Please do not support the proposed THC/DUI Bill

Open Letter to Legislators on the THC/DUI bill:

I am a social scientist and PhD candidate at the University of Colorado at Boulder, where I have been engaged in research on cannabis for several years. In 2012, Colorado passed Amendment 64 to “regulate marijuana like alcohol.” Since marijuana regulation is new, it makes sense to base regulations for cannabis on those for alcohol, but it is important to remember that this does not make marijuana actually “like” alcohol” in its scientific properties. Cannabis does not work like alcohol, and for this reason, the THC/DUI bill is misguided in trying to set laws as if they are the same.

To justify passing the THC/DUI bill, three solid pieces of evidence are required. First, we should know levels that indicate intoxication. Second, there should be an accepted and reliable way to accurately measure that level of intoxication. Third: there should be proof of sufficient need to encroach on individual rights based on danger to the public. Please allow me to address these in turn.

1. Knowing levels that indicate intoxication. Marijuana is not “like alcohol” in terms determining impairment. The science is simply not there. A nanogram limit cannot yet be clearly and unambiguously linked to impairment. Based on the best evidence currently available (Grotenhermen and colleagues review of the literature in 2005, the Medical Marijuana Industry Group report in 2011, which responded to the first proposal of this law, and William Logan’s 2012 chapter reviewing the literature on marijuana and driving in Mahmoud ElSohly’s book Marijuana and the Cannabinoids), it is clear that we simply don’t know the correct limit over which drivers are impaired. It turns out that inexperienced or occasional cannabis consumers may be subjectively impaired at a much lower nanogram level than medical or social cannabis consumers with years or decades of experience. Logan (2012) summarizes the evidence we have to-date and is clear on the point: it is not possible to use blood tests of THC to distinguish between recent impairment and “more distant higher-intensity marijuana use” (286). For medical consumers or other chronic consumers of marijuana, heightened THC in the blood may last long after the subjective experience of impairment. In fact, maintaining higher levels of cannabinoids in one’s system may be related to medical benefit for those treating severe pain and serious illness.

2. There should be an accepted and reliable form of measurement that indicates intoxication. On the second point, it is crucial to acknowledge that marijuana and alcohol are not the same when it comes to how the body processes them. These two substances are metabolized in completely different ways by the body. Alcohol is water soluble. It is rapidly and evenly distributed throughout the body, and for this reason, breath tests can be used to approximate blood alcohol level, and both tests can be reliably used to indicate impairment. There is no such proxy for cannabis. it’s distribution in the body is based on the unique pharmacokinetics of THC, its distribution in the body and the way it is metabolized. Marijuana is lipophilic, it dissolved in fat, not water, and is metabolized quite differently than alcohol. We do not have reliable estimates that are consistent across different individuals, allowing us to measure levels of impairment with the same assessments we use for alcohol. In fact, breath tests cannot be used to measure cannabis for this reason. Instead, blood samples, the most intrusive type of test, would be necessary. Because blood tests are highly intrusive, clear and unambiguous evidence for such an intrusion on individual rights is warranted.

3. Finally, we should be able to link the use of the substance to a clear public health danger on the roads. Cannabis has not proven to present a similar level of risk in traffic accidents. On this final point, we have to ask, is a separate law warranted when marijuana intoxication is already included under existing DUI-D laws? The answer: no. There simply is not data that suggests cannabis alone greatly increases accidents or risks on the road at a level that warrants a new, separate DUI law specific to cannabis. In the case of alcohol, there are clear and well established relationships showing increased risk of accidents linked with blood alcohol levels. Less data exists for cell phone use and prescription drug use, but those studies have consistently shown significant risk ratios that indicate significant crash risks. The data on marijuana shows lower risks than these other factors. The exception is when marijuana use and alcohol use are combined. Again, Logan’s review of the data on relative crash risk following marijuana use, “studies that made odds ratio assessments based on the presence of the inactive THC-COOH metabolite uniformly failed to show significant differences at the p=0.05 level in rate of accident involvement for the drug-positive drivers” (287). Recent evidence suggests that accident rates decrease in states with regulated medical marijuana. This has been attributed to the reduction of alcohol use in favor of marijuana, resulting in fewer alcohol-impaired drivers on the road, discussed by Time magazine in an article by Maia Szalaviz from December 2011.

For these reasons, those who have studied the issue and reviewed all available evidence do not recommend the use of per se limits without better science. To the degree that such policies are used, they urge great caution, and suggest that other methods for assessing impairment not be discarded or demoted given the lack of credibility on the currently available objective measures.

