Stricter State Cannabis Laws Linked to Less Cannabis Use Among College Students

Cross-sectional survey of 902,486 undergraduates (ages 18–24) from 591 four-year institutions in 47 states, 2008–2019. Time-varying state-level Cannabis Policy Scale (17 policies) and Alcohol Policy Scale (29 policies) scored by efficacy and implementation. Outcomes: 30-day cannabis use, frequent use (20+ days), 30-day alcohol use, 2-week binge drinking (5+ drinks), and co-use. Multilevel models accounting for institution and state clustering.

This is one of the largest studies of how cannabis policy affects a high-risk population. College students are in a critical developmental period and have among the highest cannabis use rates of any age group. The finding that policy restrictiveness has measurable effects on use — even after accounting for alcohol policy — provides evidence that state-level cannabis regulations have real behavioral consequences.

This study provides the behavioral evidence that connects to the tax standardization work (RTHC-00247) and the California retail authorization study (RTHC-00248). Together they sketch a picture: state cannabis policies measurably influence who uses cannabis and how much, retail access adds a local dimension, and tax structures provide a specific policy lever. For the college-age population specifically, the co-use finding is important — cannabis policy appears to reduce not just cannabis use but the particularly risky combination of heavy drinking and frequent cannabis use.

Cross-sectional survey design cannot establish that policies caused the use differences. Self-reported substance use likely underestimates actual use. The 2008–2019 period captures the early legalization era; effects may differ as legal markets mature. The Cannabis Policy Scale weights policies by estimated efficacy, which involves subjective judgment. Four-year college students are not representative of all 18–24-year-olds.