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Taking Drugged Driving Seriously: What Does the Science Say?

September 21, 2017

I’ve been reporting on cannabis full-time for more than 15 years, so I like to think I’ve heard it all—pro and con—when it comes to the legalization debate. In all that time spent weighing facts and debunking disinformation, only one con argument has ever given me serious pause: What if a large number of newbie pot smokers suddenly get behind the wheel and all start riding dirty at once? 

There are many other supposed cannabis dangers that would warrant being taken seriously, if a small bit of independent investigation didn’t reveal them to be overblown or baseless.

For instance, science shows definitively that cannabis is not a gateway to harder drugs, is not addictive relative to other drugs (including caffeine), does not cause cancer or harm the lungs, and does not lead to an increase in violent crime.

Not that cannabis is completely harmless, of course. But if smoking herb turned you into a scatterbrained, violent heroin addict with lung cancer, that would be a serious concern. As hard data makes plain, however, it’s just not what happens.

Is “stoned driving” any different?


Will California’s New Drugged Driving Device Finally Get It Right?

Hot Button Issue

With Attorney General Jeff Sessions actively looking for excuses to crack down on legal cannabis, prohibition defenders are touting drugged driving as a reason to shut down the legal states.

Recently, the Denver Post published a major investigation of cannabis and driving. The story relied largely on data coming out of Colorado and Washington in the five years since those two states became the first to legalize the adult use of cannabis.

The series began with this headline: Traffic Fatalities Linked to Marijuana Are Up Sharply in Colorado. Is Legalization To Blame?

Well, Is Legalization to Blame?

Apparently nobody’s sure, because a smaller line directly below the headline stated: “Authorities say the numbers cannot be definitively linked to legalized pot.”

Authorities say the crash data can't be definitively linked to legalized cannabis.

In my experience, the authorities have never been shy about blaming a myriad of social ills on cannabis. So why the hesitance this time? And what, exactly, does the Denver Post mean when they describe traffic fatalities “linked to” marijuana? That’s an awfully vague term.

The Rocky Mountain High Intensity Drug Task Force—a federally funded law enforcement organization dedicated to suppressing illegal drugs—stated in a 2015 report that the term “marijuana-related” does not “necessarily prove that marijuana was the cause of the incident,” and applies “any time marijuana shows up in the toxicology report [of drivers]. It could be marijuana only or marijuana with other drugs and/or alcohol.”

Which means that if a drug test shows you smoked half a joint last week and drank a bottle of vodka twenty minutes ago, your car crash goes down in the books as “marijuana related.”


Marijuana Goggles and ‘Stoned Babies’: Why AAA Is Propping Up Prohibition

Deal With Facts, Not Fear

Before we fully delve into the confusing science of stoned driving, let’s start by stating the obvious. Operating a motored vehicle while dangerously impaired on any substance—whether legal or illegal—is rightfully a criminal act.

Compared to sober drivers, THC-impaired drivers have a 5% greater risk of crashing. Alcohol-impaired drivers under the legal limit (.08) have a 225% greater risk.

So when the Post asked if “legalization” was to blame for traffic fatalities, that was a skewed way of framing the question. Nobody would argue that alcohol legalization is responsible for a drunk driving accident. We rightly blame the drunk driver, both in the court of law and the court of public opinion.

Clearly, cannabis use can lead to driver impairment, which increases accident risk—but how much cannabis? And how much risk? That depends on a lot of factors.

While it’s literally impossible to fatally overdose on infused chocolates (unless you’re allergic to chocolate), you could fall asleep or space out at the wheel after eating them and cause a fatal accident. That’s a danger that imperils not just the driver, but anyone else in the car or on the road.

When Colorado legalized adult-use cannabis in 2012, it also included a per-se limit for drivers. State law specifies that “drivers with five nanograms of active tetrahydrocannabinol (THC) in their whole blood can be prosecuted for driving under the influence (DUI)… and no matter the level of THC, law enforcement officers base arrests on observed impairment.”


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Look at the Full Data Set

Putting aside for a moment the notorious difficulty of measuring cannabis impairment through blood tests or officer observation, the Post’s analysis raised serious questions about cannabis use and drugged driving.

One of the key findings in the Post report was this startling statistic:

  • From 2013 to 2016, the number of drivers who tested positive for marijuana use jumped 145 percent — from 47 to 115.

That doesn’t sound good. But it’s a wholly misleading statistic. “Testing positive for marijuana” only means that cannabis metabolites remain in the driver’s blood, even though the driver may be completely sober. The body expunges alcohol within hours, but those non-impairing cannabis metabolites remain for days and even weeks. The test will register as metabolite-positive if the driver consumed cannabis anytime up to three weeks ago.

If Colorado officials conducted a similar test to find drivers who consumed alcohol within the past three weeks—if such a test existed—it would find 55% to 75% of the state adult population (the percentage range of people who consume alcohol at least once a month) register as alcohol-positive. But they’re no more “drunk” than a metabolite-positive driver is “stoned.”

