Laws allowing medical marijuana have little impact on road safety

State laws that allow the use of medical marijuana are not significantly associated with cannabis-involved driving, according to a new study by Georgia State University associate professor of criminal justice and criminology Eric Sevigny.

Neither are those laws that allow for specific supply provisions, including home cultivation and unlicensed or quasi-legal dispensaries, Sevigny said.

The study, published in Accident Analysis and Prevention in June, uses data from the Fatality Analysis Reporting System and examines vehicular accidents that led to a death between 1993 and 2014.

Sevigny found that in only those jurisdictions with state-licensed medical marijuana dispensaries did the odds of marijuana-involved driving increase by a significant 14 percent. In those states, an additional 87-113 drivers per year tested positive for the drug during the study period.

"It could be that when a dispensary is the point-of-sale, people are more likely to consume the product before getting behind the wheel or reaching their next destination," he said.

The study also found a decrease in marijuana-involved fatal driving accidents in states that neighbor dispensary states, which may be a spillover effect driven by stricter enforcement in those jurisdictions.

"More than half of the states have passed medical marijuana laws. Nine states and the District of Columbia have outright legalized adult recreational marijuana use," said Sevigny, whose research at the Andrew Young School of Policy Studies focuses on crime and public policy. With states enacting and amending these laws at such a fast pace, policymakers need reliable evidence of their impact on driving and roadway safety."

Sevigny encourages states and policymakers considering the legalization of medical or recreational marijuana to use this research and employ proactive laws and tactics.

"States considering the legalization of marijuana should consider using strategies such as pre-rollout messaging that communicates the dangers of drugged driving, like the drunk driving campaigns that have been successful," Sevigny said. "In addition, states may want to implement regulations governing dispensary siting and home delivery services that would potentially decrease the number of people driving while under the influence of marijuana."