# Marijana and Driving Stats **URL:** \ **Category:** Factual Questions\ **Created:** [June 21, 2018, 7:51pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532 "2018-06-21T19:51:15Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![The\_Flying\_Dutchman](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@The\_Flying\_Dutchman](https://boards.straightdope.com/u/The_Flying_Dutchman)\ **Post date:** [June 21, 2018, 7:51pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/1 "2018-06-21T19:51:15Z")
Late last night I entered into a facebook conversation while “stoned” but sober. The other person was drunk and incoherent a good part of the time. I’ve never been like that “stoned” and my friends who smoke pot and don’t drink are never like that. So I wonder about those who are providing stats on marijuana and driving if they separate the stats on marijuana and driving to isolate the marijuana only drivers from those who also had a drink. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [June 21, 2018, 8:04pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/2 "2018-06-21T20:04:59Z")
There a large NHTSA study here; the only qualification I can see on a quick scan is that it was restricted to a single location. DOT HS 812 355 Drug and Alcohol Crash Risk: A Case-Control Study Lacey et al, 2016 pdf: [https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812355\_drugalcoholcrashrisk.pdf](https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812355_drugalcoholcrashrisk.pdf) > [@](#): > > Unadjusted drug odds ratio estimates indicated a significant increase in crash risk. For the active ingredient in marijuana, delta-9-tetrahydrocannabinol (THC), this yielded an unadjusted odds ratio of 1.25. However, **after adjusting for gender, age, race/ethnicity, and alcohol, there was no indication that any drug significantly contributed to crash risk. The adjusted odds ratios for THC were 1.00, 95 percent CI [.83, 1.22], indicating no increased or decreased crash risk**… That’s good evidence that you’re correct. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [June 21, 2018, 8:12pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/3 "2018-06-21T20:12:09Z")
But then there are a whole bunch of studies and meta-analyses that show THC use inreases accident risk, listed here. I’m looking through some of them to see how they control for alcohol. [https://www.drugabuse.gov/publications/research-reports/marijuana/does-marijuana-use-affect-driving](https://www.drugabuse.gov/publications/research-reports/marijuana/does-marijuana-use-affect-driving) Also, it strikes me that in the first study I mentioned, the power of the study might be considerably weakened by the fact that THC lasts a long time in the system, so many people who are not actually “high” would be positive for THC. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [June 21, 2018, 8:14pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/4 "2018-06-21T20:14:41Z")
> [@Riemann](#): > > But then there are a whole bunch of studies and meta-analyses that show THC use inreases accident risk, listed here. I’m looking through some of them to see how they control for alcohol. > > [Does marijuana use affect driving? | National Institute on Drug Abuse (NIDA)](https://www.drugabuse.gov/publications/research-reports/marijuana/does-marijuana-use-affect-driving) www.drugabuse dot gov? I’m sensing this site _might_ lean slightly to a certain side of the debate. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [June 21, 2018, 8:21pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/5 "2018-06-21T20:21:28Z")
> [@Czarcasm](#): > > www.drugabuse dot gov? I’m sensing this site _might_ lean slightly to a certain side of the debate. I’m not relying on what they say, they cite a long list of relevant research, including the one I cited that shows no increased risk from THC. I don’t get any sense of bias or cherry-picking, but if you have a more comprehensive list of research, please post it. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [June 22, 2018, 2:21pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/6 "2018-06-22T14:21:47Z")
There was an item in this morning’s newspaper that Canada would revise its laws to permit random breathalyzer tests on anyone without any evidence of impaired driving but would permit saliva tests for DHC only when there was such evidence. The reason for the first change was that jurisdictions that had done so had reduced accident rates and that it wasn’t extended to DHC because the evidence that it caused impaired driving was less than compelling. And this was a government report that made that statement. So I think that it is fair to say that the jury is still out on that one. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [June 22, 2018, 2:38pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/7 "2018-06-22T14:38:16Z")
There’s always been a running joke in my circle of pot smoking friends that pot makes you a MORE cautious driver (The joke being that it’s due to paranoia. The stoned driver is extra careful not to break any traffic laws so they don’t get pulled over.). I don’t know if the science backs that up, but it doesn’t sound completely untrue to me. ---
**Author:** ![Channing\_Idaho\_Banks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/channing_idaho_banks/32/250_2.png) [@Channing\_Idaho\_Banks](https://boards.straightdope.com/u/Channing_Idaho_Banks)\ **Post date:** [June 22, 2018, 3:13pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/8 "2018-06-22T15:13:43Z")
I have passed out from too much pot. It’s a good thing that didn’t happen while I was driving. ---
