If Marijuana Causes Lots of Crashes, Why Are They So Hard to Count?

A major study finds no link between pot and car accidents.



Pot prohibitionists commonly warn that legalizing marijuana will result in more traffic fatalities as the number of stoned drivers on the highways multiplies. But as I explain in my latest Forbes column, documenting marijuana's role in car crashes is a lot harder than the prohibitionists seem to think. Here is how the column starts:

Last year, during a congressional hearing on the threat posed by stoned drivers, a representative of the National Highway Traffic Safety Administration (NHTSA) was asked how many crash fatalities are caused by marijuana each year. "That's difficult to say," replied Jeff Michael, NHTSA's associate administrator for research and program development. "We don't have a precise estimate." The most he was willing to affirm was that the number is "probably not" zero.

Michael knows something that grandstanding politicians and anti-pot activists either do not understand or refuse to acknowledge: Although experiments show that marijuana impairs driving ability, the effects are not nearly as dramatic as those seen with alcohol, and measuring the real-world consequences has proven very difficult, as demonstrated by a landmark study that NHTSA released last Friday. In "the first large-scale [crash risk] study in the United States to include drugs other than alcohol," NHTSA found that, once the data were adjusted for confounding variables, cannabis consumption was not associated with an increased probability of getting into an accident.

Some news outlets accurately reported that result, and some did not, apparently because some reporters actually read the study, while others were content to skim NHTSA's press release. Such carelessness misleads policy makers who are grappling with the issue of how to determine when people are too stoned to drive. It also aids pot prohibitionists, who cite the prospect of more blood on the highways as an important reason to resist legalization.

Read the whole thing.

NEXT: The Measles Outbreak and the Precautionary Principle

Editor's Note: We invite comments and request that they be civil and on-topic. We do not moderate or assume any responsibility for comments, which are owned by the readers who post them. Comments do not represent the views of or Reason Foundation. We reserve the right to delete any comment for any reason at any time. Report abuses.

  1. Look, Sullum, we KNOW it causes a lot of crashes. Eventually we’ll find the numbers to prove it. That’s how science works.

    1. ^^THIS


    2. Yep. It’s science.

    3. And that fact that it’s that hard to prove shows how insidious the danger is and that we have to be that much more careful to prevent it. [/actual statist argument]

    4. Yeah, you can’t fight religion with data. You’re speaking different languages.

    5. There’s a consensus among every scientist ONDCP paid to say there was a consensus!

    6. Someone is obviously in the pocket of Big Weed.

  2. The most he was willing to affirm was that the number is “probably not” zero.

    This is why NHTSA’s associate administrator for research and program development get paid the big bucks.

    1. Probably not zero bucks, that’s for sure.

    2. Regardless of the number, it’s reason enough to put people in a rape cage.

  3. How many people are driving around on meds like paxil and adavan and the like.Drugs that are far more dangerous.

    1. Paxil is an SSRI, probably has no noticeable effects at all, whereas pot clearly does. Ativan, definitely has noticeable effects, but I would say subjectively way less than pot as well. Not that any of that matters, but think it’s absurd to say those are more dangerous to drive on. Leave all of them alone.

      1. p[axil and drugs like it can have terrible side effects,too many to list.They can make you a danger to yourself and others and cause you to move to others drugs and alcohol.They and much worse than pot.

        1. SSRIs? Most of the time doctors ask patients to keep a diary of how the feel so they can check 6 weeks later to see if the drug is working or not because the effects are so subtle.

          1. The effects are subtle when the worse side effects aren’t in play. But for some people the effects can be pretty bad.

            One of the major side effects of most anti-depressants is suicidal thoughts. I’d much rather encounter a stoned driver than a suicidal one.

            1. Only in people under 25. In fact, for people over 25, suicides decrease.

              1. A lot of people under 25 drive.

                1. Yes. And pot can fuck you up. I’m just saying it’s goofy to say Paxil or Ativan are more dangerous than pot. There’s no evidence either way.

              2. Only in people under 25. In fact, for people over 25, suicides decrease.

                This is simply not true. For me (age 40+), any drug that has a warning about increasing suicidal thoughts does exactly that. Sleeping medications, anti depressants and some non narc pain/muscle relaxers send me into the black hole within a week.