In fact, the Post data is doubly misleading, because the statistics on cannabis metabolites actually predate 2013. Annual reports by the state’s Interagency Task Force on Drunk Driving published data on metabolite-positive drivers involved in fatal crashes during 2011 and 2012. Those numbers reveal 2013 not as a normal, pre-legalization baseline, but rather as a bit of an outlier–an unusually low year for metabolite-positive drivers in crashes.

What the full data set reveals is that the percentage of Colorado drivers who are involved in fatal crashes, and have consumed cannabis sometime in the past three weeks, pretty much mirrors the percentage of adults who consume cannabis in the population at large. Which is to say, around 12% to 13%. It was a little under 14% prior to legalization, it was a little over 14% after legalization. In between it fluctuated between 8% and 12%.

Colorado: Drivers in Fatal Crashes (click to enlarge)

Consider the Odds

While the Post report included pushback quotes from two representatives of prominent cannabis industry trade groups, they didn’t talk to anybody like Paul Armentano, Deputy Director of NORML. He’s a longtime expert on these matters, with the peer-reviewed papers to prove it.

Armentano argues—I believe convincingly—that “increased prevalence of THC detection in drivers tells us little about accident risk,” as it could simply be evidence of increased use among the general public, increased testing by law enforcement, or both.

For Armentano, there’s only one metric that really matters: Odds ratios.

“To determine what role, if any, a drug plays in motor vehicle accident culpability we need to looks at odds ratios, which estimate the probability of an event occurring (e.g., motor vehicle crash) over the probability that such an event does not occur,” he says. “Odds ratios greater than 1 indicate a positive relationship, with stronger relationships reflected by higher numbers.”

And guess what? Drivers who test positive for active THC—not merely inactive metabolites—do increase their risk of crashing. But that increased risk is small compared to alcohol—or compared to opioids, texting, phone use, or even the distracting company of two other passengers in the car. When Colorado saw an upsurge in traffic fatalities last year, this was the headline in the Denver PostCDOT Director Blames Surge in Colorado Roadway Fatalities on an ‘Epidemic of Distracted Driving.’ 

The largest domestic case-control study to assess drugs and accident risk—published in a 2015 research note by the National Highway Traffic Safety Administration (NHTSA), a federal agency—found that the odds ratios for THC-positive drivers and crashes, when adjusted for drivers’ age and gender, came out to 1.05. That means THC-positive drivers have a 5% greater crash risk than drivers with no drugs or alcohol in their system.

Context and Relative Risk

It’s worth taking a closer look at that 2015 NHTSA study, because federal officials put a lot of stock in it as “the first large-scale [case control crash risk] study in the United States to include drugs other than alcohol.” Data was collected from more than 3,000 crash-involved drivers and 6,000 control drivers (not involved in crashes) over a 20-month period in Virginia Beach, Virginia. The data was fresh and solid: Research teams responded to crashes 24 hours a day, 7 days a week. Drivers were considered THC-positive if they tested for active THC, not for non-impairing metabolites still in their blood days or weeks after consumption.

While THC-positive drivers were 5% more likely to be involved in a crash, the researchers found that drivers who’d taken an opioid painkiller had a 14% greater risk of crashing. Here’s a chart from that NHTSA study comparing THC (marijuana) with opioids (narcotic analgesics) and other drugs:


Source: “Drug and Alcohol Crash Risk,” Compton and Berning, NHTSA Traffic Safety Facts Research Note, Feb. 2015

Those levels of increased risk were tiny, however, compared to the risk involved with alcohol. Drivers within the legal range of blood alcohol level as registered by a breathalyzer (BrAC) were found to be 20% to 222% more likely to be involved in a crash. At .08 BrAC, the legal limit, the risk increased to 293%. At 0.15 BrAC, drivers were more than 12 times (+1118%) more likely to be involved in a crash than a sober person. Here’s a chart from that same study, calculating the increased risk of crashing at rising blood alcohol levels:

Source: “Drug and Alcohol Crash Risk,” Compton and Berning, NHTSA Traffic Safety Facts Research Note, Feb. 2015

By comparison, a driver who has taken penicillin is 25% more likely to be involved in a crash. Drivers carrying two or more passengers are 120% more likely to crash. Drivers using mobile phones to talk or text are 310% more likely to crash.

A separate NHSTA study (“Marijuana And Actual Driving Performance”) further conceded it’s “difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects … Drivers with high concentrations showed substantial [impairment], but also no impairment, or even some improvement.” In other words, cannabis affects different drivers in different ways, depending on a number of factors.


Blood Testing Drivers for THC is Nonsense, AAA Study Says

Favoring One Set of Data Over Another

Strangely, the Denver Post’s analysis relies heavily on data compiled by the NHSTA, yet they never mention these striking findings from the very same federal agency.

