By on May 11, 2016

Marijuana weed pot joint

Impairment tests used by authorities in U.S. states where marijuana use is legal in some form have no basis in science, and their results essentially mean nothing, a recent study concludes.

Commissioned by the American Automobile Association’s safety foundation, the study found that no blood test for THC, the active ingredient in marijuana, can accurately determine a driver’s level of impairment, the Associated Press reports.

The finding blows law enforcement’s main method of convicting high drivers into the weeds.

In five of the six states that recently legalized marijuana, a motorist is deemed guilty of impaired driving if their blood level of THC passes a certain threshold.

Because impairment levels are highly variable and depend on the individual, rather than blood THC levels, the tests lead to some motorists being wrongfully charged, with others going free, despite being high as a kite at the time of the test.

Regular users, be it stoners or medicinal users, often show lower levels of impairment than intermittent users. Their blood, however, often contains THC for longer periods than a once-in-a-while weed smoker. TCH tests that minic the blood alcohol tests administered to drunk drivers won’t recognize these distinctions.

AAA wants the tests scrapped and replaced with an observation-based system, where trained officers analyze a number of physiological and behavioral indicators to determine a person’s level of impairment.

“There is understandably a strong desire by both lawmakers and the public to create legal limits for marijuana impairment in the same manner we do alcohol,” said Marshall Doney, AAA’s president and CEO. “In the case of marijuana, this approach is flawed and not supported by scientific research.”

The six states that use the blood test — Ohio, Nevada, Washington, Colorado, Montana and Pennsylvania — could be joined by more states this fall. Their ranks could double, in fact, as lawmakers seek a way of detecting high drivers.

The study is a buzzkill for law enforcement members and state-level bureaucrats, but if the sole purpose of the THC blood test is to make roads safer from impaired drivers, its findings beg for acknowledgment.

North of the border, Cannabis — erm, Canada — plans to legalize marijuana use in the near future. The study will be of interest to their authorities, too.

A New York University professor quoted by the Associated Press said there’s a number of marijuana-related laws in need of fixing. Mark A. R. Kleiman, who specializes in drug and criminal policy, said several states have laws against motorists having any THC in their bloodstream, despite the fact that trace amounts can linger weeks after the individual became sober as a judge.

A noisy child in the backseat of a vehicle is as big a risk factor as using marijuana, Kleiman said.

[Image: Check Grimmett/Flickr (CC BY-SA 2.0)]

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51 Comments on “Reefer Madness: ‘Driving While High’ Laws Aren’t Based on Science, Says Study...”

  • avatar

    I submit people getting high behind the wheel aren’t a problem.

    Amirite, Social Media butterflies updating your posts at 75 MPH?

    • 0 avatar

      The two are not mutually exclusive.

    • 0 avatar

      I don’t need any potheads driving around – as well as I don’t need social media users or phone chatty chat chatters…

      • 0 avatar

        Potheads vs. A$$Holes on edge and late for everything soccermoms on meds? You wanna rethink that? Potheads just cruise, with zero twitterfacing.

        • 0 avatar

          Regardless how you feel about drugs in general, I invested in companies making marijuana breathalyzers (like BLOZF).

          The law will NEVER allow intoxicated driving.

          Might as well turn oppression into a few bucks right?

          • 0 avatar
            Mr. Orange

            Spoken like a true American. Why let a bad opportunity go to waste.

          • 0 avatar

            While probably even more dangerous, what about “driving while blowhard”? “Here sir, blow hard into this Blowhard Detector…”

            Product investment is a different topic, maybe start a new thread. Good luck with that, but stoned driving is better than any other form of “intoxicated driving”.

            And even 100% sober drivers are hardly ever, never dangerous to themselves and others. Probably more so than stoned drivers.

            The “law” is just picking the lowest hanging fruit. Except with pot being so readily available, there’s much less alcohol related DUI revenue, so they’re scrambling for cash flow

          • 0 avatar

            “While probably even more dangerous, what about “driving while blowhard”? “Here sir, blow hard into this Blowhard Detector…””

            That made my afternoon.

          • 0 avatar


            I bought BLOZF at less than 0.01

            Take a look at me now.


            There’s ALWAYS money in oppression.

            I invested in TASER too.

            If you guys are smart, you’ll listen to my stock advice so you can profit.

            Faraday is gonna be huge.

            NOBODY listened to me when Tesla was less than $30 a share. I told ya – BUY BUY BUY.

            I bought, bought, bought.

            Now I’m rolling HELLCATS.

          • 0 avatar

            “….Now I’m rolling HELLCATS.”

            The Prosecution rests its case, Your Honor.

