Alcohol impairs motor activity and cognitive functioning that is critical for effective and safe driving, increasing risk of accident. In fact, approximately 1/3 of all traffic fatalities are alcohol-related. Why do some people drive after drinking despite these risks? Dr. Denis McCarthy discusses the history of impaired driving and policy, theories of impaired driving-related decision making, and pathways to prevention, intervention, and treatment. Dr. McCarthy also discusses cannabis-impaired driving and important distinctions between cannabis and alcohol. Dr. Denis McCarthy is the Middlebush Professor of Psychology at the University of Missouri. Learn more about his work here.