Opinion: Marijuana legalization should not be held hostage to drugged driving concerns

By Paul Armentano

For MarylandReporter.com

Maryland lawmakers are once again considering legislation to regulate the adult use and sale of marijuana to those age 21 or older. Nearly six in 10 residents support this reform, according to a February Goucher poll. But opponents charge that doing so could pose a risk to traffic safety.

Such concerns are not all together unfounded, but deserve to be placed in proper context.

First, it should be stressed that driving under the influence of marijuana is already a criminal offense in Maryland. Nothing in the language of Maryland’s proposed adult use laws changes this reality.

Second, scientific studies consistently find that marijuana-positive drivers possess a comparatively nominal accident risk, particularly when compared with alcohol-positive drivers. In fact, the largest ever controlled trial assessing marijuana use and motor vehicle accidents, published in 2015 by the U.S. National Highway Traffic Safety Administration, reports that marijuana positive drivers possess virtually no statistically significant crash risk compared to drug-free drivers after controlling for age and gender.

By contrast, drivers with detectable levels of alcohol in their blood at legal limits possess nearly a four-fold risk of accident, even after adjusting for age and gender.

This finding is consistent with prior meta-analyses of crash risk data. For example, a review of 66 separate crash culpability studies published in the journal Accident Analysis and Prevention reported that THC-positive drivers possessed a crash risk on par with drivers testing positive for penicillin (Odds Ratio: 1.10 for cannabis versus Odds Ratio: 1.12 for penicillin) This risk is far below that associated with driving with two or more passengers (OR=2.2) and is comparable to the difference between driving during the day versus driving at night.

Data from states allowing marijuana use

Further, data from states that have liberalized marijuana’s legal status show no uptick in motor vehicle crashes. Writing in December in the American Journal of Public Health, investigators at Columbia University reported, “[O]n average, medical marijuana law states had lower traffic fatality rates than non-MML states. …. Medical marijuana laws are associated with reductions in traffic fatalities, particularly pronounced among those aged 25 to 44 years. … It is possible that this is related to lower alcohol-impaired driving behavior in MML-states.”

A review of federal FARS data (Fatal Analysis Reporting Systems) further finds that trends in motor vehicle accidents in Colorado and Washington post-legalization are no different than crash trends in non-legalization states over this same period of time.

Use before driving should be discouraged

Nevertheless, the use of marijuana prior to driving ought to be discouraged and better efforts ought to be made to identify drivers who may be under the its influence. These include greater funding for the training of Drug Recognition Evaluators, the use of modified roadside field sobriety tests, and potentially the provisional use of roadside marijuana-sensitive detection technology, such as saliva test or breath test technology.

These efforts should not include the imposition of per se thresholds for THC or its metabolites, as such limits are not scientifically correlated with driver impairment.

Efforts should also be made to better educate the public with regard to the existing traffic safety laws, as well as to the evidence surrounding marijuana’s potential influence on driving. In particular, this messaging should stress that combining marijuana and alcohol greatly impacts driving behavior and is associated with far greater risk of accident than the use of either substance alone.

Such an educational campaign was implemented nationwide in Canada by the Canadian Public Health Association and could readily be replicated in the United States and promoted by groups like the American Automobile Association.

In addition to increasing public safety, implementing these steps would help assuage concerns that regulating the adult use of marijuana could potentially lead to an increase in incidences of drugged driving or limit the state’s ability to successfully identify and prosecute such behavior.

Adults’ consumption of and demand for marijuana is here to stay. It is time for Maryland lawmakers to acknowledge this reality. It is time to stop ceding control of the marijuana market to untaxed criminal enterprises and to regulate its adult use and sale accordingly.

Paul Armentano is the deputy director of the National Organization for the Reform of Marijuana Laws (NORML) and is the co-author of the book “Marijuana Is Safer: So Why Are We Driving People to Drink.”


  1. Dan

    Transportation as we know it will be vastly different in the coming years as automated cars hit the streets. Something to consider that is completely unrelated to the moral argument that marijuana is bad for you.