My own theory on that wide range of responses (from “substantial impairment” to “some improvement”): Cannabis affects inexperienced users very differently than seasoned consumers. A 2010 study published in the journal Psychopharmacology concluded that “heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance.” And a 2012 study in the Journal of Analytical Toxicology confirmed finding “minimal impairment in driving-related psychomotor tasks in chronic daily cannabis users.”

So while the correlation between blood alcohol concentration and impairment is relatively consistent for most people, it may be impossible to establish a THC test that can truly gauge impairment the way a breathalyzer can for booze. Though not for a lack of trying, which creates the danger of severely punishing drivers simply for being cannabis consumers, not for driving while impaired.

A New Form of Prohibition

Because if it becomes essentially illegal to drive to work the morning after smoking a joint, then it becomes essentially illegal to smoke a joint—at least for the vast majority of us who are far more addicted to our cars than we ever could be to cannabis.

Speaking of automobile addiction: What’s with those car-junkies over at AAA (a.k.a. “Triple A”) lobbying against legalization and pushing “grossly distorted” data . According to a Leafly report, “the organization’s newly embraced anti-legalization stance is a hard turn from AAA’s previous position—which is to say, no position at all.”

Maybe it’s time for all AAA members who care about this issue to contact them and demand they start telling the truth.

The (Positive) Substitution Effect

For instance, what about the idea—hidden in all the data we’ve examined so far—that increased cannabis use could actually be making our roads safer by serving as a substitute for more dangerous behavior.

Increased cannabis use could be making our roads safer by decreasing alcohol intake.

Meaning that while cannabis use in and of itself does increase crash risk, in a zero sum game where someone’s either drinking beer, popping pills or smoking weed, then cannabis is most certainly the safest of those risk factors. A dynamic that, writ large, can have a sizable positive effect.

For example, one 2011 study found that widespread use of legally accessible medical marijuana actually produces a major improvement in public safety because of a correlated reduction in drinking and driving, and an overall reduction in opioid use.

“Specifically, we find that traffic fatalities fall by nearly 9 percent after the legalization of medical marijuana,” concluded University of Colorado Professor Daniel Rees and Montana State University Assistant Professor D. Mark Anderson.


This Medical Cannabis Researcher Explains How Marijuana Can Combat the Opioid Epidemic

No, You Don’t Drive Better Stoned

So, to sum up—no, you definitely don’t drive better stoned, especially in high doses. And double-especially if you’re not used to being stoned, or to driving, or to both. Infrequent users of cannabis incur a higher risk of crashing based on the increased motor impairment that comes along with having less experience with THC and its effects.

Most experts recommend waiting at least three hours after your last inhale of cannabis before driving, and waiting far longer if you’ve eaten edibles, since they can sometimes take two hours before the onset of effects, which can then last six hours or longer. Also, please be aware that mixing alcohol and cannabis is more dangerous than using either alone. And don’t ever smoke in a moving vehicle, as it’s irresponsible and also the easiest way to get busted.

Oh, and if you happen to be a passenger in a car heading out for a long road trip, then I highly recommend getting really, really blazed before getting into the car, and then bumping some killer driving music once you hit the highway.

David Bienenstock's Bio Image

David Bienenstock

Veteran cannabis journalist David Bienenstock is the author of "How to Smoke Pot (Properly): A Highbrow Guide to Getting High" (2016 - Penguin/Random House), and the co-host and co-creator of the podcast "Great Moments in Weed History with Abdullah and Bean." Follow him on Twitter @pot_handbook.

View David Bienenstock's articles

  • lovingc

    The Drug and Alcohol Crash Risk report, produced by the Department of Transportation’s National Highway Traffic Safety Administration, found that while drunken driving dramatically increased the risk of getting into an accident, there was no evidence that using marijuana heightened that risk. In fact, after adjusting for age, gender, race and alcohol use, the report found that stoned drivers were no more likely to crash than drivers who were not intoxicated at all.

    • FLW

      > there was no evidence that using marijuana heightened that risk

      That’s what I thought I knew I read.

      But in this article, the author says the NHTSA determined they found a 5% greater risk. The article is so well written, I’m going to start repeating the 5% number to friends and family instead of the 0% number. Then I’ll have to explain the context, which includes things like the risk of getting into a crash is 35% higher in the 21st Century compared to the 20th, correcting for all other factors…

  • FlunkedAgain

    Dash Cams, buy one.

    The police have them in their cars, and they show the reason why someone would be suspected of driving below an acceptable level of competence.

    We aren’t really looking for impaired drivers, we’re looking for incompetent drivers.
    In theory, an “impaired” driver could be more competent than an “unimpaired” driver.

    Controlled testing on a road course measuring before and after competence needs to be done, and cold sober subjects need to be measured also.

