After legalizing recreational use of marijuana, the states of Colorado, Oregon and Washington saw collision claim frequencies rise about 3% higher overall compared to neighbouring states, according to a new analysis from the Highway Loss Data Institute (HLDI).
“The combined-state analysis shows that the first three states to legalize recreational marijuana have experienced more crashes,” said Matt Moore, senior vice president of HLDI. “The individual state analyses suggest that the size of the effect varies by state.”
Washington and Colorado were the first states to legalize recreational use of marijuana for adults 21 and older in November 2012.
According to Heavy Duty Trucking, HLDI’s analysis relied on neighbouring states as additional controls to evaluate the collision claims activity in Colorado, Oregon and Washington before and after law changes. The control states included Idaho, Montana, Nevada, Utah and Wyoming, in addition to Colorado, Oregon and Washington before the legalization of recreational cannabis use, the institute said.
According to the HLDI, Colorado experienced the largest estimated jump in claim frequency, compared with its control states. After retail recreational pot sales began in the state, the collision claim frequency climbed to 14% higher than in nearby Nebraska, Utah and Wyoming. In Washington, the estimated increase in claim frequency was 6.2% higher than in Montana and Idaho. Oregon’s estimated increase was 4.5% higher than in Idaho, Montana and Nevada.
“The combined effect for the three states was smaller but still significant at 3%,” Moore said. “The combined analysis uses a bigger control group and is a good representation of the effect of marijuana legalization overall. The single-state analyses show how the effect differs by state.”
In response to the new analysis, Governors Highway Safety Association (GHSA) Executive Director Jonathan Adkins issued a statement reiterating the group’s stance that states should “consider the risk of marijuana-impaired driving as they move toward liberalizing marijuana laws.”
The GHSA cited recent national data that found marijuana was present in 12.2% of all fatally injured drivers who tested for drugs.
However, a study earlier this year published in the American Journal of Public Health found that crash fatality rates were not statistically different three years after legalization in Washington and Colorado compared to states that have not legalized marijuana. Researchers in that study noted that future studies should be conducted looking at longer term data.
Commercial vehicle drivers are still prohibited from using marijuana by Federal law, even in states that have legalized it, according to the Department of Transportation.