                Living in Colorado and having a medical pot card I would be much safer on the road stoned than any of the above meds. I’m also on a lifetime supply of Oxy for medical problems. I would be safer stoned than on Oxy as well. Being stoned makes me want to sit and play bass or guitar rather than get out anyway.

                1. anecdotal evidence vs. clinical trials…

      2. If you’re beginning your SSRI regimen, the effects can be dramatic. It’s not uncommon to have extreme mood swings and other unpredictable behavior the first 1-2 months on an SSRI before your hormones stabilize. Weaning yourself off of one can be just as iffy. Some SSRIs have more side effects than others — Paxil, which my SO was on for a while, I heard is pretty bad for a solid 2 months.

        1. All of that can be said about pot too. Again, I’m talking in general. Most people who take SSRIs barely even notice they’re working, and the main side effects are things like weight gain and anxiety.

      3. Drivin while feeling the effects of cannabis, from personal experience as well, is far, far easier and safer than xanax, klonopin, etc.

  4. That will not stop them. They will just do what they do with alcohol; count every crash where either driver is under any influence of alcohol as “alcohol related”. If you have a glass of wine and a BAC of .05 and under the legal limit and driving some lunatic runs a red light and t-bones you, that crash will count as “alcohol related” in the statistics. Note they use the weasel word “related” not the meaningful word “caused”. They rely on people to assume “related” means caused when in fact it doesn’t.

    They will do the same thing here. Everyone time one is an accident and in any way tests positive for THC, the crash will be blamed on marijuana use regardless of the circumstances. Give them time and they will torture the facts to give the answer they want.

    1. Not only will it be “alcohol related,” but the guy who hit you will not get a ticket. That and the police report will make no mention of the fact that the guy who hit you ran a red light. The result will be you being forced to pay restitution to the guy who hit you.

      1. That’s where photo evidence, eyewitness accounts and a good lawyer come in handy. You can’t get the cop to do his job, but you can still defend yourself.

        1. If you can afford one. Not everyone has five grand sitting around for a DUI lawyer. Thing is, they’ll offer a plea that’s lower than DUI, but includes restitution. If you balk at the restitution, then you’re going to trial and will be found guilty because of your BAC. It’s a lose-lose situation.

          1. How can they give you a DUI if you’re under the legal limit, as in John’s example?

            1. The legal limit is only used as one piece of evidence for or against a DUI/DWI/OVI. They can use other evidence as well, ie. swerving, field sobriety test, etc.

            2. In Ohio,you can be arrested for dui no matter your bac,it’s up to the cop

            3. They routinely charge you DUI if you’ve got even the slightest amount of alcohol on your breath. That way if you don’t accept a plea bargain (Reckless Driving and fixing the car that hit you for example), you risk being convicted of DWAI in court. You might be able to get out the restitution, but you’ll still have DWAI instead of say Reckless Driving on your record. Either way you lose. Unless you give ten grand to a lawyer who is friends with the DA. Then you might get the whole thing dropped.

    2. That’s why DUI stats are bullshit.BTH,most DUI deaths occur at bac of ,15 and higher,and,most deaths are the drunk driver .

    3. That’s why DUI stats are bullshit.BTH,most DUI deaths occur at bac of ,15 and higher,and,most deaths are the drunk driver .

    4. The only upside is that it is a lot harder to test for THC than for alcohol. They could start forcing a whole lot more people to have blood tests. But without some equivalent of a breathalyser, I don’t think it will be as widespread. Maybe I am too optimistic.

      Hopefully people will start to figure out that disaster is not going to follow legalization and forget about all of this crap.

  5. If Marijuana Causes Lots of Crashes, Why Are They So Hard to Count?

    Because pot messes with your short-term memory, DUH!

    1. Damn, so I just forgot about all the havoc I wreaked on the roads? Dude.

    2. I was gonna count the accidents until I got high
      I gonna get up and find the stats but then I got high
      My data is still messed up and I know why
      ‘Cause I got high

  6. Looking at the study, I would say it’s irresponsible to use this study to try to prove either side of the argument. It basically says nothing interesting.