  2. Ruben Hernandez

    Alcohol vs Cannabis

    Cannabis and Neurogenesis

    A little Experiment made by the BBC showing that
    driving under the influence of cannabis is not as dangerous as driving
    under the influence of alcohol.

    Marijuana Users Are Safer Drivers Than Non-Marijuana Users, New Study Shows

    Marijuana: Study Finds Minimal Changes in Driving Performance After Smoking

    Experienced Pot Consumers Less Likely To Exhibit Impaired Performance, Study Says

    This study is potentially HUGE! One of the most common attacks on
    medical marijuana reform is that it will cause an increase in traffic
    fatalities. Apparently this assertion is dead wrong:

    Med. marijuana laws = 9 percent traffic-death decline, 5 percent beer-sales dip, study finds

    States That Legalized Medical Pot See Decrease In Traffic Fatalities

    Federal Study Finds Stoned Driving Limits Need Adjusting

    Fed study: Booze impact greater than pot on driving

    Israel News – New study shows marijuana use does not cause traffic accidents

  3. Denise Valenti

    So good that there are functional tests that are being made available. Just the acknowledgement of need to test is powerful. Research and education are key. Having thirty years experience with patients and driving impairment have taught me that.

  4. Denise Valenti

    I think it is exciting that there are non biologic tests of function under development. Since marijuana driving impairment is so complex, there will need to be several tests in order to accurately have a picture of impairment to driving. Driving and marijuana is a concern and it is so much more complex than alcohol. IMMAD – Impairment Measurement Marijuana and Driving…….is a functional test. Blood, saliva or breath measures may not be an accurate reflection of function, but will still be very important measures when determining impairment. Research is needed and it is likely that for a strong case of the driver being impaired there will need to be several functional tests. A problem is there is very little research on humans and marijuana impairment. We know so very little about the impact of marijuana on humans because as a federal Schedule I drug, it is deemed dangerous and thus medical research of “no value”. This has created such a problem in moving the science forward. That said JAMA recently reported that chronic users have a dysfunction in retinal ganglion cells…These cells are critical to accurately process motion, speed, depth and contrast. All important functions for safe driving. The same researchers found that these cells are significantly impaired with acute/recent use of marijuana. IMMAD – Impairment Measurement Marijuana and Driving is a test under development that is a simple two minute tablet application to determine fitness to drive with marijuana use. It capitalizes on the retinal visual impairments caused by marijuana use. It is a direct measure of functions that when impaired result in poor and dangerous driving abilities. The preliminary study of the IMMAD technology is being presented at a cannabinoid research conference being held at Harvard University this April. More research on this and other tests is critical.

  5. Denise Valenti

    DOT HS 812 117 Behavioral Safety Research February 2015
    Drug and Alcohol Crash Risk
    Richard P. Compton and Amy Berning
    This report is available on the internet.
    I think the readers can determine for themselves. The NHTSA reported the entire data set and then analyzed looking at variables….. The final conclusion was after tweaking the data. Yes that is statistically sound, tweaking may not be the technical description …. but it does accurately describe the process. Tweaking changes or reconsiders what the original conclusion was. Your elected to report the tweaked data. Because it came to the conclusions of interest to you. Yes when you control for age; that means consider over the age of 25…including cognitively impaired older adults, when you control for gender- that means you look at those of only female gender-having tweaked other data on males and since the conclusion was not quite where a person who wants to consider marijuana safe, you tweak it some more but this time you tweak the variable of race….and then the variable of having only Caucasians gives the outcome of interest. So when controlled for RACE GENDER AGE….you have a conclusion that is of interest to those who advocate for broad legalization of marijuana. But the report elaborated on all the data and how and why the data was evaluated and tweaked, you did not. And that there was a point to be made is apparent. The comments you provided left out the race based controls of the variables…interesting.

    • DeniseValenti's Mother

      I think you need to take a course in how a study works. Control for gender, age, etc. is saying that each of these groups have a different accident odds ratio that has been taken into account.

