Marijuana and Driving Under the Influence

One of the most frequent questions I receive from medical marijuana patients is whether they can drive and smoke. I’ll answer that questions and make a prediction about the future of smoking marijuana and driving.

Can a medical marijuana patient drive after smoking?

Yes, so long as the patient is not under the influence of marijuana.

A patient cannot smoke marijuana while in the act of driving or operating a vehicle.

In general, a person (not a patient) cannot drive with marijuana in their system. Any amount of THC in the blood would be enough to convict someone of the crime operating with the presence of a controlled substance.

However, a medical marijuana patient may have marijuana in their system while they drive. The Michigan Medical Marijuana Act prohibits a patient from operating a vehicle while under the influence of marijuana.

Simply having the marijuana in the blood is not be enough for a conviction of a patient like it would for everyone else. The prosecution must show a patient is actually impaired by marijuana to convict the patient of driving under the influence.

What Does It Mean to Be Under the Influence

Under the influence means your ability to drive a motor vehicle in a normal manner is substantially lessened by marijuana.

The test is whether because of marijuana a person’s mental or physical condition was significantly affected and the person was no longer able to operate a vehicle in a normal manner.

What Will Happen if Marijuana Becomes Legal?

Michigan voters may go to the polls in November 2018 to have their say on legal weed.

Once legalized, the law will have to treat non-patient drivers the same as medical marijuana patients are treated now. This means that simply having marijuana in the system will be not be enough for a conviction. The prosecution would have to show that a driver was under the influence of marijuana to convict the driver.

What Could Happen in the Future?

The possibility exists that marijuana and driving laws could one day mirror the legal scheme for alcohol and driving crimes.

Currently, it is operating while intoxicated of alcohol with a blood alcohol lever of .08 or higher. A driver with a BAC of .08 or higher is considered per se intoxicated under the law.

A person could still be convicted of operating while intoxicated if shown to be under the influence of alcohol, or convicted of operating while visibly impaired with a blood alcohol content of less than .08 if the person is impaired by the alcohol.

No such cutoff for a per se amount of marijuana in the system exists.

The reason is in part because this has never really been necessary. Any amount of THC in the system meant a conviction – how much THC was in the system was irrelevant.

The possibility exists that one day we will see an amount of THC in the blood stream used as the per se amount for marijuana intoxication.

The legal justification for this would be that marijuana still remains a schedule I substance under the federal law.

There would be one major problem with this: The amount of THC in the blood stream does not correlate with impairment in the same way blood alcohol content correlates with impairment. This fact makes it difficult to create a per se amount of THC for intoxication.

Nevertheless, I would expect police and prosecutors to push for a legal limit cutoff for THC in the system.

For More Information

Call Sam Bernstein at 734.883.9584 or e-mail at

Sam Bernstein is a criminal defense lawyer in Ypsilanti and Ann Arbor.

ArborYpsi Law is located at 4158 Washtenaw Ave., Ann Arbor, MI 48108.

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Read More: New Case Give Protections To Medical Marijuana Patients When Driving

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