We used data from a national, population-based study to examine the relationship between state-level legalization of marijuana, and state- and individual-level population-based rates of marijuana use and marijuana abuse/dependence. We addressed the following questions: (1) did states that legalized medical marijuana by 2004 exhibit higher rates of past-year marijuana use and abuse/dependence in 2004-2005 than states that did not legalize it?; (2) were individuals living in states that legalized medical marijuana at higher risk for marijuana use, abuse and dependence in the past year than individuals who live in states that did not legalize medical marijuana?; and (3) among marijuana users, was residence in a state that legalized medical marijuana associated with increased risk for meeting criteria for marijuana abuse and dependence?