          • 0 avatar

            @BTSR: Red light cameras and speed cameras

          • 0 avatar


            $150 ticket

            Atlantic & Essex

            41 in a 25mph.

            That’s not bad considering I’m usually doing over 60.

  • avatar

    As a medical user I can report that it generally improves every aspect of driving (and wrenching on) my crappy ’98 Corolla.

    I also find myself increasingly tolerant of others on the road. The asshole driving five under with his blinker on in the fast lane is less likely to hear about his infractions if I’ve committed one of my own.

    I’d never want to put myself in a track situation involving properly fast cars while stoned. For the drudgery of everyday traffic and slaloming between potholes? It’s a fucking necessity.

    • 0 avatar

      There are lots of drunks who also believe that they are better drivers while intoxicated. Wishful thinking is just awesome, isn’t it?

      • 0 avatar

        Well, I think the point is, it may not just be wishful thinking, as the studies show.

        Like alcohol, we need some good, solid repeatable tests that let us properly answer this question. Lets hope it doesn’t take as long as drunk driving did for us to figure out (or at least, with less fatalities).

        What’s interesting, though, is that it’s likely that these issues aren’t only related to THC. I mean, even OTC medications can affect your reaction time and alertness, after all.

        • 0 avatar


          Two points.

          First…this should have been resolved BEFORE the legalising of pot. Under this situation we now have the possible risk placed upon accident victims without the recourse to place blame on possibly inhibited drugged drivers.
          This rush to legalize before having all the testing and data in front to consider shows the stupidity and foolhardiness of mass social movements.

          Second..they are just now reporting the high increase in pot related accidents in the legalized states. I saw this on several news sites this past week, including CNN.

          see for yourselves:

          It amazes me the desire for humans to stuff normally easy to see common sense under the carpet when they feel the need to protect and prop up their own wants and wishes.

          No thinking person would possibly think smoking pot, especially today’s more potent varieties, does not inhibit driving skills and should not be allowed. If you do…you have not experienced the powerful pot we have today.
          Utter nonsense. Madness…refer madness, in reverse.

          • 0 avatar

            From the article you posted:

            “All this report really shows is that more people in Washington State are likely consuming cannabis, and thus might have some THC in their systems at the time of an accident. But since having THC in your system tells us nothing about your potential impairment, it would be like a report showing how many people involved in accidents had drunk a beer in the last week,” said Taylor West, deputy director of the group.”

            Or, as scientists are wont to say, “correlation is not causation”

          • 0 avatar


            Right on. You proved the point that having THC in your system doesnt mean youre currently impaired, and you totally stole his thunder in doing so (and rightfully so at that). People cant seem to get that through their heads. If I smoke on Friday night and no more thereafter, Ill test positive on Monday morning. Im not still high on Monday, but that doesnt mean it isnt going to show up. Its not like alchohol, damn it! You cant apply the same logic!

            Saying that there are more accidents involving people who have THC in their system IS NOT THE SAME as saying there are more accidents involving people who are high at the time of the accident. Likewise, its also not the same as saying the accidents were caused because the at-fault party was high. If I smoked weed a couple hours ago and Im sitting at a redlight when some bimbo looks up from her text too late and plows into me, it is not because I smoked that it happened, yet Im still adding to the one-sided “THC-involved accident” statistics.

            The other side would, what, have someone who smoked weed not drive for an entire month afterwards to make sure theyre not “intoxicated”? Stupid. It shows a complete lack of understanding.

            “Well I dont want to be out there with a bunch of stoned drivers!” Well, I dont want to be out there with some idiot driving his HELLCAT at 60 MPH in a 40 zone with impulse control issues, but I am forced to, arent I? You want to remove every potential problematic driver from the road? Fine. Everyone will be in autobot cars and this site can hang up its hat as driving by humans will end. Sounds like someone’s idea of hell to me.

            The point was also that weed affects different people in different ways. If you havent smoked in years (or ever), one clam bake session will have you ripped out of your mind, and hell no you shouldnt drive for at the very least, an hour (probably more, a lot more).

            A regular user who smoked at 9:00 is probably normal enough to safely drive at 9:15. Once the initial rush is over, their system is not going to be as affected as someone who’s tollerance is nill. They wont be lost in la-la land while mowing down school children left and right, their mental state is just as “normal” as anyone else.

            Cue the idiots who will say “well Im a regular drinker, so downing 5 shots before driving home is okay, right?” Because alchohol and weed are exactly the same…NOT.

          • 0 avatar

            “Under this situation we now have the possible risk placed upon accident victims without the recourse to place blame on possibly inhibited drugged drivers.”