  • Woody D

    I was a cop for almost 30 years and I am a cannabis user. My only concern about legalization was the lack of any real test for DUI before legal weed hit the streets. Both sides of the argument represented in this article are using circumstantial evidence to make their point. The fact is science and Law Enforcement are still trying to figure it out. For example, The San Diego Police Department is using mouth swabs to check for some marker that is only present within four hours of ingesting cannabis. To build a case you would need to see erratic driving, physical symptoms of being impaired and have a positive test result….in other words,.if it walks like a duck and talks like a duck it’s likely a duck. It will take a while to establish what effect legalization will have on traffic safety. The cannabis haters are going to say the sky is falling because of statistics that might indicate weed crazed drivers are causing accidents, while people like the author wax poetic about studies that potentially support their side as well as a myriad of other points that may or may not speak to the issue at hand. Bottom line, if you toke up don’t get behind the wheel for a few hours. If you mac out on that tasty edible, you might want to wait until the next morning to drive. Like the author said, YOU DON’T DRIVE BETTER STONED!

    • Lisa Gage

      Thank you so much for speaking up on this subject. I am a MADD mother and this is a subject of great concern here in California. I am so devastated not to be able to attend conference in Anaheim this weekend for just this reason. Some law enforcement are arresting and citing people and then asking questions later or trying to make the scienc stick while there still is no exact science to back up charges. I truly believe that the stoned driving and work related testing needs to be a major focus of attention to move this forward. Cannabis is still being compared to many very dangerous drugs that are in no way a comparison to each other. In my opinion it is ridiculous to expect those who are now not consuming opiates or even some cold and flu meds to be cited and or convicted of DUI or not be considered for the job because they had cannabis weeks or even hours before work. Another pet peeve is the delivery of this plant from one place to another is a whole nother can of worms!!!

      • FLW

        > Another pet peeve is the delivery of this plant from one place to another is a whole nother can of worms!!!

        You mean like in D.C., where Cannabis is legal, but you’re not allowed to buy or sell it? So it’s legal, but no one can get any, anyway? A government run sham; they don’t want to give up the power to arrest people willy-nilly.

        Instead, the government should consider Cannabis to have the same legal significance as forsythia or habañero peppers; an 18-wheeler full of weed should be considered a wealth of health, and the police can go after something associated with violence, instead.

    • Aaron

      Great response, however I want to rebut your very last sentence. For some people Marijuana is what is in fact enabling them to drive. For somebody who suffers from muscle spasms or neurodegenerative diseases such as parkinsons or grand mal seizures Marijuana way actually be PREVENTING a traffic accident.

      • Woody D

        The sad fact is, some folks just are not going to be able to drive due to medical conditions they have, in fact the DMV will suspend drivers licenses for some of the ailments you listed, both for the symptoms of the disease AND for the effects caused by the meds prescribed to fight the problem. Sure it is true a medication may suppress the symptom of the disease and allow the person to function in life, but many meds including cannabis also affect a person’s ability to operate a motor vehicle. This is precisely why pharmaceuticals often come with a label saying “do not operate a motor vehicle while taking this medication”. Driving is not a right, it is a privilege. Simply put, if you are a potential danger to the public behind the wheel you should not drive.

        • Dave Lahti

          Not one of my scripts say DO NOT drive or operate dangerous / heave equipment . Mine advise USE CAUTIONwhen drivivg or until you know how this medicine effects you. . Common scence I think

          • klw


        • Isaac Mizrahi

          thanks woody. retired nurse here. stoner for around half a century…drug crisis paramedic. top of my class in both. just to establish a baseline, so to speak…
          if you want to know what i was going to say, ask woody…. ; – ) nice job, w…and thanks for saving me the time…

        • klw

          Pharmaceuticals like cannabis differ and affect everyone differently. Lack of sleep while driving is much worse then cannabis and we have no laws about sleep. Most are warnings about operating machinery or a motor vehicle. Not a one size fits all answer.

          • Ryan_Dyne

            There shouldn’t be laws about sleep; the laws should be about driving impaired.

      • J_a_k_e

        Not to mention those of us with psychological profiles that benefit from added focus with cannabis

      • Grancy_Nace

        If you can’t drive safely without using marijuana, then you probably don’t have a driver’s license to begin with. I had a friend who had grand mal seizures, and he was unable to get a driver’s license.

        Weak argument, Aaron.

        • FLW

          Your friend with grand mal seizures — that’s one particular health condition.

        • klw

          So pain killers and muscle relaxers are OK?

          • guts knuckleson

            I use shitloads of vodka for pain control, am I OK to drive too?

          • MV 1967

            Stop drinking and driving! If i could I would turn you in.I hope you are not driving in my area.

          • guts knuckleson

            really obvious joke you half-wit

          • MV 1967

            Yes,I realized that after I posted…sarcasm, duh.

          • FLW

            No MMJ medical marijuana in your state? Everyone says THC is an excellent pain killer. Sorry the pain means you can’t take THC just for the recreation of it.

            Regulations in New York require a person to be dead for 6 months before they qualify for MMJ. So I’m just sitting and stewing before I die. 6 months later, I’ll be in like Flint.

            If I read correctly, when you stop using alcohol, the liver starts healing. You can speed that up by going through a couple of bottles of Milk Thistle Extract capsules.

