Legalising cannabis hasn’t made roads any less safe, finds study

New findings shed light on the relationship between cannabis legalisation and road safety in the United States. 

Analysis of data from states that legalised cannabis in 2016 found that traffic fatalities remained stable or decreased in the three years following legalisation, as compared to a slight increase in states where cannabis remains illegal.

Researchers at Quartz Advisor, which conducted the study, collected data on four states that fully legalised cannabis in 2016: California, Maine, Massachusetts, and Nevada. 

The primary metric used was deaths per 100,000,000 vehicle miles, sourced from the National Safety Council (NSC). 

These states’ vehicle death rates were compared to those of five states that have not legalised cannabis, including Idaho, Indiana, Kansas, Nebraska, and Wyoming.

After excluding data from 2020 and 2021 (which were found to be anomalies as traffic fatalities increased significantly nationwide) none of the states that legalised cannabis saw increased traffic fatality rates from 2016 to 2019.

Analysis found that the states that legalised cannabis in 2016 experienced an average 11.6% decrease in vehicle death rates over the next three years—a point higher than the national average of 10.6%.

Credit: Quartz Advisor

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Researchers also contacted insurance regulatory agencies and examined data from the US and Canada. 

Despite being a more exhaustive analysis, it yielded similar results, failing to detect a statistically significant increase in accidents and fatalities due to cannabis legalisation.

Judi Watters, of the Maine Bureau of Insurance, told the authors that there have been no significant changes in insurance laws or industry trends due to cannabis legalisation in Maine.

A report from the Casualty Actuarial Society (CAS) also found no statistically significant changes in traffic safety related to marijuana legalisation in the US and Canada.

While cannabis is known to impact cognitive and motor skills, previous studies have found that legislation does not translate into significantly riskier driving behaviour. 

By comparison, alcohol remains a major factor in traffic fatalities, contributing to three out of every 10 traffic deaths between 2012 and 2021.

A press release issued on behalf of Quartz Advisor said: “Marijuana’s impact on road safety is not a significant concern, especially when compared to alcohol, which remains a prominent contributor to traffic fatalities. 

“With marijuana legalisation continuing to be debated across the globe, these findings provide valuable insights for informed decision-making.”