Medical Marijuana Laws Don’t Raise or Lower Fatal Car Crashes, Study Finds

Laws permitting medical cannabis did not have a significant effect on the number of marijuana users involved in fatal car crashes over a 22-year period, according to a June 2018 study.

The study, in peer-reviewed journal Accident Analysis and Prevention, published by Elsevier, examined cannabis use in fatal crashes between 1993 and 2014, though its author, Georgia State University associate professor Eric Sevigny, was careful to caution that the study does not determine whether users were high at the time of the crash — but only whether they had consumed cannabis.

“In general we don’t find medical marijuana laws impact fatal crashes for better or worse,” Sevigny said. “Some supply provisions have a small increasing effect, and from a policy perspective we could see that as a negative.”

The study did not examine whether there was a link between recreational cannabis laws and fatal crashes, because there wasn’t enough data available during that time frame.

State laws regarding medical cannabis use had no effect on the number of cannabis users involved in fatal crashes, either in reducing fatal crashes or increasing their likelihood, the study found.

However, state-licensed dispensaries increased the number of fatal crashes by 14 percent. Though the increase was statistically significant, it did not result in a much larger number of drivers with cannabis in their system.

“States with dispensaries, we find there’s a significant positive increase in cannabis-positive drivers,” said Sevigny, an associate professor of criminology at Georgia State University whose research focuses on crime and public policy.

“Even though it’s significant, when you’re dealing with large datasets, the impact is small,” Sevigny said. “Some of the numbers in there, somewhere on the order of 100, we might see 100 additional drivers who test positive for cannabis in a given year who otherwise wouldn’t have in other dispensary systems.”

Though the reason behind the increase isn’t clear, Sevigny speculated that perhaps medical marijuana users have to drive longer distances to buy cannabis. Some states may also leave a lot of discretion up to cities and counties on whether they allow dispensaries, meaning some people may have to drive farther to buy cannabis products.

To reduce the number of possibly impaired drivers state legislators should consider ways to deliver medical cannabis to patients, Sevigny said. Before legalizing anything, policymakers should also use public messaging about impaired driving targeted toward young people akin to drunken driving public service announcements, which have proven to be effective, he added.

“If the state decides to roll out dispensaries, there are a couple considerations. One is to have some pre-roll out prevention planning,” Sevigny said.

The study, made available online in June 2018, will be published in the September 2018 print edition of Accident Analysis and Prevention.

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