How does Marijuana legislation affect crime? Medical and recreational laws across 50 states

Novel policies may generate unintended spillovers, particularly when legalizing one activity alters incentives for other forms of crime. Marijuana legalization provides a useful setting to examine such effects, given the staggered adoption of medical and recreational laws across all 50 U.S. states. Using both difference-in-differences and synthetic difference-in-differences approaches, we assess how specification choices shape estimated impacts on property crime. Initial results from both methods suggest that recreational legalization increases property crime; however, once state-specific time trends are incorporated into our preferred synthetic specification, the effect becomes negative and statistically insignificant. Overall, the findings indicate that estimated crime effects are highly sensitive to identification assumptions and do not provide robust evidence of an increase in property crime following legalization, underscoring the importance of careful empirical design in policy evaluation.