Traffic fatalities increase after cannabis legalization, study says

Researchers have found an increase in traffic fatalities in three states Colorado, Washington, and Oregon after recreational marijuana use was legalized. Specifically, researchers examined the effect of recreational cannabis sales (RCS) on traffic fatalities.

The researchers from Monash University, looked at the number of additional deaths each month after legalization, and found there was on average one additional traffic fatality per million residents, in comparison to states that had not changed cannabis laws. The increase was temporary, seeming to last for about a year following legalization. The combined population of affected areas is 27 million people, suggesting an additional 170 deaths in the first six months after legalization.

But the study reported the spill over effects to be slightly larger in neighboring states and provinces, particularly those with population centers closest to the border of a legalizing state – possibly because cannabis users were driving interstate to make purchases, before returning under the influence.

It’s called ‘cannabis tourism’, and Monash University’s Dr Tyler Lane says there are important implications for both legalizing states and their neighbors as prohibitions against cannabis use are lifted globally.

“The effect of cannabis legalization on traffic fatalities is a growing public health concern,” Dr. Lane said.

“The results suggest that legalizing the sale of cannabis for recreational use can lead to a temporary increase in traffic fatalities in legalizing states. This spills over into neighboring jurisdictions through cross-border sales, trafficking, or cannabis tourists driving back to their state of residence while impaired.

“Our findings suggest that policymakers should consult with neighboring jurisdictions when liberalizing cannabis policy to mitigate any deleterious effects.”

Dr. Lane said the findings were in contrast to research on medicinal cannabis suggesting it decreases traffic fatalities.

One reason for the difference may be that medicinal users tend to substitute cannabis for other substances, including alcohol, which has a greater effect on impairment. Recreational users are less likely to substitute and more likely to combine alcohol and cannabis, which has a much bigger effect than either in isolation.


  1. “Post hoc ergo propter hoc” seems to be the attempted point of that alleged research.
    The rooster crows; the sun comes up; therefore the rooster crowing makes the sun come up.
    Nope, pretty bad reasoning.
    What would be significant would be if drivers found in accidents had some evidence of having smoked marijuana.
    If there were such evidence, it is not mentioned in that article.
    What is mentioned, though, is that the traffic fatalities numbers decline some time after marijuana legalization.
    Doesn’t that, then, imply that the sooner marijuana is legalized, the sooner traffic fatalities will decline?
    Even beyond the immorality and impracticality of prohibition.

    • No it does not IMO. This information has been out for some time but is now only making it to this site it seems. Remember the promises made that all funding would be directed to the schools in colorado? Then the counter ad here in az that we dont need this stuff legalized? Well folks my son is a teacher IN colorado and he said they NEVER any of the supposed $$ from legal MJ! They ask for $$ but get a run around. They have compared legal drug to alchol sales, say it will bring in big $$, so far there has been little evidence of that and ILLEGAL sales continue.

      This is just another idea of the left to get folks that dont think on their side of issues, and they really dont care about any consequences.

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