Youngki Woo, Dale W. Willits, Mary K. Stohr, Craig Hemmens and Staci Hoff


June 30, 2023


The greater availability of cannabis following legalization increases the likelihood that more drivers will drive drugged, rendering the determination of its effect on crashes a matter of vital public policy interest. For criminal justice agencies, this issue takes on increased importance, as drugged driving is a criminal offense. We examine the relative risk of cannabis (Delta-9-Tetrahydrocannabinols [hereafter THC]), alcohol, and the combination of the two, on fatal crashes in Washington state, using data from the Washington Coded Fatal Crash (WA-CFC) Files, which includes appended toxicology results. Findings indicate the presence of alcohol or the combination of alcohol and THC in the blood of a driver involved in a fatal crash is more likely to be associated with risky driving behaviors, fatal injuries, and death compared to THC alone.


Woo, Y., Willits, D. W., Stohr, M. K., Hemmens, C., & Hoff, S. (2023). Relative risk of cannabis, alcohol, and their combination on driver behavior in fatal crashes in Washington State. Journal of crime and criminal behavior, 3(1), 33-59.