis are in the state criminal justice system, not in the federal criminal justice system. Biden did issue some pardons for people with low-level nonviolent marijuana offenses, but that's just a couple thousand people.

We do know the proposal needs to move through the DEA. How are they likely to look at this? Do we know if that proposal is going to move through, and when would we see that kind of approval?

Yes, so what we just saw recently was the DEA and the DOJ coming out and saying we have looked at the review that was sent to us by HHS, and we are recommending a reschedule.

People get to comment on that. There might be some legal challenges to that. And so, when the dust settles, there would need to be some big changes or big challenges for the DEA to change its mind on that. It's likely to be a reschedule. But then that reschedule is also likely to get challenged in the courts, which means in the end this might be up to the court system.

It's so fascinating too when you take a look back and you see the America in which this is all unfolding.

We can now say — there was a study published in the journal "Addiction" last month that showed marijuana use now surpasses daily alcohol consumption in the U.S. for the first time in history. And Americans have very different views when it comes to pot right now.

You look at the latest Gallup numbers from a poll last year, found some 70 percent of adults now support legalization. That is the highest number ever reported in that survey. What does your reporting tell you about the why behind all of this, why President Biden is pushing for these changes now?

Well, a big part of that sea change has come from the youngest generation. Gen Z and millennials, my generation, are much more likely to be consuming cannabis than generations before them.

And they're also much more likely to poll in favor of cannabis. And Biden is heading into a really important election right now. He's not necessarily doing as well among those voters, the younger voters, as he would like to. So there's some hope that, potentially, amongst Democrats, something like this with marijuana could push some of those voters that are skeptical or annoyed or frustrated with the president to turn out to vote in November.

We will see if it does, in fact.

Natalie Fertig, federal cannabis policy reporter for Politico, great to have you here. Thanks so much.

Thanks. Thanks for having me.

Listen to this Segment

Watch the Full Episode

Amna Nawaz serves as co-anchor of PBS NewsHour.

Azhar Merchant is Associate Producer for National Affairs.

Support Provided By: Learn more

More Ways to Watch

• PBS iPhone App
• PBS iPad App

Gonzales V. Raich: a Landmark Case in Federalism and Medical Marijuana

This essay about Gonzales v. Raich explores its significance in American federalism and the debate over medical marijuana. It highlights the Supreme Court’s 2005 decision that upheld federal authority to regulate locally grown marijuana, emphasizing the balance between state autonomy and federal power. The essay also discusses the evolving landscape of marijuana legalization and its implications for federal and state relations.

How it works

In the complex framework of American federalism and the ongoing debate surrounding medical marijuana, Gonzales v. Raich stands as a crucial juncture, a battlefield where constitutional interpretations collide, and a testament to the delicate equilibrium between state autonomy and federal authority.

As the new millennium dawned, medical marijuana gained traction as a potential treatment for various ailments, leading to its legalization in several states. California emerged as a pioneer, passing Proposition 215 in 1996 and spearheading medical cannabis legislation. This set the stage for a legal confrontation that reverberated through Washington, D.

C., and resonated across state capitals.

Angel Raich, a Californian suffering from severe medical conditions, depended on medical marijuana to manage her symptoms. Alongside Diane Monson, another Californian using cannabis for medicinal purposes, Raich contested the federal government’s authority to regulate marijuana under the Controlled Substances Act (CSA). They argued that their local cultivation and personal use of cannabis for medical treatment fell outside federal jurisdiction, as it did not involve interstate commerce.

This dispute reached the Supreme Court in 2004 as Gonzales v. Raich, posing a fundamental question: to what extent does Congress’s power to regulate interstate commerce extend to prohibiting the cultivation and use of marijuana for medicinal purposes within states that have legalized it?

In a 6-3 decision in 2005, Justice John Paul Stevens wrote the majority opinion against Raich and Monson. The Court ruled that Congress’s authority to regulate interstate commerce encompassed the regulation of locally grown and consumed marijuana, even if such activities had no direct impact on interstate commerce. This decision heavily relied on precedents like Wickard v. Filburn (1942), which established that intrastate activities could fall under Congress’s regulatory purview if part of a broader economic scheme.

Justice Stevens emphasized the need for a comprehensive federal regulatory approach to controlled substances, highlighting the potential impact of locally grown marijuana on the national market and federal drug law enforcement. The ruling reaffirmed federal law supremacy in areas where Congress chose to exercise its authority, thereby limiting states’ autonomy in shaping drug policy.

