Does Legalizing Recreational Cannabis Lead to Higher Traffic-Fatality Rates?

By Joe Elia

Edited by David G. Fairchild, MD, MPH

New research, published in JAMA Internal Medicine, suggests a potential effect of legalizing recreational cannabis use on traffic-fatality rates.

One study examined traffic-fatality rates in Colorado and Washington State over a period encompassing legalization (2014–17). According to federal statistics, there was an increased fatality rate in Colorado of roughly 1.5 deaths per billion vehicular miles traveled (BVMT) per year (or an estimated 75 excess fatalities per year). That increase was relative to a "synthetic control" — i.e., a group of states that had not legalized cannabis but had similar traffic-fatality rates to Colorado during its pre-legalization period.

Washington, however, showed no increase. The study's authors say the difference may owe to factors such as variance in the density of cannabis shops in the two states or the drug's availability in adjoining states.

The second study examined motor vehicle fatality rates in four legalizing states (including Colorado and Washington). Compared with 20 non-legalizing states, the four showed an aggregate increase of 2.1 deaths per BVMT.

Commentators argue for efforts to establish testing methods and levels of impairment for cannabis.