Driving while high: Wayne State professor works to find legal limit for marijuana

Posted at 4:35 PM, Feb 22, 2019
and last updated 2019-05-19 11:37:57-04

(WXYZ) — According to Michigan State Police, more drivers involved in crashes, even deadly ones, are testing positive for cannabinoid drugs. In early January, a 15-year-old boy was killed in Shelby Township by a driver that we're told reeked of marijuana. Police say too often, people don't realize the hazards of driving while high.

"A lot of people have the perception that if it's legal, it's OK. Well, it's OK to smoke, it's just not OK to drive while you are under the influence of smoking," Lt. Derek Lindsay of the Monroe Police Department said.

Lindsay heads up the vice unit for Monroe PD, and he says now that recreational marijuana is legal, they expect to see more people driving high with THC in their system. THS is tetrahydrocannabinol, and it can affect a driver's attention and ability to react.

"Marijuana today is 20-25 times stronger than it was 20 years ago," Lindsay said. "Responses to questions are always slower. When you ask them to do a field sobriety, everything just seems to be in slow motion."

Right now in Michigan, unlike alcohol, there is no set legal limit of marijuana intoxication while driving. If you fail a field sobriety test and police find any amount of THC in your system, you'll be facing a judge.

"With alcohol, you have the .08 and you go to jail for drunk driving, or here's your ticket for drunk driving. We have to do a blood draw, which is going to take time to get the results back," Lindsay said.

At Wayne State University, Pharmaceutical Sciences Professor Randall Commissaris and his team are researching marijuana and it's effects on driving with a simulator and blood draws from their test subjects to measure nanograms of THC.

"We've got .08 for alcohol, is there a number that might be useful for marijuana, because that would be much more helpful for police in terms of enforcement," Commissaris said.

Derek Bandy, a heavy user of medical marijuana, volunteered to get high and then drive the simulator. He had some trouble but drove better than people tested.

"I'm a heavy user so I have a good tolerance and it doesn't affect me as much, but someone who has the same amount of cannabis that I just took, who is a brand new user, might not be able to function," Bandy said.

"Without having some sort of effect-based level, police are kind of hamstrung and they end up with a situation where if there is any marijuana, they sort of have to suspect that it's causing a problem," Commissaris added. "It could be a very low concentration that was from yesterday or the day before even, and it may not even be relevant to driving performance."

"If you don't have THC in the system, then there is no controlled substance in their system to charge them with," Lindsay added. "In order to charge them with the marijuana, you have to have THC in their system at the time of the blood draw."

Right now, legally it doesn't matter how many nanograms of THC are detected if your system if you've been driving.

"Our goal is to contribute to that discussion of what will become the level that is a cutoff level for THC," Commissaris added.

"Time will tell how the new law affects statistics when it comes to accidents and operating under the influence of drug complaints and fatal crashes throughout the state," Lindsay said.