            Why would this affect the determination of fault?

            If a person can drive fine while stoned, I’d rather share the road with him than with a sober driver who crashes into other vehicles. Attitude matters far more than motor skills when it comes to driving on public roads.

      • 0 avatar

        You can’t compare alcohol and marijuana, the effects aren’t the same. I’m not advocating for driving stone, but saying “we have to do something, even if it makes no sense”, well for once, let’s not do that.

      • 0 avatar

        Quite a few users of drugs, are safer behind the wheel when they’re on their meds, than off them.

      • 0 avatar

        I have a friend who is a MUCH better programmer drunk* than sober but that’s a different issue, altogether.

        * Up to 4 beers. After that it falls off precipitously.

  • avatar
    Land Ark

    What about America’s legal attitude toward marijuana is based on science?
    From outlawing it to give cause to arrest Mexican immigrants to protecting white women from crazed black men to keeping it illegal because of how much the US police forces need the revenue it generates – where’s the science?

    I’ve never smoked nor would I if it were legal but I can recognize when laws don’t make sense. And trying to make high driving and drunk driving the same is just more of the same.

    • 0 avatar

      Amen and kudos to AAA for taking this stance.
      Speaking of revenue, I’d be surprised if the paltry amounts local law enforcement brings in can hold a candle to the amount that state and federal governments could rake in if this were properly regulated. Aside from removing an unnecessary burden on the legal and prison systems, the sales tax and income tax (think of all those illegal growers & sellers out there) that could be reaped, make any income from traffic tickets not worth mentioning, I’m sure. On top of that, there will never be any significant scientific studies of the medical benefits of pot until the Feds decide it’s not to be classified the same as a drug like heroin or angel dust. Only then will Pharma companies devote the necessary resources to study the efficacy and safety (and methods of measuring impairment as a by-product) of pot and its derivatives. It’s not much different than booze or tobacco…regulate it, manage it well, profit from it and understand it. It’s the 21st century—no need to fear what we don’t understand.

      • 0 avatar

        It will still largely remain under the table and be made/sold illegally. Why would someone currently running a grow-op decide to pay taxes? That is the point everyone misses. There is a massive supply chain currently in place that pays not one dime to government. That will not disappear suddenly because it is legalized. There will be no windfall of revenue to governments as it will need to spend money to both try to shut down the illegal supply chain and deal with the consequences of greater consumption.

        • 0 avatar

          Illegal growers tend to vote against legalizing it, but the plus side is their income becomes legit, freely spent. Denver collects about 29% on pot sales, so you do the math. Yeah and yes.

        • 0 avatar

          Sorry Red, but that is not how it is playing out in the real world in WA. Even with the high taxes the price has been driven down from what it had been and the consumers seem to prefer being able to go to their choice of store and have a wide selection. Certainly it still exists but it was quickly decimated and will continue to dwindle until it disappears.

          Fact is that many companies were formed to grow, package, and sell it legally and while you can be sure that many of the former outlaws would probably still prefer the high profits they once had the vast majority of consumers has gone elsewhere.

          As mentioned below WA expects $156 million in revenue this fiscal year. They don’t need to spend big money to shut down the black market since market forces are taking care of that and fact is they weren’t able to do it in the past so what makes you think they would even think about trying up their efforts to locate illegal grows and sales?

        • 0 avatar

          People can also grow their own tobacco and brew their own beer, but the majority choose to buy it at a store instead.

          The same applies to anything that can be grown or produced by the individual. Some may take that route, but the majority still buy their tomatoes and apples rather than try to produce their own.

          The underground will not stop because its legal, I give you that, but as it becomes more common place and available, it will diminish in time to a slow trickle of what it is now. If you’re a respectable professional driving a late model BMW and living in an upscale neighborhood, are you going to go buy some weed from some shady character in a trashy trailer park or on the corner of Bad St and Worse Ave in the $h¡ГГ¥ part of town? Or, go to a nice, secure, upscale dispensary with a polite and knowledgable staff and plenty of choices depending on the desired effect you seek?

      • 0 avatar

        In the state of WA which has a high tax rate the gov’t is expecting about $156 million in tax revenue. We don’t have an income tax just a B&O which for most industries is pretty low.

        The federal gov’t will of course get a boost in their income tax collections since they still want and take that money even if they continue to keep it illegal on their books.

        Legalization is a win-win situation. The black market has almost completely been shut down though occasionally you still hear a story about an unlicensed operation being busted. However for the most part it has gone away as evidenced by the number of ex grow houses I’ve seen come on the market.