      • Denise Valenti

        Those who post anonymously often do so because they have no confidence in the quality of their opinions. I do appreciate that to control for gender, age, race (is there a reason those posting are leaving out that this study controlled for race? Is not it a concern that the opinion was that racial groups are more of risk on our roads than Caucasians? and thus had to be controlled for?) Yes it adjusts for accident odds ratios. BUT THE READERS WHO ARE MAKING DECISIONS ABOUT THE SAFETY OF THE ROADS NEED TO UNDERSTAND WHAT WAS “CONTROLLED” FOR. The readers and voters need to know that while the data controlled for variables that have different odds ratios of potentially killing themselves or another driver on the road if using marijuana, the ROADS ARE NEVER CORRECTED FOR RACE, GENDER and AGE. Without controlling for the variables is the risk a reader takes when they drive on the roads. ANd it is clear that the risk doubled in the states of Washington and Colorado with legal use of marijuana. Let me take some of that back. The elderly, older female perhaps using benzos for a dementia that were not corrected for in this study, but should have been if the study had truly corrected for age, statistically is not driving during the later part of the evening.

  6. DrMichaelMilburn

    Opponents of ending prohibition of marijuana often argue that there is no way to assess marijuana-impaired driving, so marijuana should remain illegal. You should know about the app I have developed called D.R.U.I.D. (an acronym for “DRiving Under the Influence of Drugs”), now in the App Store for the iPad and iPhone (Android version coming soon). D.R.U.I.D. measures reaction time, hand-eye coordination, balance, time estimation, and decision making and integrates all the measures into an overall impairment score. D.R.U.I.D. demonstrates that measuring marijuana impairment is available now, so this argument against legalization fails. The app permits individuals to assess their own level of impairment (or that of the designated driver) and determine whether they are impaired. See more at http://www.druidapp.com

    D.RU.I.D. was recently featured on All Things Considered: http://www.npr.org/2017/01/25/511595978/can-sobriety-tests-weed-out-drivers-whove-smoked-too-much-weed

    and on television: http://sacramento.cbslocal.com/2017/02/28/science-lags-behind-marijuana-impairment-testing/

    After getting my Ph.D. at Harvard, I have been a professor in the Psychology Department at UMass/Boston for 39 years, with a specialty in research methods, measurement and statistics.

    Michael Milburn, Professor
    Psychology Department

  7. Denise Valenti

    It is clear: The rate of death…fatal crashes, that have the driver testing positive for marijuana only, no other drugs or alcohol.. that rate doubled in Washington and Colorado the year after legal marijuana passed. Data can be adjusted for the outcome that is desired. You are only discussing aspects of the full report. The study adjusted for age and gender. ….In their report. You are discussing only that part of the report. When the gender/age data was adjusted, readers may not realize that meant…They took all those under the age of 25 out. They took all males out…. They also took all non Caucasians out. I am not sure why you elected not to discuss this, perhaps it was in order to get the conclusion of no “harm” relative to other causes of impairment; alcohol and benzo/neurodrugs. So what was left in the analysis after these adjustments, were the older Caucasian females. This is biased with the older woman who has dementia and might be taking medications that impair driving. Had there been a true correction for age, the older, female with dementia would have been eliminated with a cut off of an age of 45-55. Now if you do not correct for age (include those 18-25), do not correct for gender (leave in males) and do not correct for race (include Blacks, Hispanic, Etc)… conclusion is that marijuana is no longer the lesser of deadly. The conclusion is that marijuana is harmful.
    I agree that driving should not hold up medical marijuana. But you are not expressing concern for those states that do not yet have medical marijuana, only for the expansion of recreational. For the southern states driving is a very serious concern and it is holding up medical marijuana. One only needs to look at the State of Tennessee and their original approach to marijuana/driving in the medicinal bill. The first bill proposed that if a person had medicinal marijuana, they would surrender their driver’s license. This did not get passed. It is self serving for any group to deny the serious, deadly consequences of marijuana impaired driving. Those that are doing so in order to advance recreational legislation are self serving and selfish. It is very unlikely that those states in the south that are not allowing medicinal marijuana will do so until there is solution for driving issues.

