Toking and driving is still a bad idea, but that old adage that a stoned driver is safer than a drunk driver? Turns out it’s true.

Traffic Deaths and Marijuana Legalization

The states that have legalized medical marijuana have also experienced a drop in traffic fatalities that can be directly linked to the change in policy, according to a study released earlier this year. The results of the study were featured in a report in The Boston Globe in August.

A group of economists published a paper in the Journal of Law and Economics in May that examined the connection between traffic deaths and marijuana legalization in the various states that allow medical pot. On average, they found that traffic fatalities dropped by 8 to 11 percent within a year after marijuana laws took effect and by 10 to 13 percent within the first four years.

The study doesn’t prove one way or another exactly what caused the drop, but there is a tie to the new pot laws, and the researchers believe people who would normally be drinking and driving are using weed instead. For example, the drop in deaths is strongest among young adults, at night and on the weekends, which correlate to drunk driving fatalities.

“The uncomfortable conclusion is that you’d rather have young adults smoking marijuana instead of drinking alcohol,” said Daniel Rees, a University of Colorado economist and one of the authors of the study. “Even I’m uncomfortable with it. But that’s where the logic takes us.”

Theories For The Correlation

The researchers have a couple theories about what happens when drivers substitute pot for booze.

On the one hand, it’s possible the drinkers who have switched to pot are now staying at home. Alcohol is a legal, socially acceptable drug that is consumed primarily in public, whereas marijuana still carries a stigma and is primarily used at home. So smokers who had somewhere to go when they drank may no longer be driving.

On the other hand, it’s possible the same people are driving impaired, but are doing a better job of it. In fact there’s additional research to back this up.

“I think they have a really interesting finding. But this is just the tip of the iceberg. It’s not, aha, we have it!”

Rosalie Pacula, economist at the RAND Corp.

Studies show pot and alcohol are equally bad for distance perception, reaction time and hand-eye coordination, but stoned drivers perform much better in simulated and real-world driving tests than drunk drivers. In fact, while high drivers carry nearly double the risk of crashing compared to sober drivers, the risk is tenfold for drivers over the legal alcohol limit. And stoned drivers tend to engage in “compensatory behaviors” that reduce risk, such as slow driving and maintaining excessive distance.

Other researchers point out that more study is needed. Other details hidden in the numbers complicate the picture further.

For example, Rosalie Pacula, an economist at the RAND Corp., analyzed the same information and found the states that do the best job preventing medical marijuana from spilling over into the black market experienced the greatest declines in traffic fatalities. This conflicts with the argument that drinkers are switching to weed, since in that case the results should be strongest where pot is most widely available.

“I think they have a really interesting finding,” said Pacula. “But this is just the tip of the iceberg. It’s not, aha, we have it!”


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