Measuring the Impact of Marijuana Legalization with the Washington Roadside Survey of Driver Drug and Alcohol Use

Washington has the dubious distinction of being one of the first states in the United States to legalize the use of recreational marijuana. Even though state-level data have shown that marijuana use is already prevalent, especially among young adults, legalizing a psychoactive drug for recreational purposes certainly increases concern among traffic safety advocates that longstanding efforts to combat impaired driving will be undermined. No one, regardless of their position on the marijuana legality issue, wants an increase in the number of serious injuries or deaths caused by impaired driving.

This major societal shift in Washington caused traffic safety advocates to reevaluate their data with respect to drug-impaired driving. The Washington State Healthy Youth Survey, administered to more than 200,000 youth, ages 12 through 18, in more than 1,000 Washington schools statewide, shows that alcohol use by high school seniors decreased by more than 10 percent from 2002 (42.8 percent) through 2012 (36.1 percent), while marijuana use increased during the same time period. In 2012, over 36 percent of Washington high school seniors said they consumed alcohol within the last 30 days, while almost 27 percent said they smoked marijuana within the last 30 days.1 If youth perceive marijuana to not be dangerous, which is one message youth may receive from legalization, they are more likely to participate in underage use. An increase in use can, in turn, cause an increase in drug-impaired driving.