Two studies came to opposite conclusions on whether or not rising marijuana use is leading to the increase in car crashes in states that have legalized the drug.
The first study, conducted by the Insurance Institute for Highway Safety (IIHS), analyzed insurance claims for vehicle collisions filed from 2012 to 2016. The IIHS researchers compared claims in states that had recently legalized marijuana (Oregon, Washington and Colorado) with claims in neighboring states that had not. Researchers found that over that time period, collisions claim frequencies in the states that had legalized marijuana were 3 percent higher than would have been anticipated without legalization. Although researchers characterized that number as small, they also claimed it as significant. Matt Moore, senior vice president of the IIHS’s Highway Loss Data Institute, stated that “the combined-state analysis shows that the first three states to legalize recreational marijuana have experienced more crashes.”
On the other hand, a second study published in the American Journal of Public Health (AJPH), found no increase in vehicle crash fatalities in Colorado and Washington after legalization. The authors of that study analyzed federal data on fatal car crashes from 2009 to 2015 and found no significant association between recreational marijuana legalization in Washington and Colorado and subsequent changes in motor vehicle crash fatality rates in the first 3 years after legalization.
One study finds that legalization led to a small but significant increase in crashes. The other study concludes that legalization had no effect on fatal crashes at all. The question is whether or not these two studies contradict one another, and the answer is no. The studies measured slightly different things: IIHS looked at claims for motor vehicle collisions, while the AJPH report focused specifically on fatal crashes. It seems plausible that legalization could lead to a slight increase in minor accidents that don’t prove fatal. Both approaches have their strengths. But in the end, it’s hardly surprising that choosing different comparison states will yield slightly different results on similar measures.
If you need help in a drug related prosecution, you should speak to Frank T. Luciano. He has almost 40 years of experience with cases of this type. In addition, he is a lifetime member of NORML’s (National Organization for the Reform of Marijuana Laws) legal committee and a long-time member of the National Association of Criminal Defense Lawyers.