            Lots of arguments in favor of switching to healthful Cannabis. You wouldn’t be the first to do so.

      • Suzanne Ledo

        That may be the case if you are using high CBD/low THC strains for seizures. But if you are using a strain that makes you high, you should not be driving, same as if you were taking narcotic pain pills.

        • MV 1967

          Not so. I have been driving high for 30 years.

          • klw

            Ya me too, about 45 yrs.

          • FLW

            From 1977 to 1987. Cannabis doesn’t anesthetize the brain. Just legalize it.

          • Lisa Gage

            We all have and never a dui ever asked even and now every time someone is pulled over there is that ?????

      • Majik53

        I represent that remark. I have nerve damage and have quirky spasms in my legs that cannabis controls very well. I do have to be medicated to drive safely, but not to the point of impairment. My tolerance levels are quite high, so I don’t feel the ‘high’ that others do. This is no exaggeration: I can puff a large bowl of a Sativa strain, topped with a spot of either hash or concentrate and I may feel some mild euphoria for about 10 minutes (but not always every time). After an hour, I am usually more than safe to drive or handle complex tasks.

        But that is me and how my unique body responds to the medication, and I have been a daily heavy user for more than a decade and a half to combat debilitating pain and random spasms. I would be more of a danger on the road unmedicated. I have had one traffic accident in 15 years, and it was from a distracted driver pulling out of a convenience store parking lot (and into me driving past it) last December.

        That said, we really need a more scientific test of impairment for the officials to use at the scene.

        • Majik53

          To clarify: A long time ago my doctor said I could either use pain pills for relief, OR use Cannabis. He wouldn’t approve both. I really should look him up and thank him. He would be pleasantly shocked to see me walking in balance without any ambulatory assistance. Most patients in my situation would be in a wheelchair, hopelessly addicted and suffering – and getting worse. So-called RSO saved my life.

          Not me. I was almost to the point of ordering a wheelchair in 2004 (8 months after my doc’s ultimatum) and discovered I was able to stand longer and sit longer without as much pain. I cancelled the order, and never looked back. I was even able to put my cane aside for months (after 2012) and only use it on my worst days (which are now few, thankfully), before I had to use it to just get out of bed and every step afterward until I went to bed again.

          If used responsibly, Cannabis is an extremely safe and effective medication that can be moderated to enable the patient to operate a vehicle in more comfort.

        • Brittney

          Ive heard, They are developing a breath test, like alcohol, to test how long the drug has been in your system.

      • Ryan_Dyne

        So, OK: change that to “don’t drive well enough (to be out there driving)”.

    • Sarah Hartzog

      Actually be open to the idea that some people may drive better stoned. Without more research we don’t really know! I wouldn’t drive high but if it allows someone to drive that has Parkinson’s, then that should be something that gets taken into account.

      • FLW

        I did the research. When I was a kid, I drove a couple of hundred thousand miles stoned on my parents’ insurance. I knew that if I ever got into an accident, that even if it wasn’t my fault, it would be considered my fault anyway, y’know, the way my eyes were so bloodshot I’m more likely E.T. than human. So I drove very carefully. (And yes, that included the occasional peel-out when conditions were right, even though I was driving with a stick shift in one hand, a Ham radio microphone in the other hand, a banana in the other other hand, a paper map in the other hand, etc…)

        30 years after my last joint, I’m still the most careful and defensive driver that I know. I’m one of the one-out-of-20 people on the road that doesn’t tailgate. 40 years after driving school, I still come to a full stop whenever I see an octagon, much to the amazement and occasional annoyance of people inside and outside my car.

        If a cop ever stops me, it’s going to be to give me one of those Gold Stars they hand out occasionally. [emoji of an angel, with the halo and everything]

      • Glen Folkard – GWS Survivor.

        Yes these people are insane here Sarah. You are right. In the right measure Sativa can make us acutely aware. People here are stuck in a paradigm and barely worth typing this much over. Drunken Judges of others lifestyles of peace. Drunken Pride.

    • FLW

      I think the article did a good job of gathering a pretty big list of evidence about how Cannabis can provide improvement in different circumstances, and is no hazard to society in other circumstances that we’ve been propagandized about ever since Reefer Madness.

      There’s a difference between “circumstantial evidence” and statistical probabilities. Circumstantial evidence pertains to a case-by-case. If statistical probabilities predict that different situations will affect the number of crashes with a high probability, please consider the meaning of “a high probability.” It’s not a departure from reality; instead, it’s about as real as it gets.

    • Glen Folkard – GWS Survivor.

      Its all in the dosage. There is no ONE “stoned” as you claim. Misinformation once more.

      • Woody D

        Misinformed….buddy I am a cannabis user and hardcore cannabis advocate as well as a highly trained and court recognized expert in DUI with 27 years experience dealing with the topic. I never claimed there is one stoned. Just like alcohol, there is a tipping point AND each person’s physical make up and tolerance levels will play a factor.

