Examining the Effect of Cannabis Legalization on Youth Cannabis Use: Evidence on the Importance of Enforcing Retailer Compliance

Studies show that U.S. state cannabis legalization has increased adult cannabis use, but the effects on youth use are mixed. This study considers whether omission of enforcement of the minimum legal sales age (MLSA) might help explain prior mixed findings. We combine biennial survey data for 6th, 8th, 10th, and 12th grade students from the 2010-2023 Washington Healthy Youth Survey with administrative data on premise and compliance checks from the Washington State Liquor and Cannabis Board (WSLCB). Premise checks educate retailers on any potential violations but do not involve penalties or fines. Compliance checks, on the other hand, involve increasing penalties imposed on retailers if they are found to be noncompliant with sales to minors. We use difference-in-differences (DID) methods that are robust to a staggered policy rollout with dynamic and heterogeneous treatment effects and assess impacts of both types of inspections on past month cannabis use. We conduct a series of sensitivity and robustness checks of the impact of both types of inspections based on student’s grade, length of time since inspection, inclusion of alcohol/tobacco retail compliance checks, and alternative measures of cannabis use. Our research suggests that the implementation of regular random compliance checks with stiff penalties on retailers for noncompliance may help reduce the influence of legal markets on youth use. Unobserved heterogeneity within and across states in the enforcement of MLSAs may contribute to mixed findings of the impact of legalization on youth cannabis use.