Michigan Marijuana Commission Releases Report Regarding THC Level While Driving

Sarissa Montague

Public Act 350 of 2016, which became effective on March 21, 2017, created the Impaired Driving Safety Commission Act. This act created a commission within the Michigan State Police and was tasked with researching and recommending a scientifically-supported threshold of ∆9-THC bodily content (hereinafter “THC”) to provide evidence for impaired driving in the state of Michigan. In simple terms, the job of the commission was to determine if there was a specific amount of THC that, if found in a person’s blood, would make operating a motor vehicle with that amount of THC in his or her blood illegal. The analogy, of course, is the legal limit of .08 for alcohol. If a person in the state of Michigan operates a vehicle with a blood alcohol content of .08 or higher he or she will face a prosecution for drunk driving. The commission’s job was to determine if there was a similar limit that could be set for THC. 

The commission, made up of two representatives from law enforcement, a patient under the Michigan Medical Marihuana Act, a forensic toxicologist, two professors, and a doctor, performed a thorough and diligent study of THC and its effect on the operation of vehicles. After considering the information available, the commission found there is no scientifically supported threshold of ∆9-THC bodily content that would be indicative of impaired driving due to the fact that there is a poor correlation between driving impairment and the blood levels of ∆9-THC at the time of blood collection.  “…[B]ecause there is a poor correlation between 9-THC bodily content and driving impairment, the commission recommends against the establishment of a threshold of 9-THC bodily content for determining driving impairment and instead recommends the use of a roadside sobriety test(s) to determine whether a driver is impaired.”

While the commission’s report is 20 pages, the basis of its conclusion can be summarized as follows:

The level of THC in a person’s body is not necessarily indicative of the person’s ability to operate a vehicle. That is, there is not a direct relationship between THC blood levels and the ability to operate a vehicle; a person can have a high THC level and a low level of behavioral decrement or a low THC level and a high level of behavioral decrement. So, setting a limit of THC can fail to detect impaired drivers or can detect drivers with THC in their systems who are not impaired. 

Some people in the field are touting this result as a “win” for marijuana users, but this is not necessarily so. Not having a limit for THC results in an increased dependence on law enforcement officers to determine, without the benefit of a scientific test, whether a driver is impaired. For now, field sobriety tests will be used to assist law enforcement with this determination, but the scientifically-validated tests, which are generally admissible in court, were originally validated on alcohol-impaired subjects, not subjects impaired by marijuana. So, at least for the time being, the outcome of marijuana-impaired driving cases is going to be left to the discretion of the police officer using tests that were not validated for people who are potentially high. As seen in the attached video from Georgia, this can lead to serious problems for people who are suspected of operating a vehicle while impaired by marijuana even though they are not actually impaired by marijuana.

To date, the Legislature has not amended Michigan laws regarding the operating of motor vehicles while under the influence of marijuana since the recreational use of marijuana became legal in this state last fall. That is, the commission’s recommendation has not yet been adopted.

Levine & Levine is staying on top of the developments in this topic of the law and will provide updates accordingly.

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