Legal access to alcohol and automobile accidents: Potential interactive effects of alcohol and drug consumption

The combination of drugged and drunk driving is an important policy topic as some states and countries have liberalized prohibitions on substance use to varying degrees. In this study, we analyze the effect of legal access to alcohol on suspected drug impaired accidents. We find that accidents with suspected drug impairment significantly increase when a driver gains legal access to alcohol at age 21. Our findings suggest that even if alcohol and drug consumption are substitutes, as much of the literature suggests, potential interactive effects may offset the reduction in decreased alcohol consumption from drugs.