However, dissenting justices, led by Justice Sandra Day O’Connor, expressed concerns about the expansive interpretation of federal power under the Commerce Clause. They argued that allowing Congress to regulate purely local, non-commercial activities like medical marijuana cultivation could undermine federalism and the balance of power between federal and state governments.

Gonzales v. Raich sent ripples through the medical marijuana movement and the broader debate over states’ rights versus federal authority. While reinforcing federal enforcement of drug laws, it drew criticism from medical marijuana advocates and states’ rights proponents, who viewed it as an encroachment on individual freedoms and state sovereignty.

In the years following the Supreme Court’s decision, the landscape of marijuana legalization continued to evolve, with more states defying federal prohibition to legalize medical and recreational cannabis. This dynamic prompted calls for legislative reform at the national level.

In 2009, the Obama administration issued the “Ogden Memo,” directing federal prosecutors to prioritize enforcement against major drug traffickers rather than individuals complying with state medical marijuana laws. This marked a shift in federal enforcement policy, showing some deference to state marijuana laws while maintaining federal prohibition.

Subsequent administrations adopted varying approaches to federal marijuana enforcement, reflecting the ongoing tension between state autonomy and federal authority. The legalization of recreational marijuana in states like Colorado and Washington further complicated the federal government’s stance on cannabis regulation.

In 2018, the passage of the Agriculture Improvement Act, or the Farm Bill, federally legalized hemp production, removing hemp-derived CBD from the list of controlled substances. This legislative milestone signaled increasing acceptance of cannabis-related products and paved the way for further reforms in marijuana policy.

Yet, the legacy of Gonzales v. Raich endures as a poignant reminder of the intricate interplay between federal power and states’ rights in the United States. The case encapsulates the enduring tensions within the American federal system, where conflicting visions of governance and individual liberties continue to shape law and policy. As the debate over marijuana legalization and drug policy reform persists, Gonzales v. Raich remains a pivotal touchstone in the ongoing struggle to reconcile divergent interests within the fabric of American federalism.

Cite this page

Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana. (2024, May 28). Retrieved from https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/

"Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana." PapersOwl.com , 28 May 2024, https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/

PapersOwl.com. (2024). Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana . [Online]. Available at: https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/ [Accessed: 31 May. 2024]

"Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana." PapersOwl.com, May 28, 2024. Accessed May 31, 2024. https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/

"Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana," PapersOwl.com , 28-May-2024. [Online]. Available: https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/. [Accessed: 31-May-2024]

PapersOwl.com. (2024). Gonzales v. Raich: A Landmark Case in Federalism and Medical Marijuana . [Online]. Available at: https://papersowl.com/examples/gonzales-v-raich-a-landmark-case-in-federalism-and-medical-marijuana/ [Accessed: 31-May-2024]

Don't let plagiarism ruin your grade

Hire a writer to get a unique paper crafted to your needs.

Our writers will help you fix any mistakes and get an A+!

Please check your inbox.

You can order an original essay written according to your instructions.

Trusted by over 1 million students worldwide

1. Tell Us Your Requirements

2. Pick your perfect writer

3. Get Your Paper and Pay

Hi! I'm Amy, your personal assistant!

Don't know where to start? Give me your paper requirements and I connect you to an academic expert.

short deadlines

100% Plagiarism-Free

Certified writers

Daily marijuana use is increasing. That's cause for concern.

Millions of people drinking daily was already a problem, and millions more now getting high is another. adults have to be smart about the risks of heavy cannabis use..

A man smokes marijuana in lower Manhattan outside the first legal dispensary for recreational marijuana in New York in December 2022. Daily and near daily marijuana use is now more common than high-frequency drinking.

Ted Shaffrey/AP

This will likely come as no surprise to most people, even if they didn’t see the recent news reports on the research: More people are using marijuana, more frequently than ever.

It’s an entirely predictable outcome of marijuana legalization, now in place in 24 states. Some 17.7 million people use marijuana daily or almost daily, which is more than the 14.7 million people who use alcohol daily or on a near-daily basis, according to an analysis of 2022 results from the National Survey on Drug Use and Health. The survey has been in use since 1979, but these latest results mark the first time that more people reported daily pot use than daily drinking.

Advocates of marijuana legalization are quick to cite its benefits. Recreational cannabis sales bring much-needed tax revenue to cash-hungry state governments; Illinois raked in $417.6 million in cannabis sales tax revenue in 2023. Legalization also is a blow to the war on drugs and its disproportionate impact on impoverished Black and Latino communities. There’s no going back to prohibition, especially now that the Drug Enforcement Administration has proposed removing marijuana from its Schedule 1 classification of far more dangerous drugs, such as heroin and ecstasy.

