Marijuana Might Make You a Worse Driver Than Alcohol Does


Young women smoking marijuana on the banks of the Frio River

We thought the question “Is It More Dangerous To Drive Drunk Or Stoned?” had already been definitively answered in favor of alcohol being the more dangerous (although we did find a study suggesting “Smoking Marijuana Nearly Doubles Risk Of Driving Accidents“), but in a New Republic review of yet another study it seems that the answer is less black and white than had previously been thought:

Supporters of legal marijuana, medical or otherwise, are fond of pointing out that marijuana is less deadly than alcohol. Even President Obama’s deputy drug czar admitted as much in February. That doesn’t mean pot is harmless: USA Today reported Tuesday that marijuana’s role in traffic fatalities tripled between 2000 and 2010, according to Columbia University researchers. But driving stoned is still safer than driving drunk, right? Don’t be so sure.

In 2000, researchers at Maastricht University in the Netherlands gave driving tests to subjects who had consumed various amounts of alcohol and/or marijuana. While all subjects both drank and smoked in each round of the study, some were given placebos, so that the researchers were able to test the effects of each substance on its own as well as their combined effect. They measured drivers’ “standard deviation of lateral position” (SDLP), or the distance they drifted out of their lane, and also the time out of lane (TOL).

The study found that alcohol on its own increased SDLP by 2.2 centimeters (as compared to double-placebo conditions). Marijuana, depending on the dosage of THC (100 or 200 micrograms per kilogram of body weight), increased SDLP from placebo conditions by 2.7 and 3.5 centimeters respectively. In other words, drivers who had smoked pot were less able to drive in a straight line than drivers with an elevated BAC. (Most drivers’ BACs fluctuated around 0.04 grams per deciliter, below the legal limit of 0.08.)

The researchers concluded that the percentage of TOL was not significantly affected by either alcohol or marijuana alone, but that it was much higher when both substances were used together…

[continues at New Republic]


Majestic is gadfly emeritus.

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24 Comments on "Marijuana Might Make You a Worse Driver Than Alcohol Does"

  1. My own experience, with self and others does not agree with this. But who cares, texting drivers are worse than either pot or alcohol, so until that’s effectively dealt with, it doesn’t matter too much. Now we have to get killed or injured because someone desperately had to send a message of “U mad? LOL”

    • リカルド 忍者の心 | Jun 12, 2014 at 8:34 am |

      My own experience is same as yours, but when one’s not well experienced with driving (e.g., just after learning to drive) or/and is not very experienced with pot, things can get dangerous.

      • Imagine new drivers who text while driving!


        • Ugh.

          New pedestrians who text while walking are the worst.

          Hello there! I need to occupy an area of physical space on this concrete embankment. You may have mistakenly thought otherwise, being absorbed in your mobile serotonin trigger. But ÿ assure you it is true.

          Clearly, the solution is to militarize the pedestrians with aluminum bats. Not for each other, mind you, but for all the fucking krzzzy apes on wheels!

          How’s my driving?
          *recovers from being sideswiped*
          *smashes all car windows*

          ¡Make it so!

  2. Obviously this depends on the person and dosage and I would still call bullshit on this study. I dont smoke weed or drink alcohol these days and dont condone driving under the influence of either, but have done it in my past. When I was younger for years I smoked large amounts of 20+% THC high grade chronic and drove on a regular basis and got in no accidents or pulled over and was fully capable of driving in a straight line. Now alcohol was a different story and I have only drove drunk a couple times and never would ever again cuz almost crashed one of those times and it scared me. Like I said though I dont condone doing either one and driving, those were my younger stupider days and driving is a dangerous enough thing even if you dont have a bunch of high or drunk people on the road. And dont even get me started on fuckers talking on their cellphone or texting and driving they are many times WORSE than someone under the influence.

    • Number1Framer | Jun 12, 2014 at 12:18 am |

      Back when I used to drive stoned, I had a strategy of always sticking to
      country backroads and assuming every single car on the road was a cop. I never
      sped, got in an accident, hit a deer, or had any sort of police
      interaction what so ever as a result of stoned driving. One of my
      friends on the other hand, would apparently lose the ability to see red,
      octagonal road signs whenever he was high. Can’t count the number of
      times telling him “hey dude, there was a stop sign there,” before that
      morphed into “let’s take my car, I’ll drive.” As you said: person and dosage. We’re all affected differently by any substance.

      • I agree. I have met people who act incredibly retared on weed and probably should never touch it, Its not for everyone. Plus like I was saying these days I dont really agree with driving and smoking weed or driving and drinking or the bigger problem now is driving and talking on cellphone or texting.

