Researchers report increasing evidence is that motor vehicle crash rates rise when states legalize recreational use and retail sales of marijuana, although what effects marijuana by itself has on drivers remains unclear.
Crash rates spiked with the legalization of recreational marijuana use and retail sales in California, Colorado, Nevada, Oregon and Washington, new studies by two insurer backed organizations, the Insurance Institute for Highway Safety (IIHS) and the affiliated Highway Loss Data Institute (HLDI) show.
However, the preliminary results of a separate IIHS study of injured drivers who visited emergency rooms in California, Colorado and Oregon showed that drivers who used marijuana alone were no more likely to be involved in crashes than drivers who hadn’t used the drug. That is consistent with a 2015 study by the National Highway Traffic Safety Administration that found that a positive test for marijuana was not associated with increased risk of being involved in a police-reported crash.
Despite those increases in crash rates, studies of whether marijuana itself makes drivers more likely to crash have been inconsistent. The latest study showed no increased crash risk associated with the drug, except when combined with alcohol.
“Our latest research makes it clear that legalizing marijuana for recreational use does increase overall crash rates,” says IIHS-HLDI President David Harkey. “That’s obviously something policymakers and safety professionals will need to address as more states move to liberalize their laws — even if the way marijuana affects crash risk for individual drivers remains uncertain.”
More than a third of U.S. states have legalized recreational marijuana for adults 21 and older. The hefty tax revenues those states are earning have others exploring similar legislation, and recent polls indicate that 68 percent of American adults favor legalization. Consumption