        I do believe that as long as we don’t get Hillary we will see the federal gov’t legalize and start taxing it sooner rather than later. The results in WA and CO make a convincing argument for all sides.

        It is well on the way to killing the black market in my state because competition has driven the price down while increasing the variety available to the consumer.

        In the old days you knew a guy or two and depending on his :business model” you had to “schedule” an appt with him at the 7-11 parking lot. You took what he had and its potency and quality was all over the place, you also payed top dollar even if it was crap.

        Now you walk into a store next to the 7-11 and get a large selection with the content analysis right on the label, at least in my state. The price also varies based on the quality/potency of the product. We have even seen price wars in some areas. My daughter has went off to college and as one might expect in a college town in a legalization state there are a lot of stores. One near the school had a big sign out front “home of the $10 gram” At another part of town a store had a sign out front touting $9 grams. A new one just opened on her way to school that was initially offering $6 grams. I’ve also seen ads in the school newspaper with $5 off coupons.

        So faced with those choices consumers have largely made the switch to buying legal.

        Another huge benefit that never gets mentioned is one of the benefits of the ending of the black market. That is that it is now grown in warehouses/green houses in industrial or agriculturally zone land. Before it was grown in the house next door or down the street. Very few people really understand just how common useage was and how possible it was to have a grow house in their neighborhood. In that college town I decided to buy a place for my Daughter and room mate. I looked at many houses during the hunt to find something that met my investment criteria and still nice enough and that my daughter liked enough to be “the one”. The number of houses that have evidence of being grow houses was pretty high. They ranged from really crappy places in the poorer neighborhoods to nice homes in solid median or slightly higher priced neighborhoods. The obviousness ranged from some equipment or room “enhancements” still in place to most evidence being removed except for a few lingering things that you have to look a little deeper.

        Interestingly in the most recent find of a former grown house the neighbor came over and was asking if I was buying ect, and I told him maybe but there are a few issues that concern me. He responded that he knew the “previous tenant had made some modifications to the wiring…for his…um…business”.

  • avatar

    …but if the sole purpose of the THC blood test is to keep funds flowing from the test manufacturer into lawmakers’ pockets….


    • 0 avatar

      While I don’t necessarily agree with you on the “sole purpose” part, there is something to the fact that drunk driving is a huge business for so many parties.

  • avatar

    Went full Business Insider level corny on this one, eh?

  • avatar

    [begin Robert DeNiro voice] Are you a pothead Willems? [end Robert DeNiro voice]

  • avatar

    I remember way back when – ’70s or ’80s – Pat Bedard of Car & Driver performed a test on driving high. Someone should try to find that article.

    • 0 avatar

      Pot is performance enhancing, so the driver can be faster through the cones or around the track. You have to take the right strain, but pot’s banned from sports for a reason.

  • avatar

    Could this be the reason millennials are ditching the idea of early age car ownership?

  • avatar

    What a load of crap .
    You can *instantly* tell the stoners by their replies .
    I’ve ridden with potheads many times back when and they’re *NOT* safer , not one bit .
    Impaired is impaired .

  • avatar

    I’m curious about but not competent to opine on this subject.

    The gentle weed of yore has been so tweaked and weaponized that I can’t imagine it bears any resemblance to what I drove around on in the ’70s & early ’80s.

    I haz a sadness for the passing of that brain-stimulating pot of me yoof.

    • 0 avatar

      It’s safer than driving sober in some ways, in others not so much, *except* you’re hyper aware of your impairment, and will compensated for it. Perhaps not doing anything but ‘driving’.

      Except the “other” type of pot, sativa, heightens your over all awareness, energizes you and could make you an overall better driver, than straight sober.

      • 0 avatar

        So are you contrasting indica with sativa? The little I’ve just read seems to indicate that indica generally gives a heavier, body-oriented effect versus the more cerebral sativa.

        Pretty sure everything I ever smoked back then was some variant of sativa. Thai weed, presumably indica, and other strains from that region were just appearing in the Midwest when I decided it would be better to enjoy things straight.

        Weed was an excellent experience for me; it and courses I was taking at the time triggered what became lifelong interests in history and languages. Sativa sustained mental effort and facilitated associative thinking. But I’m not sorry to have exited that scene before experiencing the types of hammer-weed to which indica apparently better lends itself.

        • 0 avatar

          Indica is what lends itself to “dope”, and the loser, couch potato with hardcore muchies and of course “Jeff Spicoli”.

          Sativa is the “other” lesser known, or downplayed strain by the media by and large. Some prefer “hybrids” combining both. Then there’s edibles/brownies/candy/etc.

