Does marijuana impair one's ability to drive?

The question speaks for itself.

It certainly alters your perception. How it does so varies quite a bit between people. For some people it will impair their ability quite a bit, for others not so much.

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Since this kind of question belongs in General Questions, not About This Message Board, I’ll move it for you.

twickster, moderator

Yes, it can.

It does not have to. if you feel too high just drink some beer to mellow out and you will be fine.

I used to drive stoned. I found at first that it heightened my senses and my awareness of my surroundings, causing me to drive much more cautiously. I even got pulled over by the cops when I was off my tree due to a failed tail-light, and got away with it.

After a couple of years of doing it, however, I became more confident; I then began to realise that though my motor skills and reaction times were completely OK or - and I tested this with a ‘reaction time’ program on a computer - better than normal, my judgement in certain situations was markedly impaired. On one occasion I tried to overtake someone in an underpowered vehicle when it was not safe to do so, and had to abort the procedure at the last second to avoid a head-on collision. It scared me so much I never did it again.


‘You realise that you’re f*cked up, so you let your hands drive as if you were straight.’

Calling Dio

If it doesn’t, you should ask for your money back.

Here’s the NORML site on the topic with lots of good links:

The jist of most of them is that marijuana does indeed impair your motor skills but significantly less so than alcohol. And what Johnny LA says is actually somewhat true-- in tests on closed tracks, drivers who were drunk did much worse partly because they didn’t think they were very impaired, whereas the marijuana group specifically tried to drive more carefully because they knew they were impaired.

That said, I don’t think there’s anyone who says driving while high is a good idea, NORML included.

We talking racing video games or real life here?

Yup! When you drive, you should be reasonably alert, able to respond to multiple stimuli, and have good motor controls. Marijuana is intended to make you really relaxed; that impedes all the aforementioned skills.

Driving while stoned is illegal in lots of countries, even those that decriminalise marijuana, like the Netherlands. (This cite’ll probably suffice).


Of course it does. Maybe not as dramatically as alcohol, but it definitely has an adverse effect on your ability to focus on the task at hand and respond appropriately.

The very last time I consented to drive with someone with whom I’d recently smoked a big joint (almost twenty years ago? Really?) we ended up rear-ending someone on a side street. Buddy had turned 180 degrees around because he was intent on an anecdote he was relating to us in the back seat, and oblivious us to the three of us saying “Hey, hey, hey! [There’s a car stopped at a stop sign ahead!]”

More personally (by inference from flight simulations and video games, ability goes waaay down.

Any time you bump into someone who says that pot just makes you more cautious or than it makes their senses keener (“If there’s one thing I know how to do, it’s drive when I’m stoned!” just remind yourself that they are idiots and it wasn’t so long ago that every other idiot held the same attitude about alcohol.

The question is, would you want your family riding in a bus driven by a stoned bus driver?

I remember seeing a study a long time ago (probably over 20 years back) of the effect of pot on motor skills. It turned out that people were actually better at things like typing and playing musical instruments while under the influence, but only if they were used to smoking and they already had the skill; inexperienced smokers and/or people trying to learn a new skill while smoked up didn’t fare very well.

I don’t think the study covered driving, though. These days it is probably too un-PC to suggest the effects might not be all bad.

I recall seeing a show about 20 years ago or so, in which a group of ten people took turns manoeuvering a car through an obstacle course on a closed track.

The group was split up with half the group doing a shot in between runs through the course and the other half smoking weed in between.

The subjects smoking joints in between runs got progressively better and better scores while the shot drinkers just deteriorated to the point where they had problems getting the key into the ingnition.

That’s not to say that pot has no effect on how you drive, but to classify it as an equal to alcohol is way off base.

A lot of things can have just as much of an impact on your driving abilities as pot…

Too much caffeine
Not enough caffeine
A bad cold or cough
Just lost your job
Impending court date
Ongoing divorce
Nasty fight with spouse
Tuna sandwich at lunch with the mayo that was a little off
Allergies. Try getting a sneezing fit in the middle of rush hour traffic
Kid kicked out of school, missing, pregnant, arrested etc.

We’re going to need a lot more Mother’s Against groups down the road.

Cite for the pot-smoking drivers improving?

I don’t know about the US, but in the UK, if those events cause you to drive carelessly, you can be charged with ‘driving without due care and attention.’ If it were known that they definitely do affect everyone negatively, and they could be tested for, then maybe there’d be specific laws against them too - but that’s not the case.


One of the main effects is a dramatic reduction in short-term memory while one is high. One day I was driving on the highway while stoned and noted a vehicle overtaking me and entering my blind spot. A few seconds later, I tried to switch lanes, and almost crashed right into the guy. * I had totally forgotten he was there*. :eek:

I have never driven stoned again since that happened.

I’m not sure why the question is asked, as it is virtually self-evident that a substance that’s ingested for the purpose of altering reality in some way would, in fact, alter one’s ability to negotiate in that altered reality. It is usually referred to as a drug, right? Whatever the effects of pot are for you would apply during the truly complex act of driving. If things seem different to you when you’re stoned, then operating a car would similarly be affected by being stoned. (Anecdote): Most people report that they’re extra cautious when driving high. A friend of mine was driving high once and in an effort to exercise what he knew should be due caution and extra responsibility (being aware he was stoned) when approaching a stop light stopped a little before the light. I’d say he stopped about 50 - 75 feet before the light. This is the lighter side of paranoia.
Don’t get high and drive.