If the data holds true, the chance of marijuana failing to pass the legal test in states that have yet to open its doors could become minuscule at best. But as the country goes in the direction of legalization, there needs to be more public education about not consuming marijuana before driving, he said, suggesting the cannabis industry needs to take an active role in that.
Legal recreational marijuana sales in Colorado began in January 2014, while Washington followed six months later, and OR began in October 2015. OR voters approved legalized recreational marijuana in November 2014, and sales started in October 2015.
While this certainly isn't an endorsement for de-legalizing recreational marijuana use, it is a reminder to stay off the roads if you're having your head changed.
Beyond that, the two studies used different baselines for comparison.
The HLDI noted that its study examined claims from January 2012 through October 2016 for vehicles between 1981 and 2017 model years. Analysts controlled for differences in the rated driver population, insured vehicle fleet, the mix of urban versus rural exposure, unemployment, weather and seasonality. The Insurance Institute for Highway Safety has started a large case-control study in OR to see how legal cannabis affects the risk of injuries in collisions. Since it only investigated collision claims with insurers, crashes kept off the books are obviously not included. Colorado legalized marijuana in 2014.
The Institute's Moore defended its approach, saying, "We looked at the correlation of states with similar insurance claim frequencies, and the states we chose had the highest correlation".
As for advocates of marijuana legalization, they say there is still little to no evidence proving the use of marijuana caused any crashes.
Washington saw a more than 6 percent increase, and OR had a more than 4.5 percent increase.
Indeed, the results are a "good representation of the effect of marijuana legalization overall", IIHS notes. In the end, the group compiled data from 20 states that was deep enough to allow a rigorous analysis. After Colorado legalized retail marijuana, the uptick in collision-claim frequency was 14 percent higher than in adjacent Nebraska, Utah and Wyoming. According to data from the Highway Loss Data Institute (HLDI), that's exactly what's happening.
Clearly, more research would help.
HLDI gathered data from Colorado, Oregon and Washington, states which have recently legalized marijuana for recreational use.
"Our study focused on deaths and actually found what we expected going into this", Jason Adedoyte, a trauma surgeon and lead author of the study, told Reuters.
Investigators from the University of Texas-Austin evaluated crash fatality rates in Colorado and Washington pre- and post-legalization. As more adults use marijuana now that it is legal, he believes his deputies will have to deal with more crashes.
Interestingly, statistics provided by the state of Colorado did not agree with the study.