Is there a full study somewhere? I'd expect them to screen for other psychoactive substances as well, of which I see no mention here.

One useful point of comparison here would be the percent of the driving population overall who have some THC in their system in the same way as these researchers are measuring it. I wouldn’t guess that 40% of drivers would test positive for recent THC use, but I can’t understand the 40% number here without knowing the percent for the overall population.

Does anyone else constantly smell weed while driving around? Several times per week I find myself behind a car that wreaks so bad of weed that I can clearly smell it driving a few car lengths behind. I have to wonder…if so many people are smoking enough to smell it in another car while moving, exactly how many people on the road are high?

Here in New Zealand we’ve just started road-side testing for drug-driving [0]

0. https://www.rnz.co.nz/news/national/581951/first-day-of-road...

I have it on good authority and a lot of data that over 40% of deceased drivers in vehicle crashes test positive for recently having (i) breathed air containing oxygen, (ii) drank tap water (iii) were wearing shoes, (iv) had used those shoes to get to the car, ...

I saw this and it was too funny:

  Over 40% of deceased drivers in vehicle crashes test positive for THC: Study (facs.org)
  281 points by bookofjoe 15 hours ago | flag | hide | 420 comments
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“Unaffected by legalisation” - so at least there’s more proof than outlawing drugs doesn’t work.

This stat beggars belief. I think the headline is phrased incorrectly, and the overall stat is misleading. The actual stat is only from dead drivers who were tested for THC.

    Researchers analyzed coroner records from
    Montgomery County in Ohio from January 2019
    to September 2024, focusing on 246 deceased
    drivers who were tested for THC following a
    fatal crash. When autopsies are performed,
    drug screening is typically part of the
    process.

The unanswered and unaddressed questions here are, how often and why were the THC tests administered? The article says that’s standard for autopsies. But how often are autopsies conducted on deceased drivers? I would be truly surprised if it’s 100%. In fact, I would expect it to happen only in cases where there was some suspicion of intoxication. In which case, this finding isn’t very surprising after all.

Rather than trying to draw policy conclusions from an epidemiological study like this, wouldn't it be more accurate to give drivers measured amounts of THC, put them in a driving simulator, and measure their performance?