A new study conducted by Quartz Advisor has found that states that legalized marijuana in 2016 experienced significant declines in traffic fatalities in the years immediately following the policy change. The study compared traffic fatality data from four states that legalized adult-use cannabis in 2016 (California, Maine, Massachusetts, and Nevada) to the national average as well as to rates in five states where marijuana remained illegal (Idaho, Indiana, Kansas, Nebraska, and Wyoming).
Over the three-year period following legalization, none of the four legalized states saw an increase in traffic deaths. In fact, most of them experienced declines. Massachusetts saw the biggest drop, with rates falling by 28.6 percent in the three years following legalization. Overall, the four states that legalized marijuana saw an 11.6 percent drop in traffic death rates from 2016 to 2019, which is higher than the national average decline of 10.6 percent during the same period.
However, when researchers expanded the analysis to include data from 2020 and 2021, they found that vehicle death rates actually rose in states that legalized marijuana, although at a lower rate than the national average. On the other hand, states where cannabis remained illegal saw a decrease in vehicle fatality rates during those years.
The study acknowledges that 2020 and 2021 were anomalous years for traffic accident trends due to various factors. The U.S. as a whole saw an 18.9 percent increase in traffic fatality rates during this period, while states that legalized marijuana saw a similar increase of 19.9 percent. States that have not legalized cannabis experienced a 2.3 percent decrease in vehicular death rates.
The study cautions against drawing definitive conclusions from these recent years and emphasizes that the findings are limited and nuanced. It also cites a report from the Casualty Actuarial Society in December 2022, which found no statistically significant change in fatalities or claim frequency after marijuana legalization in the U.S. and Canada from 2016 to 2019.
While the study suggests that there is no evidence to suggest that legalizing or decriminalizing marijuana makes roads more dangerous, it also highlights the importance of not driving under the influence of cannabis. A meta-analysis published in The American Journal of Addictions found that marijuana causes impairment in various performance areas associated with safe driving.
However, the study notes that despite cognitive impairments, many marijuana-intoxicated drivers show only modest impairments on actual road tests. Experienced smokers who drive on a set course exhibit almost no functional impairment under the influence of marijuana. This discrepancy between cognitive studies and real-world driving behavior adds complexity to the issue of cannabis-impaired driving.
One challenge in addressing cannabis-impaired driving is the lack of a reliable test to specifically screen for cannabis impairment. Standard drug tests cannot determine whether someone is currently under the influence of marijuana or had consumed it days or weeks ago. Efforts are underway to develop objective standards and field sobriety tests to measure marijuana impairment and ensure highway safety.
In conclusion, while states that legalized marijuana in 2016 did not experience significant increases in traffic fatalities compared to states where it remained illegal, the overall picture becomes muddier when recent years are included. The study emphasizes the need for further research and caution regarding driving under the influence of cannabis.
