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

Abstract

Objectives. 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.Methods. 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.Results. California JSI youths did not demonstrate a significant increase in marijuana use after legalization (b = -0.010; P = .950) or implementation (b = -0.046; P = .846). However, in Pennsylvania, rates of marijuana use increased significantly after legalization (b = 0.602; P = .001) but not after implementation (b = 0.174; P = .533).Conclusions. 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.

FIGURE 1—

Logistic Growth Curve Models of Rates of Marijuana Use, by Age: California and Pennsylvania, 2015–2018 Note. Changes in marijuana use over age were significant for both states (linear age: b = 0.072, P < .001; quadratic age: b = −0.001, P = .001). Nonsignificant age-by-state interactions suggest that age-related increases in marijuana use were similar for California and Pennsylvania (linear age: P = .414; quadratic age: P = .757). Means are depicted. Race/ethnicity, socioeconomic status, day of week, and interview time point were included in the analysis as covariates.

FIGURE 2—

Rates of Marijuana Use in California and Pennsylvania: 2015–2018 Note. T1 = before legalization; T2 = after legalization but before implementation; T3 = after implementation. There were no significant increases in rates of marijuana use across any time period in California. There was a significant increase in rates of marijuana use from T1 to T2 in Pennsylvania (P < .01), but no differences were observed between T2 and T3. Linear age, quadratic age, race/ethnicity, socioeconomic status, day of week, and interview time point were included in the analysis as covariates. *P < .01.