Marijuana Regulation and Teen Use Rates


Following the enactment of both medical cannabis access laws and adult use marijuana laws, there has not been any significant rise in self-reported marijuana use by adolescents.

  • “The overall percentage of students who reported using marijuana at least 1 time during the previous 30 days in 2019 was not measurably different from the percentage in 2009 (21 percent)…. There was no measurable difference between 2009 and 2019 in the percentage of students who reported that illegal drugs were made available to them on school property.”
  • “This natural-experimental study used state Youth Risk Behavior Survey (YRBS) data collected from participants in grades 9-12 from 1991 to 2015 in 46 states (N = 1,091,723). Taking advantage of heterogeneity across states in MML [medical marijuana law] status and MML dispensary design, difference-in-difference estimates compared states with enacted MMLs/dispensaries to non-MML/dispensaries states. … This study found no evidence between 1991 and 2015 of increases in adolescents reporting past 30-day marijuana use or heavy marijuana use associated with state MML enactment or operational MML dispensaries.”
  • “Canada legalized recreational cannabis use for adults on October 17, 2018 with decision-makers emphasising the need to reduce cannabis use among youth. We sought to characterize trends of youth cannabis use before and after cannabis legalization by relying on a quasi-experimental design evaluating cannabis use among high school students in Alberta, British Columbia, Ontario, and Québec who participated in the COMPASS prospective cohort study. Overall trends in use were examined using a large repeat cross-sectional sample (n=102,685) at two time points before legalization (16/17 and 17/18 school years) and one after (18/19 school year). … In the longitudinal sample, no significant differences in trends of cannabis use over time were found between cohorts for any of the three use frequency metrics. Therefore, it appears that cannabis legalization has not yet been followed by pronounced changes on youth cannabis use.”
  • “The study was a secondary analysis of a longitudinal study of tobacco use among non-daily cigarette smokers. Participants were 563 young adults (aged 18–24) [in California] enrolled in 2015–16 and followed quarterly for 3 years. … Contrary to our expectations, frequency of marijuana use did not change significantly after legalization, and was stable throughout three years of observation. … In examining marijuana use before and after legalization of recreational sales in California, we found that frequency of use did not change significantly overall, including following legalization.”
  • “Youth Risk Behavior Survey data from 47 states from 1999 to 2017 assessed marijuana, alcohol, cigarette, and e-cigarette use among adolescents (14-18+ years; N = 1,077,938). Associations between RML (recreational marijuana legalization) and adolescent past-month substance use were analyzed using quasi-experimental difference-in-differences zero-inflated negative binomial models. … Controlling for other state substance policies, year and state fixed effects, and adolescent demographic characteristics, models found that RML was not associated with a significant shift in the likelihood of marijuana use. … Results suggest minimal short-term effects of RML on adolescent substance use, with small declines in marijuana use.”
  • “This report provides key insights into substance use behaviors of U.S. high school students during 2009–2019. Encouraging findings include decreasing prevalence of current alcohol use and decreases in the prevalence of lifetime use of marijuana. … Lifetime marijuana use increased during 2009–2013 and then decreased during 2013–2019. … The findings in this report indicate that youth substance use has declined in recent years.”
  • “Among adolescents aged 12 to 17, the percentage who were past year marijuana users decreased from 15.8 percent (or 3.9 million people) in 2002 to 13.2 percent (or 3.3 million people) in 2019.”
  • “Separating out the sum total effect of marijuana legalization from the many other influences on the attitudes and behaviors of adolescents is a difficult task. One way to approach this question with scientific rigor is to follow over time the prevalence of adolescent marijuana use in states that have and have not legalized marijuana use. ,,, Taken as a whole, these studies suggest that marijuana legalization has not had much overall effect on marijuana use by children and adolescents, at least during the past two decades. From 2000 to 2019, marijuana legalization changed substantially, and now medical marijuana is legal in 33 states and recreational marijuana use in 11. Despite these changes, adolescent marijuana prevalence has varied little, with the national percentage of US 12th graders who have ever used marijuana hovering within a narrow window of 42% to 49% during this time period.1 In 2019, it was at 44%, toward the lower end of this range. … In summary, prevalence of marijuana use among adolescents has remained remarkably steady over the past 20 years despite substantial changes in its legality across the United States during this period.”
  • “The percentage of adolescents in 2018 who used marijuana in the past year was lower than the percentages in 2002 to 2004 and in 2009 to 2013, but it was similar to the percentages in 2005 to 2008 and in 2014 to 2017.”
  • “Rates of marijuana use by teens have been of great interest to researchers over the past decade, given major social and legislative shifts around the drug. … Fortunately, even as teens’ attitudes toward marijuana’s harms continue to relax, they are not showing corresponding increases in marijuana use.”

Perceived availability of marijuana among young people is falling nationwide

Rates of problematic cannabis use by young people has declined for the better part of the past two decades.

The enactment of medical cannabis laws is not associated with any causal upticks in youth marijuana use

The passage of adult use cannabis laws is not associated with any causal upticks in youth marijuana use in those jurisdictions that have enacted them