  7. The New Republic’s resident liberation theologist blames Richard Dawkins for the Chapel Hill Shooting.

    I especially love this part:

    “For Richard Dawkins, the fact that Islam is inherently violent is as obvious as the fact that everyone should believe as much. More telling yet are his other prejudices, expressed with equal certitude and impatience: that western feminists have no legitimate problems compared to women in Muslim majority countries; that good pornography would set theocracies aright, had we the magnanimity to bestow it upon them.”

    So Richard Dawkins accurately states that Western feminists are immensely privileged compared to the oppressed women of Saudi Arabia and jokingly points out the sexual repression of fundamentalist Islam.

    That monster.

    1. Did the author invite logic into her red room of pain to torture it that much?

    2. That would be annoying but not utterly evil and offensive if this guy were willing to blame the murders in France on radical Muslim clerics. You know however he would never do that. So not only is this a case of unfairly blaming Dawkins for the actions of a psychotic, it is even worse because it is also a case of anti-Western bigotry and using political correctness to excuse evil.

      1. This is hilarious:

        “Perhaps this will be a moment of reflection for the New Atheist movement and its adherents. If nothing else, the takeaway should be that no form of reasoning, however obvious to a particular cohort, has a monopoly on righteousness. And no ideology, supernatural or not, has a monopoly on evil.”

        Except that this appears to have been a parking dispute. A religious person cutting your head off for opposing their religion is caused by that religion. An atheist shooting someone over a bizarre parking lot argument is not caused by atheism.

        1. At the same time, it’s kind of fun to see non-religious (read non Christian) groups being erroneously, generally maligned for the actions of one person marginally affiliated with them.

          1. What ever floats your boat, I guess. I think it is just shitty and irritating when anyone does that. Collectivist bullshit is collectivist bullshit.

            1. I agree completely. It’s pure schadenfreude, and admittedly childish.

          2. I totally get the schadenfreude. Dawkins has made a career doing to religious people the kind of bullshit this woman is doing to him. It is still wrong and this woman should be called out for it. Dawkins, however, is certainly not a sympathetic victim.

        2. Even if the guy had been Dawkins’ biggest fan boy and had decided to murder Muslims to further the cause, that still wouldn’t have anything to do with Dawkins.

          Dawkins advocates some very nasty and tyrannical shit. He has never to my knowledge however advocated the murder of religious people, at least not directly. Dawkins is no more responsible for the actions of this psychotic as you or I are.

          All this bitch is doing is using a tragedy as a cheap excuse to shut people she doesn’t like up.

        3. How about a little reflection on all the awesome stuff her commie buddies did in the 20th century?

          1. Her commie buddies?

            Care to reflect a little yourself?

            I’m up for a debate.

        4. Her twitter feed is hilarious.

          Elizabeth S. Bruenig @ebruenig ? 16h 16 hours ago
          Woah Christian Grey is a capitalist pig, why are we talking about him holding down girls in bed when bro is holding down an entire class?

    3. It’s sad that a girl that pretty is also brain damaged. I hope her family finds the strength to pull the plug once it comes time to let her go.

      1. She is cute in an uptight sorority girl from Dartmouth kind of way. She is not unattractive. She is, however, in no way attractive enough to make up for her lack of IQ and personality.

        1. Or for the fact that her crazed, fundamentalist religious beliefs would make her the least interesting person alive.

          She’s also a Communist who argued that all money above that which is needed to live is the property of the government and therefore should be forcefully confiscated.

          She’s very, very evil.

          1. She’s not a “communist”, she’s a “distributist“.

            1. Oh, well that is just so much different then.

        2. I’d do her in a NY minute. Perfect cocksucking lips.

          And, if she were sucking my cock, she wouldn’t be able to talk about her beliefs, which are…offputting…

          1. Sure. Sadly, you would probably have to talk to her to get to that point. And I wouldn’t kick her out of bed. I just can’t imagine putting in the effort necessary to get her there.

        3. She looks like she is about 14.

        4. I would submit she may be smarter than you.

          But we would need to debate that.
          You up for a debate?

          Do you call the GOP/Tea “fiscal conservative”

          Do they pay for anything?
          do you pay for your spending

    4. Miss Elizabeth Stoker Bruenig is quickly crossing the line from noisome to evil.

    5. I thought the Chapel Hill shooting was over a long-term parking dispute. Is that not the case?

      1. It will be now that we know he’s an atheist. If it were a Tea Partier, Christian, Pro-lifer, etc. It would be related to the entire movement and used as propaganda for the next 50 years. This will disappear in a week or less.

