Drivers under influence of marijuana pose challenge for law enforcement after Illinois weed legalization

CHICAGO (WLS) -- According to AAA, drivers under the influence of marijuana are twice as likely to be involved in a crash, and yet an alarming number of people don't think it's dangerous to drive while high.

Recreational marijuana is set to be legal in Illinois on January 1, 2020, after the General Assembly passed HB1438 at the end of May. As the state prepares for the impending law change, the new report from AAA revealed a high number of people, particularly millennials, don't think driving under the influence of marijuana is dangerous. Some of them, in fact, perceive it as less dangerous than driving under the influence of alcohol or driving while drowsy.

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"Fifteen million Americans have driven within an hour of using marijuana in the last 30 days," said Beth Mosher, AAA. "It's alarming to us, the perceptions that are out there."

According to toxicologists, the impairing effects of marijuana are usually experienced within the first one to four hours after using the drug. But because of the different strains and strengths of marijuana, and the different ways of ingesting it, how long the impairment lasts differs, so unlike alcohol, it's hard to know how much time to let pass before getting behind the wheel of a car.

"There is period when you feel high," said Dr. Jenna Nikolaides, Rush University Medical Center. "Obviously you shouldn't drive during that period, but even after the subjective feeling of the high wears off, there are still deficits in memory, reaction time and retention."

Another problem arises in those who combine the use of alcohol and marijuana and then drive. Doctors believe it will raise a whole new set of challenges for law-enforcement.

"The impairment of both combined is probably more than each individually," Nikolaides said. "So you might be under the legal limit for alcohol. You might be under .08, but you might be significantly impaired because you combined it with marijuana."

Doctors said it's likely law enforcement conducting traffic stops will have to go back to field sobriety tests, rather than just rely on blood alcohol tests to determine impairment. That's just one of many things that need to be worked out as the state moves forward with marijuana legalization.