Recreational cannabis appears to boost crashes; more study needed

As more states legalize recreational use of marijuana, comparative data on traffic accidents pre- and post-legalization is starting to roll in. Research from the Highway Loss Data Institute shows a 6% rise in collision-claim frequency following recreational legalization in Washington, Oregon and Colorado compared to control states where recreational use is prohibited.

A separate study from the Insurance Institute for Highway Safety that used police-reported crash rates (rather than insurance collision claims) echoes those findings. It found that crashes increased an average of 5.2% in Washington, Oregon and Colorado after recreational legalization.

But even as data pointing to an association between collisions and legalized recreational marijuana seems to emerge, precisely interpreting what it means or an appropriate response is difficult. That's because there's no breathalyzer equivalent for marijuana that can be used at a crash scene, and current THC detection tests don't distinguish acute impairment from residual THC left in a user's system after the high has worn off. Further complicating research is the frequent combination of both alcohol and marijuana use, which amplifies the effects of both drugs.

An Insurance Information Institute (III) report recognized the "It's Complicated" state of marijuana/traffic safety research, saying, "The relative recency of recreational marijuana legalization in some states makes it difficult to determine its overall real-world impact on traffic safety. Furthermore, different impacts on traffic safety between recreational and medical marijuana might exist."

III researchers summarized five key takeaways in the report:

1.     Marijuana affects users differently, but it generally impairs cognitive and motor skills.

2.     Marijuana impairment increases the risk of culpability for a car crash. Mixing marijuana and alcohol heightens risks.

3.     Marijuana use could increase after recreational marijuana legalization, and the number of THC-positive drivers could increase as well.

4.     Legalization is associated with an increase in collision-claim frequency.

5.     Fatal crashes involving drivers who tested positive for THC have increased, but it remains unclear how legalization impacts fatal crash rates.

To Point No. 1, we would add this: No impairment is good impairment, whether it comes from a recreational drug, sedating over-the-counter medication, lack of sleep or heightened emotional state.

Regardless of the "why," the most important question for any driver is, "Can I safely control my car?"