**Author:** ![Procrustus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/procrustus/32/2994_2.png) [@Procrustus](https://boards.straightdope.com/u/Procrustus)\ **Post date:** [June 22, 2018, 3:30pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/9 "2018-06-22T15:30:02Z")
> [@Grrr](#): > > There’s always been a running joke in my circle of pot smoking friends that pot makes you a MORE cautious driver (The joke being that it’s due to paranoia. The stoned driver is extra careful not to break any traffic laws so they don’t get pulled over.). > > I don’t know if the science backs that up, but it doesn’t sound completely untrue to me. I have a study done at the University of Limburg in the Netherlands, published by NTIS, (US Dept of Commerce) that concludes: > [@](#): > > This program of research has shown that marijuana, when taken alone, produces a moderate degree of driving impairment which is related to the consumed THC dose. The impairment manifests itself mainly in the ability to maintain a steady lateral position on the road, but its magnitude is not exceptional in comparison with changes produced by manly medicinal drugs and alcohol. Drivers under the influence of marijuana retain insight in their performance and will compensate where they can, for example by slowing down or increasing effort. As a consequence, THC’s adverse effects on driving performance appear relatively small. ---
**Author:** ![bardos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bardos/32/1069_2.png) [@bardos](https://boards.straightdope.com/u/bardos)\ **Post date:** [June 22, 2018, 6:35pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/10 "2018-06-22T18:35:14Z")
> [@Grrr](#): > > There’s always been a running joke in my circle of pot smoking friends that pot makes you a MORE cautious driver (The joke being that it’s due to paranoia. The stoned driver is extra careful not to break any traffic laws so they don’t get pulled over.). > > I don’t know if the science backs that up, but it doesn’t sound completely untrue to me. The devil with “scientific” studies… they are a bad joke when it comes to psycho-active substances. The data I will share here is personal experience personally experienced. If you remember when you first learnt to drive, it will become clear. Same thing as learning to ride a bike really. You begin trying to _think_, using your mind to calculate every move of hands, feet and vision. An overload really, which slowly, slowly after some experience moves into what humans often call “muscle memory”, where they can drive a car and think about other stuff like paying their bills or what they saw on TV last night or even have a conversation with the person in the passenger seat. In this scenario, the car begins to drive itself, as your mind’s attention can be elsewhere. Anyone ever "wake up"after a long highway stretch and wonder how they had driven the past few miles or kms without really paying attention? The body was driving the car and keeping it in lane. What happens when one has ingested a psycho-active substance like cannabis is that this situation becomes reversed and “muscle memory” is no longer in charge. It’s as if you were just learning to drive again and the mind is forced into assuming command. At this point there is just too much data to keep track of with the mind alone. As in your first times behind the wheel. And thus you are literally obligated to drive slowly in order to process all the incoming impressions. Conclusion is that the best driving is done without the mind. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [June 22, 2018, 8:15pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/11 "2018-06-22T20:15:41Z")
> [@Procrustus](#): > > Drivers under the influence of marijuana retain insight in their performance and will compensate where they can, for example by slowing down or increasing effort. My anecdotal evidence seems to agree with this quote Procrustus found. AI’ve often heard potheads say “I’m sooooo stoned”, but then the obvious drunks say “I’m not drunk! I can drive fine!”. ---
**Author:** ![TaoPilot](https://avatars.discourse-cdn.com/v4/letter/t/77aa72/32.png) [@TaoPilot](https://boards.straightdope.com/u/TaoPilot)\ **Post date:** [June 23, 2018, 2:12am UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/12 "2018-06-23T02:12:34Z")
> [@Grrr](#): > > There’s always been a running joke in my circle of pot smoking friends that pot makes you a MORE cautious driver (The joke being that it’s due to paranoia. The stoned driver is extra careful not to break any traffic laws so they don’t get pulled over.). > > I don’t know if the science backs that up, but it doesn’t sound completely untrue to me. A drunk driver speeds through a stop sign. A stoned driver stops and waits for the stop sign to turn green. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [June 23, 2018, 2:59am UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/13 "2018-06-23T02:59:14Z")
One difference is that alcohol affects inhibition and executive function, meaning drunks will make worse decisions and aren’t as constrained by judgment as you would usually be. And of course in some people alcohol makes them aggressive. A very bad combination. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [June 23, 2018, 1:56pm UTC](https://boards.straightdope.com/t/marijana-and-driving-stats/816532/14 "2018-06-23T13:56:25Z")
I won’t drive if I smoke pot because I can’t drive safely. maybe i am, the only one but I doubt it. My depth perception goes out the window as does my concept of speed. reacting and making a quick maneuver is greatly affected also.