Even so, there are obvious reasons to be concerned about the growing heavy use of marijuana. “Safer than alcohol” is the conventional wisdom, but that doesn’t mean “without risk.”

Daily marijuana use can increase the risk of developing cannabis-associated psychosis, according to Dr. David A. Gorelick of the University of Maryland School of Medicine. Heavy marijuana use has also been linked to heart problems. In a study published earlier this year in the Journal of the American Heart Association, researchers found that the more often someone smoked pot, the greater their risk of experiencing a heart attack or stroke : Daily users had a 25% higher risk of having a heart attack and a 42% higher risk of experiencing a stroke.

It’s also alarming that just as more people are reporting using pot daily, more people are reporting “driving while high” (which explains why you’re smelling pot smoke wafting from the open windows of drivers while sitting in traffic or waiting at a pedestrian crosswalk).

An eye-opening 12 million people age 16 and over reported driving while under the influence of marijuana in 2018, according to a Centers for Disease Control and Prevention analysis. Those ages 21 to 25 were most likely to report driving under the influence of pot.

Millions of people drinking daily was already a problem. Millions more getting high every day is another. But recreational marijuana is here to stay. Adults have to be smart about the risks of how much, and how often, they use pot.

The Sun-Times welcomes letters to the editor and op-eds. See our guidelines .

• Share full article

Advertisement

Supported by

Cannabis Tops Alcohol as Americans’ Daily Drug of Choice

A new study shows a growing number of people are regularly using cannabis, while frequent alcohol consumption has remained stable.

By Christina Caron

For the first time on record, cannabis has outpaced alcohol as the daily drug of choice for Americans.

In 2022 there were 17.7 million people who reported using cannabis either every day or nearly every day, compared with 14.7 million who reported using alcohol with the same frequency, according to a study, published on Wednesday in the journal Addiction that analyzed data from the U.S. National Survey on Drug Use and Health.

While far more people drink than use cannabis, drinking frequently has become slightly less common than it was around 15 years ago, the study found. But the proportion of people in the U.S. who use cannabis frequently has increased 15-fold in the three decades since 1992, when daily cannabis use hit a low point.

Cannabis legalization has also rapidly accelerated since the ’90s. The drug is now legal for recreational use in 24 states and Washington, D.C. , and for medical use in 38 states and D.C.

The sharp increase in the prevalence of high-frequency cannabis use over the last three decades might partly be attributed to a growing acceptance of the drug, said Jonathan P. Caulkins, a professor of public policy at Heinz College at Carnegie Mellon University. And because the survey data was self-reported, people may now feel more comfortable disclosing how often they use it.

Even so, “I don’t think that for most daily or near-daily users it is a health-promoting activity,” he added. “For some, it’s truly harmful.”

Several experts who were not involved in the research said the study’s findings were concerning. Those in favor of legalizing cannabis have argued that making the drug widely available would draw people away from the harms of alcohol, said Beatriz Carlini, a research associate professor in the psychiatry department of the University of Washington in Seattle.

But the study’s data, which shows only a slight decline in frequent alcohol use, suggests this has not been the case.

“It is disheartening,” she said.

Dr. Carlini and others noted that the concentrations of THC, the psychoactive component in marijuana, have increased dramatically over the years.

In 1995, the concentration of THC in cannabis samples seized by the Drug Enforcement Administration was about 4 percent. By 2021, it was about 15 percent . And now cannabis manufacturers are extracting THC to make oils, edibles, wax, sugar-size crystals and glass-like products called shatter with THC levels that can exceed 95 percent.

In the last decade , research has shown that frequent cannabis use — and particularly the use of high-potency products with levels of THC greater than 10 percent — is a risk factor for the onset of schizophrenia and other psychotic disorders.

“But that isn’t to say that use less frequent — monthly or yearly — is necessarily safe,” said Dr. Michael Murphy, an assistant professor of psychiatry at Harvard Medical School and a psychiatrist at McLean Hospital in Belmont, Mass.

“As we see higher rates of cannabis use in young people, I expect to see higher rates of psychotic disorders,” he said.

The risks of developing psychotic symptoms are higher for those who use cannabis before age 25, people who use it frequently, those with a genetic predisposition (for example, a parent or sibling with a psychotic disorder) or individuals who experienced stressful events like abuse, poverty or neglect during childhood.

In states that have legalized cannabis for recreational use, anyone 21 and over can purchase it.

