In the first study, published online in the journal Substance Use & Misuse, researchers at Columbia University in New York surveyed the marijuana use habits of a national sampling of 1,310 adolescents between the years 2013 and 2015. Investigators assessed whether respondents from states with liberalized cannabis policies were more likely to acknowledge having consumed cannabis compared to those residing in jurisdictions where the substance remains criminally prohibited.
Authors reported that the study’s findings “failed to show a relationship between adolescents’ use of marijuana and state laws regarding marijuana use.” … [They] suggest that eased sanctions on adult marijuana use are not associated with higher prevalence rates of marijuana use among adolescents.”
In the second study, published in the journal Drug and Alcohol Dependence, a team of investigators from Columbia University, the University of California at Davis, and Boston University examined the relationship between medical cannabis laws and the prevalence of marijuana availability and use by both adolescents and by those age 26 or older. Authors reported no changes over a nine-year period (2004 to 2013) with regard to the past-month prevalence of marijuana use by those ages 12 to 17 or by those between the ages of 18 and 25. Those age 25 and younger also experienced no change in their perception of marijuana’s availability. By contrast, self-reported marijuana use and availability increased among adults age 26 or older over this same time period.
The conclusions are similar to those of numerous separate studies reporting that changes in marijuana’s legal status are not associated with any uptick in teens’ use of the substance, such as those here, here, here, and here.
Abstracts of the two studies, “Is the Legalization of Marijuana Associated With Its Use by Adolescents?” and “State-level medical marijuana laws, marijuana use and perceived availability of marijuana among the general U.S. population,” appear online here and here.