As marijuana has well-documented adverse health effects (discussed below), one of the principal questions permeating the legalization debate is whether liberalized marijuana laws will lead to increased prevalence of use. Generally, US states that have legalized medical or recreational marijuana have higher rates of use than those where all forms of marijuana remain illegal (42–44). However, it is difficult to ascertain whether this is attributable to legalization or is associated with regional variation in permissive attitudes or perceived risk with regard to marijuana (43). Indeed, legal-marijuana states generally have higher rates of use even before legalization (42, 43).
