Triple-I Weblog | Crashes Enhance as Leisure Marijuana Turns into Authorized, Analysis Signifies


Connecticut became the last state to legalize recreational marijuana this week, and more are expected to follow.

The increase in marijuana use that comes with legalization has raised road safety concerns.

Researchers at the Insurance Institute for Highway Safety (IIHS) and the Highway Loss Data Institute (HLDI) have been studying how legalization has impacted accident rates and insurance claims since 2014, and there is evidence that accident rates rise as states use recreational and retailing legalize sales of marijuana.

The latest of these studies, published June 17 by the IIHS, shows that the number of injuries and fatalities in California, Colorado, Nevada, Oregon, and Washington skyrocketed in the months following the relaxation of marijuana laws in each state is. The five states saw their injuries and fatalities increase by 6 percent and fatalities by 4 percent compared to other western states where recreational marijuana was illegal during the study period.

Only the increase in the accident rate for injuries was statistically significant.

“Our latest research shows that legalizing marijuana for recreational use increases overall crash rates,” said IIHS-HLDI President David Harkey. “Obviously this is something that politicians and safety experts have to learn as more and more states liberalize their laws – even if the way in which marijuana affects the risk of accidents for individual drivers remains uncertain.”

The insurance records show a similar increase in claims from collision insurance, which, according to the latest analysis by HLDI, pays for damage to a culpably insured own vehicle. Legalizing retail sales in Colorado, Nevada, Oregon, and Washington was associated with a 4 percent increase in claims frequency from 2012 to 2019 compared to other western states. That’s slightly less than the 6 percent increase in HLDI found in a previous study. , which covered from 2012 to 2018.

While there is evidence that crash rates in the states have increased that legalized marijuana is on the rise, it seems that more study is needed to determine whether marijuana use alone is responsible. Preliminary data suggests that people who consume alcohol and marijuana together are responsible for most of the crashes.

Another factor may be that marijuana users in counties that do not allow retail sales drive to counties that do. The increased suspension travel could lead to more accidents, even if their accident risk per mile driven is no higher than that of other drivers.