Medical Marijuana and Motor Vehicle Fatalities: A Synthetic Control Approach to California's Compassionate Use Act

• In Event: Posters I

Abstract

In November, 1996, California voters approved Proposition 215 (Compassionate Use Act), which legalized the use of marijuana for medical purposes. Although the potential collateral consequences of legalization were not the focus of public debate at the time of enactment, recently, researchers have begun to investigate these unanticipated consequences. For example, would easier access to marijuana lead to an increase in driving under the influence? Would this lead to an increase in traffic fatalities? Anderson et al. (2013) tested these hypotheses and made the surprise finding that traffic fatality rates decreased in medical marijuana states. The authors speculate that, unlike alcohol which is consumed in public places, marijuana is consumed at home. Another possibility, however, is that Anderson et al. failed to control plausible threats to internal validity. To investigate this possibility, we devise a time series experiment for California's Compassionate Use Act using the synthetic control group method to control the common threats to internal validity. Our results suggest that motor vehicle fatalities in California indeed dropped after medical marijuana was legalized.

Authors

• Bradley Bartos, University of California, Irvine

• Richard M. McCleary, University of California, Irvine