Comparative Effects of Recreational and Medical Marijuana Laws on Drug Use among Adults and Adolescents

Abstract

Thirty-four states have medical marijuana laws, and 10 states have recreational marijuana laws. Little research compares how these two types of laws affect drug consumption in the general population or in particular age groups. Using a difference-in-differences strategy, we find that recreational laws increase past-year marijuana use by 25 percent among adults and by 10 percent among adolescents. In contrast, medical laws increase adult use by only 5 percent and have a negligible effect on adolescent use. We also find that recreational marijuana dispensaries are an important driver of the increase in marijuana use for adults 26 and older. Our results suggest that medical laws succeed in mitigating recreational (nonmedical) use, that recreational laws produce large increases in marijuana use in the general population, and that underage marijuana use may be an important problem with existing implementations of recreational marijuana laws.