As more and more states pass laws legalizing medical marijuana, the waters surrounding the issue are still a bit murky. Debate has persisted over the dangers of driving while high, but a new study shed some light on the matter. Researchers at Columbia University’s Mailman School of Public Health found that states with medical marijuana laws had significantly fewer deaths from car accidents than those without.

The study, published in the American Journal of Public Health Tuesday, examined data in the Fatality Analysis Reporting System from 1985 to 2014. They found that traffic accident deaths were reduced by an average of 11 percent in places that had implemented medical marijuana laws. The data showed that medical marijuana laws were associated with an immediate decline in traffic fatalities in those aged 15 to 24 and 25 to 44.

The researchers suggested that the lower fatality rates could be due to lower levels of alcohol-impaired driving as people in those states turned to weed instead of alcohol.

The vast majority of Americans think that weed is far less dangerous than alcohol when it comes to getting behind the wheel. Only 29 percent said that driving while impaired by marijuana was a serious problem, according to a 2015 Gallup Poll, while 79 percent said the same thing about alcohol.

The new study, however, was conflicting with findings from a 2014 analysis. A report published in the American Journal of Epidemiology that year found that the number of fatal car accidents involving people who were high tripled over the preceding ten-year period. Researchers also found that the amount of car crash victims who were found to have weed in their systems increased from 4.2 percent in 1999 to 12.2 percent in 2010. While alcohol-related traffic deaths stayed at a similar level of about 40 percent each year, driving under the influence of other substances increased from 16 percent in 1996 to 28 percent in 2010. Among all drugs, marijuana was found most often.