Those who use cannabis frequently are also at risk of developing cannabis addiction as well as cannabinoid hyperemesis syndrome, a condition that causes recurrent vomiting, the experts said.

This latest study arrives on the heels of the Biden administration’s move last week to downgrade marijuana from the most restrictive category of drugs, known as Schedule I, to Schedule III, which includes drugs thought to have a low-to-moderate risk of abuse.

The survey did not collect information about the concentrations of THC in the products purchased by frequent users or note how often the respondents used cannabis each day.

“A lot of people go home and have a vape after work or take a gummy to go to sleep at night,” said Aaron Smith, the co-founder and chief executive of the National Cannabis Industry Association. He didn’t see that kind of casual daily use as a problem, he added.

At the same time, there may be young people who are using throughout the day “and are exposing themselves to a lot more THC than those people who are just taking a puff a day,” said Ziva D. Cooper, the director of the Center for Cannabis and Cannabinoids at the University of California, Los Angeles. “The mental health and the physical health outcomes are probably going to vary drastically when you look at those different groups of people.”

Christina Caron is a Times reporter covering mental health. More about Christina Caron

Recreational marijuana amendment vote coming in 2024. When will weed be legal in Florida?

Floridians are now less than six months away from finding out whether they puff, puff, and pass freely someday.

After facing some challenges in Florida's Supreme Court , voters will have a chance to vote for or against recreational marijuana legalization this November during the general election, otherwise known as Amendment 3 .

In the meantime, Smart & Safe Florida, the organization that’s backing the amendment , has already released four ads advocating for it.

“Vote yes on Amendment 3 and give Floridians access to regulated, safe marijuana,”  one of the ads says . “Giving responsible adults the freedom to make their own choices in their own homes, all while generating billions for better schools and safer communities.”

Here's when you can vote for the amendment and what happens if it does pass.

What is marijuana?

Marijuana is a greenish-gray mixture of the dried flowers from the Cannabis sativa or Cannabis indica plant, according to the  National Institute of Drug Use.

The main psychoactive chemical in marijuana, responsible for most of the intoxicating effects that people seek, is delta-9-tetrahydrocannabinol, or THC. The chemical is found in resin produced by the leaves and buds primarily of the female cannabis plant.

The plant also contains more than 500 other chemicals, including more than 100 compounds that are chemically related to THC, called cannabinoids.

Is weed legal in Florida?

Yes, but only in certain cases.

Marijuana is currently only legal in Florida for those who have a  Medical Marijuana ID Card , which is given to those who have been diagnosed by a doctor with a qualifying condition and can afford it. The amendment for medical marijuana was  adopted by Florida voters  in 2016 by a vote of 71% to 29%.

Is weed legal in Florida? In some cases, yes. Here’s what to know

Getting  a medical marijuana card in Florida  is a three-step process involving a diagnosis from a qualified physician for certain medical conditions, registering in Florida’s Medical Marijuana Use Registry and applying for a registry ID.

Medical marijuana cards cost $75 and must be renewed every year within 45 days of the card's expiration for an additional $75 in addition to the potential cost of visiting a physician.

Possession of marijuana under Florida law is still a crime for those without a card. Anyone with 20 grams or less of weed faces up to a year in jail and up to $1,000 in fines.

Will recreational marijuana be legalized?

Florida voters will see recreational marijuana on the ballot in Florida as an  initiated constitutional amendment , known as Amendment 3, on Tuesday, Nov. 5, the same day as the presidential election.

Amendment 3  seeks to legalize recreational marijuana, allowing those 21 and older to have up to 3 ounces and up to 5 grams of cannabis concentrate.

Smart & Safe Florida has raised to date nearly $55 million , according to a report by the USA TODAY Network's Tallahassee Democrat. Most of that amount has already been spent on gathering enough signatures for the measure to make the ballot and most of that has come from Trulieve, the state's largest medical marijuana operator.

It still needs to receive a supermajority or 60% of the vote. Early voting for the 2024 general election begins Monday, Oct. 21.

What is Florida Amendment 3? What to know about recreational marijuana in Florida

How soon could recreational marijuana become legal if Amendment 3 passes?

Even if the amendment wins at the polls in November, marijuana won't instantly become legal in Florida.

The process of enacting a successful referendum into law can take several months. Even if it does pass, the state legislature has to decide on how to implement the law, including specific regulations around how much marijuana could be purchased at one time, potency limits, rules around marketing, and any other concerns that arise during the process.

Additionally, there could be legal challenges designed to interrupt its codification and tie up implementation in the courts.

Contributing: Tyler Vazquez , FLORIDA TODAY