A new study based on insurance statistics finds no evidence of a link between the legalization of marijuana and higher collision and/or fatality rates, according to a new report. 

Specifically, the Canadian Institute of Actuaries (CIA) and the Casualty Actuarial Society (CAS) analyzed the impact of marijuana decriminalization on the vehicular accident experience in both Canada and the United States. The study did not detect any statistically significant impacts of decriminalization on the car accident fatality rate, insurance claim frequency, or average cost per claim, particularly over the long term.

As it concerns Canada, the evaluation showed there were no significant changes to the trend and seasonal variations in that country’s traffic accidents after the change in legal status of marijuana. So, too, the estimated statewide effects of recreational legalization in the U.S. do not show any consistent, significant results that would support a conclusion that decriminalization led to an increase in road accidents or fatalities.

Noteworthy, the authors of the study state that “temporal patterns of human activity such as yearly, weekly and daily cycles,” as well as poor driving conditions that come with inclement weather are far better predictors of vehicle crashes than marijuana decriminalization.

However, previous research in the U.S. tells a different story. The Insurance Institute for Highway Safety (IIHS) and the Highway Loss Data Institute conducted a series of studies since 2014 examining how legalization has affected crash rates and insurance claims in the first states to legalize recreational use.

In June 2021, the IIHS published findings regarding the most recent of these studies, which showed that injury and fatal crash rates in California, Colorado, Nevada, Oregon, and Washington jumped in the months following the relaxation of marijuana laws in each state.

Combined, the impact of legalization and, subsequently, retail sales in the five states resulted in a 6% increase in injury crash rates and a 4% increase in fatal crash rates compared with other Western states where recreational marijuana use was illegal during the study period. Only the increase in injury crash rates was statistically significant.