    • DrMichaelMilburn

      Dr. Valenti is not describing the analyses accurately. When you control statistically for variables like age and gender, that DOES NOT mean that males and young people are excluded from analyses. The authors of the report utilized multivariate analyses, so the variance in crash risk associated with age and gender are controlled for, allowing an appropriate statistical test of the actual effect of marijuana-impaired driving on crash risk. And, what are the odds that the NHTSA would manipulate the results to show no effect of marijuana-impaired driving on crash risk?

      • DeniseValenti's Mother

        Her comments here cannot be taken as fact as she clearly has not even read the report or reviewed the data.

  8. Dale McNamee

    Marijuana is an hallucinogenic and should not be legalized…

    Medical marijuana should have its beneficial oils and chemicals in pill or tincture form and not in smokable form…

    Also, we have enough problems with drunk driving and driving while screwed up on prescription medications… Why do we need to add “stoned driving to the mix ?

    They will be discouraged from driving…

    Yeah, sure !

    Just like drinkers who disregard the warnings against drinking and driving and prescription meds takers who disregard the warnings about certain medicines regarding driving…

    Those who support this should be tested for pot, alcohol, and opioid use themselves…

    • 240coda

      Stoned driving is already illegal lets try again.

      • Dale McNamee

        And so is driving after consuming enough alcohol to be “buzzed” and after taking medication that can make one drowsy or otherwise interfere with driving safely…

        And despite all of the warnings and the laws, and penalties ( short of being killed )… They still do…

        Marijuana users will do the same and do we really want that on top of the “DWI/DUI” problems Maryland already has ?

        • 240coda

          Thank you dale. I’m glad you decided to respond. I’m just back in the house from lobbying in Annapolis all day. Oh yea. For you guessed it… the cannabis bills. I will leave you with this Dale Mcnamee because you sound like a really rational guy and open to dialogue .

          Marijuana users are already on the road smoking and driving. A “buzzed” IE drunk driver is 4 times more likely to cause a fatal accident than a stoned driver. I encourage to look at the newest study done by the NHTSA.

          “When it came to just alcohol, the outlook predictably got worse. At a
          blood-alcohol content of 0.05—interestingly, the lower limit suggested by the NTSB and which we support—drivers
          were twice as likely to have an accident than someone who hadn’t
          touched any booze. At the legal 0.08 nationwide limit, that risk climbed
          to fourfold; at 0.12, it was nearly eight times higher.”


          The pdf is the first link in that article. Stoned drivers were found to exhibit three major behaviors when they’re driving. They drive slower, don’t follow as closely, and they have the ability to know subjectively when they’re not able to drive. Drunk drivers cannot say the same thing. Drunk drivers kill more people in America with cars than anyone else.

          and Dale. I’ll be ready to answer any questions you have or help change your mind if you’re willing to talk about it.

          Although you may not smoke and think it’s a horrible drug. I’m really extending to you what I’ve never offered anyone. I will speak with you in private to find out why you dislike the idea of an adult using cannabis that will have no affect on your life. Lets talk.

        • StoneyBalognia

          They’re already doing it and you don’t see mass accidents everywhere…what does that tell you?

        • Dq

          Great Points Dale! People can drink some alcohol and not be impaired. People cannot use marijuana and not get stoned. From personal observation – use of marijuana makes people stupid and lazy and mainly obsessed with the next toke. It becomes a dependency.

    • Gary Paul Gesell

      What a are you talking about I have never hallucinated off of pot the only time I’ve ever even felt close to hallucinating was the very first time I ever smoked something good. Why do we allow people that don’t even use or want to even try to use, make laws about it and report

    • StonyBalognia

      What you don’t realize is that people who want to smoke pot are already doing it; we aren’t waiting for some law to be passed, it is the reason we want the law to be passed. Your world will remain the same because the only thing that will change is the fact that now we won’t go to jail. We are already everywhere and Armageddon hasn’t come yet…just calm down.

      • StoneyBalognia

        Also, marijuana is not a hallucinogen. If you’re going to have a strong opinion, at least due some due diligence to make sure it is an informed decision. There is no excuse for this type of ignorance with google and the interweb.

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