Marijuana And Driving In Wisconsin By Andrew Mishlove on April 30, 2015

With the legalization of recreational marijuana in Colorado and Washington State, and the prevalence of medical marijuana in many states, we are increasingly faced with legal problems arising from marijuana and driving in Wisconsin. Let’s address some of the questions about marijuana and impaired driving.

Does Marijuana Impair Driving?

First, does marijuana impair a person’s ability to drive? Many of us children of the 1960’s have a personal opinion on that, and mine is that marijuana does impair driving ability. Some people on marijuana become extremely careful. Anecdotally speaking, however, a driver who is hyper vigilant, under anxiety and driving too slow may be quite dangerous. Conversely, in my law practice, we have seen a recent case where a driver with 6.4 ng/ml of delta-9 THC (see below for what that means) made a left turn into the path of our client who was on a motorcycle, and tragically caused her death (we represent her estate). So, we advise against mixing driving with marijuana.

The science, though, is unclear. A relatively recent macro-study (a study that reviews many other studies) found little evidence that marijuana alone impairs driving ability.

REFERENCE: G. Chesher and M. Longo. 2002. Cannabis and alcohol in motor vehicle accidents. In: F. Grotenhermen and E. Russo (Eds.) Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential. New York: Haworth Press. Pp. 313-323.

On the other hand, a recent study concluded that, when mixed with alcohol, marijuana dramatically increases the likelihood of a charge of impaired driving. And let’s be real now, many people like to drink a beer when smoking a little weed.

REFERENCE: Simultaneous Versus Concurrent Use of Alcohol and Cannabis in the National Alcohol Survey, Meenakshi S. Subbaraman* and William C. Kerr. Alcoholism, Clinical and Experimental Research, V.39, Issue 5, May, 2015.

marijauna-driving-wisconsinResearchers analyzed data from two national surveys, from more than 4,000 men and 4,000 women. There were three categories; those who only drank alcohol, those who used marijuana and alcohol together, and those who used marijuana and alcohol separately. The answers indicated that those who drank alcohol and used marijuana simultaneously were more than twice as likely to drive drunk than those who just drank alcohol. The study concluded:

"If cannabis use becomes more prevalent as U.S. states and other countries continue to legalize it, then we need to be prepared to advise people appropriately,"

"If you use both substances together, your risk of drunk driving, and possibly other consequences, may be higher than if you stick to using one at a time."

According to the study, those who used marijuana and drank alcohol simultaneously were also three times more likely to get into fights, arguments, relationship problems, career problems, legal issues, and drinking-related accidents.

How Much Marijuana is Too Much? What is the Legal Limit for Marijuana?

The active ingredient in marijuana is a chemical called delta-9 tetrahydrocannabinol. If a person has been smoking marijuana, this active ingredient will be in his blood. Delta-9 THC typically does not stay in the blood for long (although there are exceptions with chronic users). There are also, however, other, inactive metabolites of marijuana that will be in the blood, and stay there for a awhile. These are called 11 hydroxy THC, and carboxy THC. They do not affect a person’s ability to drive.

Right now, there is a lot of controversy over whether, and how much Delta-9 THC is “over the legal limit.” In Colorado, the legal limit has been set at 5 nanograms per milliliter of blood (5ng/ml).

In Wisconsin, however, it is illegal to drive with any detectable amount of Delta-9 THC in your blood. We often see cases prosecuted with delta-9 THC levels well below 5 ng/ml.

So, the question is: how much Delta-9 THC is considered detectable? That is controversial too! Right now, the State Lab claims that they can detect Delta-9 THC down to 1 NG/ml.

At Mishlove and Stuckert, however, we have successfully fought that claim on several occasions. Attorney Lauren Stuckert has achieved acquittals in cases between 1 and 2 ng/ml.

We believe that we are the only law firm in Wisconsin to have achieved that result.

What If I Have a Prescription For Medical Marijuana?

Twenty-three states now allow medical marijuana. Wisconsin does not. We are, however, aware of a major cancer treatment facility in Wisconsin that is administering marijuana to chemotherapy patients, to treat their nausea. It may not be legal, but it is certainly proper.

So, if you have a valid prescription for medical marijuana from another state, can you drive in Wisconsin with a detectable amount of Delta-9 THC ion your system? The answer is no. You may not drive with a detectable amount of delta-9 THC in your system in Wisconsin, even if you have a prescription and you are not impaired.

This is, to us, a very dumb law. Let’s look at our cancer patient, who is using marijuana to control the horrible effects of chemotherapy. Under Wisconsin law, this person may not drive to the doctor, even if his delta-9 THC level is well under 5 ng/ml, and he is clearly not impaired.

So, what are the takeaways from this? First, do not smoke marijuana and drive in Wisconsin. Wait at least 24 hours before driving. Second, do not drink alcohol, smoke marijuana and drive in Wisconsin. Third, this is true, even if you have a valid prescription for marijuana.

Finally, as the song said, the laws must change today, but it’s gonna take some time…


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Andrew Mishlove and Lauren Stuckert

Mishlove and Stuckert, LLC Attorneys at Law

Mishlove & Stuckert, LLC Attorneys at Law has been rated the #1 OWI/DUI law firm in the state by Wisconsin Law Journal Reader Rankings. Our OWI/DUI specialists have been highly rated by organizations including: 

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