A new Columbia University study published in Lancet Psychiatry shows that teen marijuana use does not increase after the passage of medical marijuana laws. The study, led by Dr. Debra Hasin, looked at past-30-day marijuana use among over one million adolescents over a 24-month period. While rates of use were higher to begin with in medical marijuana states, rates of use did not change after laws went into effect.
This is not the first study to find that medical marijuana laws do not have an impact on teen use - but this study is the most comprehensive and valid, given the large sample size, the long study period and adjusting results for other factors that might contribute to marijuana use, such as gender, age and geographic location. Additionally, the study was funded by the National Institute on Drug Abuse, which has been critical of the impact of medical marijuana laws on teen use.
"Medical marijuana relieves pain and suffering for millions and does not lead to an increase in teen marijuana use," said Amanda Reiman, manager of Marijuana Law and Policy for the Drug Policy Alliance and professor at UC Berkeley. "This should end the 'What About The Kids' argument used by opponents who try prevent access to marijuana for the sick and dying."
Almost half of U.S. states allow access to medical marijuana, and a majority of Americans now support broader legalization. Colorado, Washington, Alaska, Oregon, and Washington, DC decisively passed legalization laws in the 2012 and 2014 elections, and other states such as California are likely to follow in years to come. Each of these laws clearly specifies that legalization applies to adults only, contains built-in safeguards that restrict sales to minors and funds prevention efforts.
The evidence, in fact, has long-shown that marijuana reforms are unlikely to lead to an increase in youth marijuana use. Numerous researchers have previously looked at the extent of teen marijuana use in states where medical marijuana is legal - and their findings (published in the American Journal of Public Health and the Journal of Adolescent Health) generally show no association between changes in marijuana laws and rates of teenage marijuana use. This has also been the case in California, where marijuana use among teens is less prevalent than before medical marijuana was legalized in 1996. There was also no increase in teen marijuana use following the spate of decriminalization laws in the U.S. in the 1970s, as well as in the Netherlands when marijuana was decriminalized.
Advocates for marijuana law reform have also stressed that marijuana use rates should not be considered the primary metric when evaluating the success of our public policies. Rather, the key measures of effectiveness of marijuana policies should be reduction of problematic marijuana use and reduction of problems associated with marijuana prohibition, such as arresting more than 600,000 people every year for simple marijuana possession.