'Driving Under the Influence of Cannabis: An Increasing Public Health Concern'

'Experimental laboratory studies have repeatedly demonstrated that the primary component of cannabis (ie, of D9-tetrahydrocannabinol [THC]) impairs the motor performance (eg, reaction time, tracking) and cognitive function (eg, attention, decision making, impulse control, memory) needed for safe driving in a dose-related manner. Performance impairments are maximal during the first hour after smoking and decline over 2 to 4 hours after cannabis use.

‘In a policy brief by the World Health Organization, driving under the influence of cannabis was estimated to be responsible for slightly more than 8700 road traffic deaths worldwide in 2013. This is still far less than the number of deaths due to alcohol-impaired driving in the same year (slightly more than 188000)’

And, unfortunately, there is no road-side breathalyzer test for driving under the influence of cannabis.

It is also why many good paying jobs go un-filled. The applicant can’t pass a urine or hair test that shows cannabis use in the past. You’d really wouldn’t want your semi truck or forklift driver under the influence and employers can’t take the risk that the operator won’t still be affected from earlier use.

Difficult situation for states that have legalized cannabis use.

The last time we beat this dead horse I mentioned that legalization does not lead to increased use, so this isn’t likely to be more of a problem than it ever was.

If you’re going to smoke weed and drive, you’ll do it whether possession of marijuana is legal or illegal. The legal status of possession makes no difference in this outcome.

If you’re involved in a collision and test positive for marijuana, I wouldn’t want to be in your shoes, because you’ll likely face a civil suit whether the collision was your fault or not.

I don’t know about your insurance policy, but mine won’t cover me or my liability if I test positive for drugs after a collision.

In nearly all patroll cars over here (europe), they have an (I think you’ll call it a swab, you know, the cotton stick in your mouth, well, hopefully you don’t) analyzer. It will react on several different kinds of drugs. If they all are not green, you are gonna have a bad day.

Btw. Now you can get cannabis in certain countries in europe as a medical treatment, but the thc is removed, so no problem should occur with that part.

I don’t think the European test, if it tests for THC, is considered reliable here.


The US has medical cannabis products in many states as well. CDB based medical products that don’t contain THC.

That isn’t the question posed by the OP. It is driving under the influence of cannabis, the THC containing products. And my point was that many jobs go unfilled because employers can’t take the risk of hiring workers that use cannabis that shows in urine or hair because THEY can’t tell if their worker is currently high or just used last Saturday night for a bit of recreation.

In a former job, I saw 50 applicants for manufacturing jobs line up for their urine test and 48 get sent home for failing that test. So how does that work in a state that has legalized it for recreation or medicinal purposes. And some users use the full product medicinally. Apparently some state protect that use while others don’t. Job protections fall under federal law if the state hasn’t addressed it so employers can still test for cannabis even if it is legal in that state.


I have a nephew in Denver and he says you just go outside and you can smell it. So I’m not convinced that it being legal and available doesn’t lead to greater use. The anti-smoker coalition has been trying to limit the availability of tobacco just for that reason. I also am not sure that there aren’t long term and permanent affects on the brain from pot use. I have had this discussion with my neurologist son and he cautions about the long term effects. At any rate I still don’t think it should be illegal. (I have never used it or been in the same building where it has been used, except when we used to incinerate it for the Police.)

Now whether you are under the influence of alcohol, pot, diet pills, or whatever, it is the same thing and people need to recognize that. Even driving sleep deprived is the same. Just because detection methods may not be effective, we still need to recognize as a responsible driver, when we shouldn’t drive.

…and in my state where recreational marijuana is not legal I can smell it in my neighborhood. Anecdote means nothing.

Colorado was the mile high state long before they legalized recreational marijuana.

George, I hope it’s okay to quote you…

Aug '16

My favorite call was re-broadcast recently on Best of Car Talk, a lady from San Francisco wanting to know if it is possible to install a good AC and heating system in her 60’s VW Beetle. Tommy’s reply? " You live in San Francisco? Smoke a joint and forget about it!"
CSA :palm_tree::sunglasses::palm_tree:

There are also medical product that do contain THC. My sister needs THC for a medical condition, and just got her medical marijuana card. She won’t smoke it, and is looking for a way to convert the raw marijuana or a derivative to create THC. Don’t tell me how, we already know. She doesn’t need much in a dose for her condition, and prefers a couple of drops of infused oil in her food. No nasty tast, no lung problems, no getting high, and some much desired relief.

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What type of insurance do you have that they won’t cover? I understand that they insurance companies may deny coverage of YOUR property damage, but not liability coverage.

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Maybe I’m remembering it wrong, that they cover liability, but drop my coverage after that. In any case, it’s an outcome worth avoiding, so I’m not so focused on the details.

I would like to think that insurance companies treat cannabis use while driving the same way they treat alcohol use.

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I agree, @dagosa. Impaired is impaired, no matter how someone got that way. Happy to see you posting. How’s the farm?

I hear you @jtsanders. This is one time where the field test may be more important then a generalized blood or breathalyzer, even if either were available for cannabis. The “ farm” is fine. Thanks for asking. :wink: