Marijuana Use Among Justice-Involved Youths After California Statewide Legalization, 2015-2018.

To determine the impact of California's recreational marijuana legalization on marijuana use among justice system-involved (JSI) adolescents and young adults, and to distinguish whether any changes resulted from legalization (passing the law) or from implementation of the law. We compared changes in JSI youths' marijuana use in 2 states: California (n = 504), where recreational marijuana use was recently legalized, and Pennsylvania (n = 478), where recreational use is still prohibited. Furthermore, we examined changes in marijuana use across 3 key time periods (October 2015-June 2018): before legalization, after legalization but before implementation, and after implementation. California JSI youths did not demonstrate a significant increase in marijuana use after legalization (b = -0.010;  = .950) or implementation (b = -0.046;  = .846). However, in Pennsylvania, rates of marijuana use increased significantly after legalization (b = 0.602;  = .001) but not after implementation (b = 0.174;  = .533). Although recreational marijuana legalization was not associated with changes in marijuana use among youths in California, we observed increased rates of use in Pennsylvania after legalization in California. Recreational marijuana laws may be indirectly related to youths' marijuana use by supporting more permissive national attitudes toward marijuana.