Before Oregon voted to legalize marijuana for all uses back in 2014, one of the hottest topics of debate was the potential impact of legal weed on the state’s roads. Opponents to decriminalization claimed that adding another intoxicant to the mix—we’re not sure we agree that marijuana is toxic, but we’ll save that for another day—would drive accident rates up.
Supporters, on the other hand, claimed that “normal” cannabis use—an admittedly subjective term—does not significantly impair drivers, and is certainly safer than even slight alcohol use, a claim supported by years of studies.
Now, nearly two years into legal marijuana sales in Oregon, a pair of studies attempts to detail the real effect of states that legalized weed on road safety. The findings aren’t conclusive, but the broad takeaway can be summed up by two words: not much.
A Tale of Two Studies: A Rise in Overall Accidents, or a Drop in Traffic Deaths?
A study commissioned by the Insurance Institute for Highway Safety found that, compared with their neighbors, states that legalized weed saw a roughly 3% rise in overall vehicle accident insurance claims.
A superficially similar study by the American Journal of Public Health focused instead on traffic deaths; rather than comparing neighboring states, it compared states that legalized weed to those with similar populations and traffic patterns. Though it didn’t research Oregon specifically, this study found
“…no significant association between recreational marijuana legalization in Washington and Colorado and subsequent changes in motor vehicle fatality rates in the first three years after recreational marijuana legalization.”
Apples and Oranges for Cannabis and Driving?
Because the two studies focused on different aspects of unsafe driving, and because they used slightly different baselines for comparison, it’s difficult to draw a direct comparison between them.
Any potential for a rise in traffic accidents—even a relatively small one—is cause for concern. But the findings of the first study, showing a rise in overall accidents, aren’t conclusive. For one thing, they don’t directly connect their results with cannabis use; that relationship is only circumstantial. As the authors of the second study point out:
“[W]e also found no association between recreational marijuana legalization and total crash rates when analyzing available state-reported nonfatal crash statistics.”
For another thing, previous studies have found a reverse correlation, at least when it comes to medical marijuana. As reported last December by Reuters, states that legalized weed for medical use experienced a decrease in traffic deaths, according to a study analyzing data from 1985 to 2014. Perhaps tellingly, the decrease in fatalities was most significant—down 12%—in the 25- to 44-year-old range, a group with a significant percentage of registered medical marijuana users.
Too Early for Conclusions?
We’re still only a few years into this grand experiment, and it’s safe to say that much more remains to be learned about cannabis, public health, and safety. But while it’s a bit early to draw sweeping conclusions, it appears that marijuana is, at the very worst, not doing a great deal to make our roads more dangerous. And there’s a good chance that, in fact, it’s helping lead a decrease in traffic deaths. And whether or not you support marijuana legalization, that’s good news to hear.