        First, the most common retort from a driver I put handcuffs on is “But I am not drunk!” DUI is about impairment. That is why simply having it in your system is not sufficient for a DUI arrest. Recently a friend of mine got stopped for tinted windows. He had alcohol on his breath, refused the Field Sobriety Test, but blew into the officers field breathalyzer. The result was 1.0…over California’s legal limit. He went to jail. The DA subsequently dropped the charges because their was no documented impairment.

        In the end you have to make a personal choice if do you do or not get behind the wheel of a 3500 lb vehicle after toking up. In making that choice you need to understand the ramifications… the way, the least of which is jail.

        My policy….a hit or two of the vape and I may drive…..depends on the strain I am injesting. More than that or if I am doing edibles it is UBER time or the pizza delivery dude….”Who ordered the pepperoni?”

    • klw

      I agree to a point. First of all coming up with a flawless test will be very hard says the company in Seattle I think that makes the booze testers for the cops. And it does depend on the person, I have smoked for 45 yrs and never had a problem driving or functioning otherwise but I have friends that won’t go near their car afterwards and tell me to drive since it seems to not matter and it doesn’t. Why can I take all sorts of prescription crap and drive or go to work, but not while high?? Much ta-do about nothing. Besides, the states are really liking the extra many millions now in the state piggy bank and the cops being able to chase real criminals. Maybe I don’t drive “better”, but I do just fine like most of us.

  • Hugh Giordano

    Well written article. Thanks.

  • The 5% vs. 225% statistic seems dispositive, unless one is inclined to disregard evidence.

    I also wonder whether the trends of texting-while-driving were considered. That’s the quintessential case of distracted driving.

    • glaucomajim

      Texting , talking on the phone, eating and drinking coffee, putting on make up , petting the dog,yelling at the kids, crying , laughing , adjusting the music , looking at the GPS……….

      • MV 1967


    • MV 1967

      Texting is 1000 times worse than driving high.

      • Majik53

        I would guess 10,000.

  • Sarah Hartzog

    I know people who have used marijuana to quit opiates, xanax and heroin, works wonderfully for that. I’ve heard stories about people driving on Xanax (why is xanax even legal?) and heroin, and that is worse than marijuana! Xanax, heroin and alcohol are all worse.

  • Suzanne Ledo

    I always say the drunk is the one that runs the stop sign and kills you, while a cannabis user sits at the stop sign waiting for it to turn green. All joking aside, no one should be driving while under the influence of any mind-altering substance. I use both occasionally and wouldn’t get behind the wheel while buzzed on alcohol or stoned. There really needs to be a way to test for actual impairment or use of cannabis in the last few hours.

    • MV 1967

      Cannabis does not impair you like alcohol. Not to be compared.

  • Jason B

    You can’t operate motor vehicles while under the influence. It’s really a simple and already matured ‘rule of thumb/law embedded in most North Americans and demonstrated by most North Americans with a grain of sense and responsibility.

    It’s illegal to drive under the influence.

    Do not use any THC/CBD or any other controlled substance while operating a motorized vehicle unless authorized by state/provincial law and Doctor.

    Smoking 23 years, this is really a no brainer.

    • sfagan1

      The problem is you don’t even need to be “high” to get arrested. Marijuana stays in your system for around a month. So, anytime your pulled over and tested, even if you haven’t smoked that day, you could be arrested.

      • FLW

        > even if you haven’t smoked that day

        My problem is that I haven’t smoked in 30 years.

        (If I were Black, or if they knew how much of a card-carrying, commie-pinko-socialist I really am [and proud of it], they’d arrest me anyway.)

      • Jason B

        yes I understand that. My brother and law were discussing the testing and restrictions for people in oil and gas/trades etc. When/if legal, they will need a test that proves influence within reasonable time frame, they could take easy road and use whatever model they use for alcohol. Even though realistically the longest I’d estimate a stone can last is max 4 hours.

        Things will need to change, they will, but it will be a bumpy ride. Just have to ‘do the right thing’.

        • sfagan1

          That might be very difficult since THC levels are different in different strains. I would think the most plausible tactic would be to decide on a THC limit, much like a blood alcohol limit. This would affect those who need a greater amount of THC to help their condition ie., pain, anxiety, etc.

          • Jason B

            Hey, I hear you. But I’m sure they are making weed legal and it will align more with recreational, similar to beer drinkers. You can’t drink and drive, I think it’s insanity to let people judge for themselves ‘how much have I’ve had?’. You know deep down this is wrong, it is inapplicable to the majority.

            Zero tolerance is best policy, take a bloody cab/uber. To do otherwise is purely selfish. If your medicated on a psychoactive, take a cab/uber. Society sets the bar to the 1%, Jeff Jefferys (regardless how you view him) said it best, I can’t stand him but he is dead on re: gun control/substance restrictions.