        • Number1Framer | Jun 12, 2014 at 12:50 am |

          I’ve always fantasized about getting a cellular jammer and hiding it under the seat of my car just so when I’m stuck in interstate rush hour gridlock I’d have the shocked faces of the drivers on either side of me for entertainment. But alas, they are illegal in most circumstances (this of course being one).

          • The only thing that makes it illegal is getting caught 😉

          • Jamming is seen as property theft, because a private company has purchased the rights to the radio spectrum, and jamming the spectrum is akin to stealing the property the company has purchased. It also represents a safety hazard because jamming blocks all calls in the area, not just the annoying ones. Jamming a signal could block the call of a babysitter frantically trying to contact a parent or a someone trying to call for an ambulance.

            The Federal Communications Commission is charged with enforcing jamming laws. However, the agency has not yet prosecuted anyone for cell-phone jamming. Under the U.S. rules, fines for a first offense ca­n range as high as $11,000 for each violation or imprisonment for up to one year, and the device used may also be seized and forfeited to the government.

            (Via: ) Emphasis is author’s

            Smells like a job for Uncle Homeland℗. I’m sure some military-industrial think-tank already has some kind of legal gibberish to connect owning a jammer to terrorism. Obama™ does have a challenging midterm election for “his” party & agenda coming up…

          • Haha ya I knew they were pretty serious laws on jamming and I do agree they probably will figure out some way to call you a domestic terrorist if you use it. The fact that the government feels it owns the electromagnetic spectrum and can actually sell it to a company so they can consider it “property” just shows yet another ridiculous aspect of our society.

          • thisbliss | Jun 12, 2014 at 5:51 pm |

            Hi ho Hi ho, monetise the commons we will go

          • InfvoCuernos | Jun 12, 2014 at 1:54 pm |

            wouldn’t the jammer be as dangerous a distraction as the cell phones?

          • I dont know much about them but im pretty sure once any settings are adjusted (which could be done before driving) that its just a on/off switch used so I would say that isnt near as distracting because you are not spending as much time messing with it or focused on the conversation you are having or text you are sending.

          • Number1Framer | Jun 12, 2014 at 9:05 pm |

            Accidentally jamming emergency frequencies could be a bit of a sticky wicket. It’s okay, never gonna get the chance to find out anyway.

  3. Amir Alwani | Jun 11, 2014 at 9:17 pm |

    “Studies Show Marijuana Consumption Not Associated With Dangerous Driving”

  4. ÿ suggest banning drivers from being under the influence of the following substances:

    red meat
    cell phones
    other people
    that russian zombie drug
    tin foil
    supply side economics
    the number e

    3 Strikes and you’re out. That should get the prison industrial complex onboard. The returns on the slave labor will more than pay for the enforcement mechanism! Also, think of the children. We can fix the schools (by turning them into charter schools).

  5. BuzzCoastin | Jun 11, 2014 at 11:15 pm |

    3 cm is 1.18 in
    so one toke over the line is an inch?

  6. VaudeVillain | Jun 12, 2014 at 2:19 am |

    Having driven after smoking weed, and also after drinking (yeah, I know, I suck)… both are shitty ideas and anyone who thinks either is alright is just flat out wrong. Don’t know which is worse, and I don’t care either.

  7. Gjallarbru | Jun 12, 2014 at 7:54 am |

    Could anyone tell me why there’s even a debate as to which is “worse”? Who cares which is worse, don’t drive if you don’t have a whole brain and that should solve the problem entirely.

  8. Damian Caligula | Jun 12, 2014 at 12:16 pm |

    Did they test drivers who are used to smoking marijuana? Or did they give high doses to people who’ve never tried it? If you have no tolerance for it, you shouldn’t be driving under the influence of it. For someone who has developed a tolerance to it, it would pose no problems to drive in a straight line.

  9. DeepCough | Jun 12, 2014 at 6:34 pm |

    I’ve had several accidents while sober, yet strangely, not a single one, NOT A ONE, whilst stoned. But I guess having a control group like me would’ve skewed the conclusion.

  10. Matt Staggs | Jun 17, 2014 at 4:05 pm |

    Please don’t insult the entire site for one contribution that made you angry. My own views on this matter might very much surprise you. As an aside, you have to admit that linking to a Yahoo article as “research” is pretty damned funny, not that I don’t think some skepticism is warranted.

    I see your name handle is “Ki’a Dragon”. Do you study a martial art? I do Brazilian Jiu-Jitsu.

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