The study found that on average there was an 11 percent decrease in traffic fatalities in states that had active medical marijuana laws. The study theorized that people were using marijuana in place of other drugs, like alcohol, especially in drivers aged 15 to 44, where the biggest decrease was found. There was little difference in fatality rates among drivers over the age of 45, though that age group represents the bulk of medical marijuana users.
The study said other factors may have contributed to the lower rates. This includes improved healthcare systems, stricter laws, and better infrastructure. The Washington Posts reports that previous studies found drivers under the influence of marijuana tend to drive slower, possibly to compensate for the drug's effects. And not all states had reduced rates. Both California and New Mexico initially saw a decrease, but eventually saw a small increase in traffic fatalities.
The study used traffic-fatality data from 1985 to 2014 from the National Highway Traffic Safety Administration. Researchers accounted for factors like a graduated driver's license program and bans on texting or talking while driving. There isn't one definitive factor, but there is a correlation between marijuana laws and reduced traffic fatalities. Either way, we'll remind you to stay off the road if you're under the influence, and watch the video below if you aren't yet convinced.