  • Ima Straight

    Itʻs my understanding that the drivers of the high speed trains in Japan undergo competancy/reflex testing before every shift. With their safety record, why canʻt we learn some things from their testing methods?
    Lack of sleep is a huge safety factor, but does that show up in a urinalysis? No. But a few tokes from weeks ago. Yes!
    Never forget that prisons are a for-profit industry in this country. And lawyers make laws.
    The Ng in a UA tells you nothing about the current competancy of a driver. They are only included in legislation to be a vindictive way to put legal users in jail.

    Any person who uses pot in any form is a sitting duck to be ground through the legal system at any time over this.

    ALL users need to be demanding a different scientific standard from their legislators before they become caught up in the legal system as ʻpresumed guiltyʻ. That is exactly what the numbers mean for you! You can be jailed, with thousands in legal fees, fines and a permanent criminal record. This us happening to people driving WEEKS after last use.

  • The “But What About” argument invalidates any scientific discussion…from medicine to politics! You lost me- a Stanford Fellowship trained researcher – when you threw in the “but what about” argument. You simply cannot say cannabis was found to have an adverse impact on driving…but what about alcohol…but what about opiates! You may want to slow down on any foolish stance that purports to support the safety of cannabis on drivers given what we know about the endocannabinoid system and it’s distribution of CB1 receptors in the brain in regions governing short term memory and psychomotor function. You also referenced a scientific study that is highly credible that appears in which found that in 5115 young adults over the course of 20 years, marijuana smokers performed better on tests of lung function than nonsmokers and cigarette smokers. When you actually read the findings of this study it makes clear the average marijuana user reported smoking up to 3 times a month while cigarette smokers smoked 8 cigs a day! The researchers acknowledge lung function in extreme marijuana smokers can be expected to drop over time as “the improvement wasn’t seen in the heaviest users”…in those who smoked more than 20 times a month.


    The lies and propaganda about Cannabis has been going on for more than 80 years. The truth is Cannabis, up until the late 30’s/early 40’s was legally grown everywhere in the USA and the world. It was a cash crop for most small farmers and had the blessing of the government. It was only when Ford, Hearst and Rockefeller, etc saw that it would impose financially on their dynasties in the paper, plastic, iron, pharmaceutical and petroleum industries, that Cannabis came under fire. So, they passed legislation outlawing it, and then started a smear campaign to criminalize it and now we have 4 generations that have been raised thinking it is the weed from hell, instead of the God given (especially Hemp) vegetation it actually is and rightfully should be allowed to be grown and consumed by everyone and anyone.

  • Justin Keck

    I have a close friend who lost his licence due to epilepsy. (He had a seizure while driving) After he began using cannabis his seizures all but ceased enabling his doctor to write a recommendation that his condition was managed to the point of being able to get his licence back! He hasn’t had a problem driving since!

    • FLW

      > He hasn’t had a problem driving since!

      So far.

      One day, one of the running lights in his car will go out, and he’ll get pulled over. Then the fun will begin.

      I’d be interested, Justin, if you know whether your friend feels high when he drives, at least sometimes? If so, does he equate being high with being impaired? What does he think about the alleged looming hazard [that everyone is worried about] of taking too much Cannabis, actually becoming impaired, and driving? Does he feel the burning desire to drive while maximizing impairment, such as alcohol tends to affect some people?

      Do the anti-seizure properties last for a while after the initial buzz wears off? Not that a little buzz is a bad thing, but inquiring minds want to know. Certainly, if they pick him (or her) up, do a blood test, and Cannabis was consumed in the last few weeks, then it won’t matter if the buzz was gone many hours ago. Not that a little buzz is a bad thing.


  • Todd Burgess

    I’m gonna binge on penicillin and go for a drive, see if i can get into trouble.
    If it ever gets figured out, the cops will find another reason to arrest the hapless. Any time money is to be collected in fines and penalties, there will be legislation to make it so. The enforcers will just be doing their job. Sorry Woody D, it’s just that way.

  • Glen Folkard – GWS Survivor.

    Yea you have become a victim of fake sciemce and their bogus media that every man and his granny believes. They do the same with shark attacks here in Australia. Run bunk stories for the sheep that fire up in a PC outrage. Cannabis makes you drive like a NANA its that simple. Govts are known liars for centuries, the corrupt MSM media and govts are one and the same. Have the same sick directives. Feudalism for ca$h. They want us fighting drunk and punching each other at 2am so it then justifies the increase in their budgets. Psychopaths run the show simply.

    • FLW

      > drive like a NANA

      Love the way Australians can turn a phrase.

      Here in New York, nothing is legal. When I drive in my neighborhood from stop sign to stop sign to stop sign, I brake a little hard and accelerate a little hard with a bit of impatience. (But I come to full stops, because I can’t afford a ticket.) I’ve tried to drive more like a Nana — more gently (for the good of my brakes and MPGs), but I can’t keep it up for more than 45 seconds. I wish I were allowed the Cannabis tool to make the goal easier to achieve. Pretty sure that mixing a little Cannabis with British Invasion would increase the relaxation.

