Higher Crash Rates Exist In States With Legalized Recreational Marijuana

July 31, 2017

The Highway Loss Data Institute reported higher collision rates in Washington, Oregon and Colorado since recreational marijuana was legalized. Many drivers admitted to using marijuana, and it is a documented problem more often among people who are in crashes. While researchers have not yet definitively connected marijuana to increased crash rates everywhere, they have performed studies that show how marijuana degrades aspects of driving performance. In some studies, people who used the drug were twice as likely to crash, and some studies did not show a significant risk. Studies focusing on medical marijuana and driving have remained inconclusive. 

In 2012, Washington and Colorado were the first states to approve legalization of recreational marijuana for anyone over the age of 21. Sales did not start until 2014. In Oregon, sales started in 2015. To provide control in their recent study, HLDI used data from the three states where marijuana was legal as well as data from neighboring states. The control states included Nevada, Wyoming, Utah, Idaho and Montana. To strengthen their findings, the researchers also used data that was collected prior to 2014 in Washington, Colorado and Oregon. Notes were made for different years and each state's status of legalized medical marijuana. It was not permitted in certain states at any point.

HLDI examined each state's loss results after recreational marijuana legalization took place and compared them with the loss results of neighboring states where marijuana was not allowed for recreational use. Researchers looked at the data from claims that were filed between the beginning of 2012 and the end of 2016. Also, they looked at model years of vehicles and recorded any cars that were made between 1981 and 2017. There were analysis controls in place for insured vehicle fleet, driver population ratings, urban versus rural surroundings, seasons, weather and unemployment. 

The most popular type of claim filed today is a collision claim. Collision insurance protects at-fault policyholders from paying for physical damage to another driver's vehicle if there is a crash. Collision claim frequency is calculated by dividing the amount of collision claims by the duration of vehicle insurance, which is measured in years. According to crash data, Colorado saw the biggest increase in claim frequency. In comparison with its neighboring states of Nebraska, Wyoming and Utah, Colorado's crash rate was 14 percent higher. Although Oregon and Washington did not have large disparities in comparison with neighboring states, crash rates were still higher. 

The new analysis from HLDI about marijuana and accidents gives a look at the effects of legalization on highway safety, and researchers said that it should tell other states what decriminalizing marijuana may bring. HLDI plans to continue examining claims and marijuana-related accident data in the future to connect any trends. The Insurance Institute for Highway Safety is also working on a case-control study to analyze the changing crash risks in Oregon, and it will be completed in 2020. Several other states have recently passed legislation to decriminalize marijuana, and more are expected to do so in the near future. 

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