          The Mexican varieties are more like what you remember as a kid. I don’t advocate driving while stoned, don’t get me wrong. But if you do it again, start small and ask someone. The information you want is everywhere.

      • 0 avatar

        This is total nonsense.

        In fact, this kind of, or lack of, logic and reason makes me understand the problems we have as a species even trying to carry on simple conversations.

        And I know.

        I was a main subject in many Los Angeles drug medical studies in the 70’s. I KNOW how we performed. I spent those long days under observation going through the tests under the influence of many drugs and combinations of these drugs. In cars and doing many other mental and motor skill testing.

        You are seriously bad wrong.

        • 0 avatar

          “Drug” studies by the Feds have predetermined outcomes. Did you decide what type of pot to take and how much? Did you try it by itself, know its purity and not laced with an opiate or something else? Sounds like a bunch of crap to continue the needless prohibition of pot. Millions of users can’t be wrong. You no doubt have friends and family that use pot regularly but wont tell you.

          It’s total nonsense propaganda sponsored by the US gov, pharmaceuticals, private prisons and other industries with deep, deep pockets, including the mob and various drug cartels. Why would the Feds want to end the gravy train???

  • avatar

    A large number of comments here are basing their opinions on the assumption that being stoned impairs driving.
    Reassess that basic assumption. It at necessarily so.
    I have said this on this website before as well as other ones. Until the mid 80s I (gave it up) used to, and I still do currently know plenty of people who duck into the trees while skiing, they get good and baked, and go right out and the ski bumps with no problems. Driving a car is literally child’s play in comparison. The sensory motor coordination and judgmental complexity of skiing bumps is far far more demanding. It only takes a lapse of less than a second’s time in any one of the aforementioned two skills to result in loss of control and a likely fall.
    Hell, I bet I logged nearly 100,000 miles driving while smoking cannabis back in the day. It was especially helpful in the boring to tears 55mph era to pass the time and make driving the Interstates at that stupidly low speed more entertaining.

  • avatar

    Here’s a thought: Let’s look at actual accidents and prosecute the people who caused those accidents. Crashed cars are crashed if the person who ran the red light was putting on make up or sniffing glue. People crushed while drinking coffee at a sidewalk cafe are dead whether the driver that left the road was senile or just tried tequila for the first time. I’ve seen people walk away from causing horrible damage because they were found not to be drunk. Most accidents are caused by people who aren’t drunk. Why does being sober take away responsibility for one’s actions? Drinking and driving is making a bad decision. So is almost anything else that results in accidental harm to another. DUI is an industry. Limits are now lower than make any sense for the majority of the population. Punishments are higher in some places for driving while not actually impaired than they are for causing a death with your car while merely incompetent. It is absurd.

    • 0 avatar

      No. We should not wait until people are killed before we get drunk drivers off the road.

      • 0 avatar

        I’m in favor of actual tests of impairment as discussed in this report. Just as some people go through life stoned without causing car accidents, I know alcoholics who spend years with high tolerances before their liver function falters. They are no more dangerous than the majority of drivers.

        I took a first-time-offender class following a speeding ticket when I was in high school. The police officer teaching the class gleefully told the story of pulling someone over for a burned out license plate bulb and then smelling alcohol on them. He said the person was driving fine and his speech wasn’t slurred. The driver passed all of the field sobriety tests and his eyeballs didn’t ratchet while following a pen from side to side. Because of the smell of alcohol, he administered a breathalyzer test anyway. The man blew something over a .20 bac. He was not impaired, merely a high functioning alcoholic. The police officer seemed proud of catching the guy, but the story was far more educational than he meant it to be.

        You only ever accumulate knowledge via repeated conditioning through consistent messaging. You’ll never learn from experience, as you’re simply not observant or intelligent enough to do so. You’re a propagandist’s wet dream, and so you’ll never question whether ruining someone’s life for having trace amounts of alcohol in their system while driving to work the morning after a birthday celebration incident-free is a good thing or not. You don’t make the world a better place by your presence.

        • 0 avatar

          “You only ever accumulate knowledge via repeated conditioning through consistent messaging. You’ll never learn from experience, as you’re simply not observant or intelligent enough to do so. You’re a propagandist’s wet dream, and so you’ll never question whether ruining someone’s life for having trace amounts of alcohol in their system while driving to work the morning after a birthday celebration incident-free is a good thing or not. You don’t make the world a better place by your presence.”

          Wow, are you available for parties?

    • 0 avatar

      The general population prefers having their lives dictated by issues of morality. This is more pleasant to them than the idea of being held responsible for the consequences of their decisions. That way, when they harm someone through negligent behavior, it was just a mistake that the higher powers will forgive, since they were behaving morally.

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