The current bill under consideration belongs to a dying breed. “Get Tough” policies have been popular among politicians because they have equated with success in the polls, but as more and more people acknowledge that the War on Drugs approach to drug control is a failure, these nonscientific approaches are bound to lose traction with the voting public.

Clearly no one wants impaired drivers on the road, and no one is arguing for that. This THC/DUI bill will do little to help prevent that, and it may end up punishing people who are not impaired. Until objective limits for cannabis intoxication can be clearly determined, measured, and linked to a genuine risk to public health on the roads, we should stick with our existing DUI-D law that already covers drug impairment.


Shelli Newhart Walker

6 Responses to “Please do not support the proposed THC/DUI Bill”
  1. Dr Gene Courter DCSW/LCSW/BCD says:

    Well said.

  2. james says:

    We already have a field test for impairment. solid video evidence of a person failing a field sobriety test (the one currently legally employed) is good enough reason to remove someone from behind the wheel of a motor vehicle. What has been, and will be, demonstrated is that the level of detection previously employed to indicate cannabis use is not indicative of physical impairment. As much funding has already been collected through the persecution of cannabis users; that money should now legally be utilized to support analytical testing to verify any assertion of legal limit. How can an intelligent, informed populace or representative move to pass any legislation prior to collecting relevant supporting analysis. I would hope that people will move to defend the rights they have determined are just by removing from office any one who attempts to minimize or marginalize the will of the people.

  3. Anonomyous says:

    if they just legalize it, i’d be fine not driving.

  4. Frank M says:

    As a past cop and current grower/smoker I have seen both sides of this. First, very very rarely was there an individual that did not also have something else in their system. There may have only been marijuana in the vehicle but they were under the influence of something else also. I never had very many court cases because I was an MP in the army and a US Park Ranger. There were always other things to focus on. Now since I am an ex cop many friends have come out (other park service people) that they smoke. Some of them could smoke a bag of the stuff and never show any signs of being impaired. Now if I smoke I have issue getting to the car so my wife can drive! I dont think they will ever find a way to track it. You would have to get arrested, have blood drawn, be charged with a dui, only to find out in court that the blood test was positive but under the limits of the law. Now even though the charges are dropped, you will still have a record of being arrested for dui. unless they develope a pin prick test that gives results (that will stand in a court of law) right on the spot. I dont know, but I am looking forward to moving back to Cortez, Co.!!

  5. Bill says:

    There can not be a law that favors those of high tolerance to cannabis to those will lower tolerances. Many states already have impaired driving laws, would not matter if the substance was cannabis or benign like off the shelf sleeping pills, you simply can not legally drive impaired.

    That is a major problem with the drunk driving laws today. The drunks complain about .08 blood alcohol content being too low and a setup for arrest and court fees. The way I see it, is if I slam 4 drinks, being 250 pounds and wait 30 minutes I could jump in the car as soon as the bac says .08. Except in that hypothetical scenario I am definitely impaired beyond good driving abilities because I do not have a high alcohol tolerance (I am a pot guy).

    There are those dedicated smokers whom insist marijuana does not effect their driving at all. This is simply not true, at all. Your reflexes, visual perception, decision making are all effected with cannabis use. To drive safely means you wait after using cannabis an appropriate amount of time until you are not impaired. Don’t do it because it’s the law, or not to get arrested but because of your safety and the safety of those other people on the road.

  6. Nicholas says:

    I am currently 29 years old. Roughly eleven years ago I went to a service station to buy some food. Shortly after leaving the parking lot I was pulled over for no reason and then given a DUI/owi for marijuana. All of my family except for my Father said that i deserved my punishment.What followed for me was having an alcohol breathalyzer unit installed on my car(which drains the battery over time) had to bs with a “counselor” a few times and had to attend 8 weeks of alcohol abuse classes. The reason i was pulled over that night was because the store clerk smelled marijuana on my clothing and called the police right after I left the building and they immediately pulled me over because of someone’s slanderous accusation. My father had alcohol problems when I was very young and I remember When my mom forced him to go to treatment. I have never been into using alcohol because I know what damage it can cause. I never thought I would be forced to go to alcohol treatment and blow a 0.0 to start my car(in the winter your saliva freezIes the BAC unit and sometimes it malfunctions) or be handcuffed and put in jail because I went to buy some food. Exactly four years later my Father passed away and Alcohol was one of the many factors that caused his heart failure. I never have been a drinker, but because of “NO TOLERANCE” laws in existence; I am considered an alcoholic. THC/DUI is another way to leech off innocent people as well as another excuse to call someone a “criminal.”

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