November 2011

IZA DP No. 6112: Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption

published in: Journal of Law and Economics, 2013, 56 (2), 333-369

To date, 16 states have passed medical marijuana laws, yet very little is known about their effects. Using state-level data, we examine the relationship between medical marijuana laws and a variety of outcomes. Legalization of medical marijuana is associated with increased use of marijuana among adults, but not among minors. In addition, legalization is associated with a nearly 9 percent decrease in traffic fatalities, most likely to due to its impact on alcohol consumption. Our estimates provide strong evidence that marijuana and alcohol are substitutes.

Mellow drivers? Study says states with medical-marijuana laws have lower traffic fatality rates.

By Fredrick Kunkle December 20, 2016

States with medical-marijuana laws have fewer traffic fatalities than those without, especially among younger drivers, a new study has found.

You would think crash rates might be higher, supposing that more drivers are, too — especially around midnight, when a run to a 7-Eleven becomes necessary.

But, no. Researchers at Columbia University’s Mailman School of Public Health found an 11 percent reduction in traffic fatalities on average when examining places that have enacted medical-marijuana laws — 23 states and the District of Columbia. The presence of medical-marijuana dispensaries also correlated with fewer traffic fatalities, the study found.

Silvia Martins, a physician and associate professor who was the study’s senior author, theorized that lower traffic fatality rates in states with marijuana laws might be related to lower levels of alcohol-impaired driving as people, especially younger people, substitute weed for booze.