A new study published online in the American Journal of Public Health looked at data from the National Highway Traffic Safety Administration (NHTSA) on traffic fatalities from 1985 to 2014.
After taking into account many factors that can contribute to traffic deaths, researchers at Columbia University’s Mailman School of Public Health found an 11% reduction in traffic fatalities on average in states that have enacted medical marijuana laws — which was 23 states and the District of Columbia when the numbers were examined.
When you dig deeper into the numbers, the biggest drop in fatalities came from drivers aged 15 to 44.
“We found evidence that states with the marijuana laws in place compared with those which did not, reported, on average, lower rates of drivers endorsing driving after having too many drinks,” said Silvia Martins, a doctor and associate professor who was the study’s senior officer. One theory is that younger people are substituting marijuana for alcohol more as time goes on and laws relax.
Of course, correlation does not always equal causation, so we can’t say for sure that medical marijuana laws are responsible for the reduction in fatalities; but what we can say is that medical marijuana laws do not cause traffic fatalities to go up, as is the claim of many of those who support prohibition and lament that roads will be full of “stoned drivers” if laws legalizing marijuana for any reason are approved.
Many things can contribute to the “impairment” of a driver, and since everyone’s tolerance for cannabis is different, their levels of impairment at certain times can vary. And since marijuana users are much more self-aware than those who have been drinking alcohol, they are able to compensate more for any deficiencies a substance might cause in the ability to operate a motor vehicle.