    6. Here’s a post from her husband? brother? male alter-ego? which the author expresses his rage against the fact that there are different schools of libertarianism.

      The fact that he gets lost in the weeds about culture war bullshit and can’t see the commonality behind all the different schools is very telling as to his inability to think deeply. And he had the chutzpah to tag his post with the label “philosophy”.

      1. Wow, an article with a headline that starts with a hashtag…

      2. Its her husband and they’re two of the worst people currently working in ‘journalism.’

        Matt Bruenig claimed that the Ferguson riots could have positive economic effects. A sea of broken windows!

        1. Look at how WWII helped Japan and Germany. We should have at least one World War every year.

      3. Mulatto,

        That article shows how stupid these people are. They are just shallow thinkers who have a very hard time seeing abstract concepts and thinking systematically. That guy thinks very crudely and mostly in very simple concepts. He just isn’t sophisticated enough to see common assumptions in differing arguments.

        The inability to grasp analogy or see common assumptions behind different arguments seems to be common among the Left. The biggest thing the leftists and left leaning who post on this board seem not to understand is how two different arguments can share common assumptions even though they make radically different points. If you tell one of them “sure but that argument is no different than saying this”, it goes right over their heads. They cannot grasp that just because the conclusions are different the arguments can still proceed using the same or similar assumptions and logic.

  8. its very simple pot smokers also drink alcohol, there is no test for pot but there is for alcohol so all those high on pot are falling under the alcohol label.

    1. Many people who smoke pot do not drink alcohol, and there is indeed a blood test that can measure active THC in the blood. In short – you don’t know what you’re talking about.

      1. I’m assuming he was full of snark… not the other s-word.

      2. For someone named sarcasmic…

        1. SMOKE!

          *sparks up bong*

  9. “NHTSA found that, once the data were adjusted for confounding variables, cannabis consumption was not associated with an increased probability of getting into an accident.”

    Yeah, but still…

    /Team BERULED

  10. From the table, it’s obvious that we must force everyone onto antidepressants and/or stimulants. For safety.

    1. I find your ideas intriguing, and would like to invite you to be my Surgeon General should I be elected President in 2016…

      Almanian for President – 2016
      I Probably Won’t Make It Any Worse

  11. I’d much rather share the road with a pothead than a drunk. Worst thing the pothead might do is drive under the speed limit before turning around to go back to a missed turn.

    1. He’d probably leave his turn signal on for the entire trip and he might be slow to start at green lights, too. Insufficient acceleration.

      1. You just described very elderly drivers too…wait a minute…


        1. Elderly people driving, on weed or not, is far more of a hazard than drugged or drunk driving.

          1. Nice theory, but the actuarial tables don’t support it. The most hazardous drivers are teenaged males, followed by teenaged females.

            Older people learn to compensate for their disabilities. Young kids can’t compensate for their lack of judgment.

    2. A drunk driver will run a red light. A stoned driver will pull up to a stop sign and wait for it to turn green.

      1. Easily solved with a friendly honk.

      2. Yeah, more likely too just drive slower if anything.

    3. For most people, I think pot messes up your coordination less than alcohol (dose dependent, of course).
      But I’d say the biggest factor is that when drunk, people usually think they are driving better than they are and when stoned they think they are worse than they are.

  12. Car and Driver covered this like 30 years ago. The more you drink, the worse you drive. OTOH, some folks went through their course faster while on pot, i.e. they could focus more intently on the task on a short term basis. But then their mind would wonder and they would space when to exit the track into the pit area.

    1. Yeah, alcohol isn’t too much of a problem is you’re aware of being impaired and compensate for that. Including by compensating by getting out of the car and waiting to sober up a bit.

  13. Caden. I just agree… Patrick`s st0rry is astonishing, last tuesday I got a top of the range Land Rover Defender sincee geting a check for $6814 this last 4 weeks and in excess of 10k last month. it’s certainly the coolest job Ive had. I actually started……………


  14. Prohibitionists are monsters. Behind the caring protector facade lies a sadist. Read full article at my website.

    1. What is your website?

      1. Clicked your name and got it.

  15. where does Reason stand on Industrial Hemp as Schedule 1?

Please to post comments

Comments are closed.