      British Invasion. Hah; sounds like imperialism.

      You know what you do with imperialists? You hold them down while someone else blows smoke in their face until they start to laugh. Then you know they’ve joined the Human Race. Pardon my tangent. Just Legalize It.

  • Sunny Reid

    What I’m trying to understand is, if this country is under Common Law, which it is, why are we sitting here discussing “what if” laws. If a driver hits another car and kills someone, drunk or not, stoned or not, by irresponsible driving, the consequences should not differ. I believe it’s first degree manslaughter. It isn’t a crime till there is a victim. This will draw a lot of flack, I know, but, our justice system is terribly lopsided and extremely corrupted, currently. Victim less crimes account for probably 50% to 75% of our prison population. DUI”s are a large part of these, and ALL of this amounts to nothing more or less than sucking money from our population, and, establishing deadly power over the citizenry of this nation. The drug laws are literally an invalid, unconstitutional excuse to grow the law enforcement community into literal armies. People are forced to take counseling and drug testing, and pay for the services, themselves. As any thinking person knows, counseling helps no one who doesn’t want it. But the big question is, where did law enforcement ever get the authority to require this kind of intrusive procedure. And the answer is, it DOESN’T have the authority, but it has been assumed.

    • Glen Folkard – GWS Survivor.

      Their planned police state (already here) requires us drunk and bashing each other stupid, to justify their existence. The opiate rage is about more also with the alcohol issue and the antidepressants and crazy nerve drugs that everyone is hooked on. Its like Orwell’s 1984′ but with more violence. Simply employ more psycho-sociopaths at executive level as sock puppets and on it goes. A global Gaza is where we are headed ultimately unless someone steps in. Can you see the Communism yet Sunny Reid?

    • FLW

      It takes a lot of Corruption to perpetuate such a huge lopsided system against The People.

    • Lisa Gage

      So many I have talked to think these laws are true right now but alas NOOO way a done deal. Law enforcement is implementing these testing methods and asking ??? after the person’s life has been ruined for a joint they smoked last weekend at the lake! They do not have the authority and now they say if you refuse the test there are huge fines and jail waiting for you. Check it out and see what up at your county sheriff. Also if a person has delivery job in cannabis the so called lic for it is so ridiculous that it is so risky to find job. Jail waits that worker too if the lic is not present now before the laws have even been approved. Is there a special lic for tomato delivery???

  • klw

    Funny how for decades now a large portion of us have been smoking cannabis on a daily basis, taking our kids to school, going to work, dropping off and picking up kids from daycare, shopping, etc with no issues and now all of the sudden it matters. Not Happy with AAA. We have all the info we need and have had it for decades thanks to the rest of the world, as usual the US is way behind. Canada will be legal by 2018, several countries have legalized all drugs with great results, Israel has known since the 70’s of the benefits and is widely used and backed by the Gov. Portugal, Uruguay legalized all with great results. Time to get with the program people!! Mr Sessions should worry about keeping his job and the opiates and be quiet about things he knows nothing about.

  • Michael Milburn

    The standard for cannabis-impaired driving should the same as for alcohol-impaired driving–and actual impairment, not just exposure to a drug, should be measured. My app in the App Store (Android coming soon) called DRUID accurately and reliably assesses impairment from reaction time, hand-eye coordination and balance measures in just 2 minutes, creating an overall impairment score. If individuals have developed tolerance to cannabis, then my app can show it.
    After getting my PhD at Harvard, I have been a professor of psychology at UMass/Boston for 40 years, with a specialty in research methods, measurement and statistics.

    • Ryan_Dyne

      I don’t hear you mentioning attention/distractedness.

      In fact, taking such a test will artificially raise one’s attentiveness.
      (thus turning your test on its head)

      yet I think it’s clear that distractedness is far & away the biggest problem here; look at the stats herein for the different types of drugs.

      • Michael Milburn

        Even in two minutes, distraction occurs, and my app picks this up. We’re calibrating it against the .08 level of alcohol.

        • Ryan_Dyne

          IOW, impaired people get distracted way too easily, even when their attentiveness need has been artificially raised.(?)

          Although, if you’re taking the test with a suspicious officer hanging over you, …

          Best wishes for your test.

  • John Pack

    I think the only bad thing about weed is the laws and ignorance. If a police officer doesn’t like weed you are pretty much screwed. It depends on the individual officer, they pretty much do what they want.

  • Ancient Knowledge

    Like all things in life,practice makes perfect;however devoting 100% of your time to driving,and avoiding any and all distractions,another question all it’s own.

  • viper643

    Technology is the savior. The millenial stoners will have those self driving features on their vehicles. They won’t need a drivers license. Just the ability to punch in GPS coordinates on that gadget they always have on their person. That is the key feature to prevent impaired driving. Miss a key stroke when typing in the coordinates, and the vehicle becomes inoperative. In the meantime; stay out of the passing lane on the Interstate highway.