The Effects of Marijuana on Driving

Like alcohol, the ingestion of marijuana can affect a person’s ability to operate a motor vehicle safely and can result in serious accidents and injuries.


• Decreased car handling performance
• Increased reaction times
• Impaired time and distance estimation
• Inability to maintain headway
• Sleepiness
• Decreased motor skills
• Inability to stay focused

Studies also show that the effects of marijuana on driving pose a greater risk during monotonous and prolonged driving. Further, mixing alcohol and marijuana use may dramatically produce effects greater than either drug on its own.

Like alcohol, marijuana induced driving impairments increase with levels of ingestion. Consequently, marijuana smoking that is contemporaneous with vehicle operation significantly increases the risk of operating under the influence or operating while visibly impaired.

The National Highway Traffic Safety Administration (NHTSA) reports that data compiled from road traffic arrests and fatalities indicate that after alcohol, marijuana is the most frequently detected psychoactive substance among driving populations.

Some studies on the effects of marijuana on driving have shown that ingestion at certain levels may impair performance on driving simulator tasks and on open and closed driving courses for as long as 3 hours.

Although many pro-marijuana activists and industry resources have reported that driving after smoking is not as serious an issue as drunk driving, they ignore the reality of the effects of marijuana on driving.

Although statistics show that drunk driving is a more common occurrence than stoned driving, with the widespread legalization of marijuana in many states, it is seemingly inevitable that incidents of driving under the influence of a controlled and/or intoxicating substance, such as marijuana, will continue to rise.


But it must be kept in mind that regardless of the issue of impairment from marijuana, in Michigan it is a crime to operate a motor vehicle on the highway if the person has in his or her body any amount of a controlled substance listed in schedule 1 under MCL 333.7212. That means that if the blood test of a suspected drugged driver reveals the presence of any THC the issue of impairment is irrelevant as a condition of securing a conviction.

The only exception is in the case of a driver who has been issued a valid medical marijuana card.

The Michigan Medical Marijuana Act, MCL 333.26421 et seq., makes it illegal to operate a motor vehicle while under the influence of marijuana. Importantly, the Michigan Supreme Court in the case of People v Koon, 494 Mich 1, 832 NW2d 724 (2013) ruled that the act protects a qualifying registered patient from arrest, prosecution and conviction for medical use of marijuana.

Consequently, a qualifying patient may legally operate a motor vehicle with THC in his or her system as long as the level does not render the driver “under the influence”.

Unfortunately, the statute does not define or quantify what constitutes “under the influence”.

Certainly medical marijuana users should educate themselves accordingly so that they, too, can avoid being arrested for OWI or OWVI.

Although OWVI is statutorily defined as a less serious charge than OWI, a conviction can still result in life altering consequences. If you are convicted, you could face the following penalties:


• $300 fine.
• 93 days in jail.
• 360 hours of community service.
• Driver’s license restrictions for 90 days (180 days if impaired by a controlled substance).
• Possible vehicle immobilization.
• 4 points added to the offender’s driving record.
• Driver Responsibility Fee of $500 for 2 consecutive years.

If you’re facing an OWPCS, OWI or OWVI charge related to a positive blood test for THC or any other intoxicating substance you should immediately consult with experienced drunk driving Michigan OWI / DUI attorney to discuss the specifics of your case. Please submit the particulars of your situation on-line or call Edward Earl Duke directly at 248-409-0484.

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The Effects of Marijuana on Driving
Article Name
The Effects of Marijuana on Driving
Attorney Edward Duke explains the effects of marijuana on driving and what you can be charged with if you are driving under the influence of weed.
Duke Law Group