A new study in the Southern Economic Journal, “Marijuana legalization and traffic fatalities revisited“ by Weiwei Chen and Michael T. French, examines the impact of marijuana legalization on traffic fatalities in the United States. The study’s relevance is underscored by the dramatic changes in the legal landscape of marijuana over the past three decades, with increasing societal acceptance for both medical and recreational purposes.
The research employs data on state-level traffic fatalities from 1990 to 2019, covering all 50 states plus the District of Columbia. For the skeptics, they do control for various state-specific traffic laws, including speed limits, graduated driver-licensing laws, seat belt laws, handheld wireless device and texting bans, and driving-under-influence laws, as well as traffic volume, state demographic and economic characteristics.
The results indicate that medical marijuana legalization has a statistically significant effect on traffic fatalities, in that total fatality rates decreased by about 7.5% after legalization becomes effective. Controlling for other effects suggest an almost 4% drop in fatalities due to medical cannabis legalization. Recreational cannabis laws seem not to have any such pos effect, however. The reason for this is unclear but may relate either to the different demographic groups using more cannabis as a result of medical versus recreational cannabis laws passing. Previous studies have found similar results, with medical marijuana legalization decreasing traffic fatalities. This study shows a robust relationship based on updated data.
It thus seems increasingly established that beyond the direct effects of cannabis in helping people with all kinds of physical and mental illnesses, it also is keeping more people safe from traffic accidents. Why is this? As the authors note, “Compared to alcohol, the impairment effect of marijuana on driving is relatively mild. Individuals who are under the influence of marijuana tend to drive slower, avoid overtaking other vehicles, and increase following distances. The opposite is true for drivers who are under the influence of alcohol.” Couple this observation with the fact that previous studies have detected that cannabis and alcohol are substitutes. With better access to cannabis, people drink less alcohol. So as long as high drivers are safer than drunk drivers, we are all better off when more people have the option to get high instead of going for the bottle.