Crash rates increase when states legalize recreational marijuana use and retail sales, according to new research.
The new study by the Insurance Institute for Highway Safety (IIHS) and another study by the affiliated Highway Loss Data Institute (HLDI) revealed a spike in crashes in California, Colorado, Nevada, Oregon and Washington.
The five states saw a six percent increase in injury crash rates and a four percent increase in fatal crash rates compared with other Western states where recreational marijuana use was illegal during the study period.
However, despite those increases in crash rates, studies of whether marijuana itself makes drivers more likely to crash have been inconsistent. The latest one from IIHS — which used data collected from injured drivers in three emergency rooms in Denver, Colorado; Portland, Oregon; and Sacramento, California — showed no increased crash risk associated with the drug, except when combined with alcohol.
According to the IIHS, driving simulator tests have shown that drivers who are high on marijuana react more slowly, find it harder to pay attention, have more difficulty maintaining their car’s position in the lane and make more errors when something goes wrong than they do when they’re sober.
However such tests have also shown marijuana-impaired drivers are likely to drive at slower speeds, make fewer attempts to overtake and keep more distance between their vehicle and the one ahead of them.
“Our latest research makes it clear that legalizing marijuana for recreational use does increase overall crash rates,” said 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.”
