Michigan voters could soon be deciding whether to legalize recreational marijuana if a petition drive to get the question on the 2018 ballot succeeds.
A new study released by the Governor's Highway Safety Association suggests the state should learn from places recreational pot is already legal.
Lesson number one: don't wait until it's legal to prepare for impacts on impaired driving laws.
Association spokeswoman Kara Macek says police officers will need additional training to identify high drivers.
"Police officers need to change their mindset from possession of marijuana to impairment by marijuana," she said. "They will need to be able to identify signs of impairment, and not focus on level of THC."
Macek says it will be harder to devise impaired driving laws that apply to marijuana than ones that relate to alcohol use. That's because habitual users of marijuana, including those who use it for medical reasons, can have high levels of THC in their systems — and yet not be as impaired as someone who only uses the drug occasionally.
But she agrees the state will have to set some sort of maximum blood level of THC and be able to back it up with toxicology tests. That will likely require additional toxicologists so lab tests don't get backlogged.
The research on the dangers of driving while high is not as clear as the ample research that's been done on the risks of driving drunk. A study by the Highway Loss Data Institute shows that legalizing recreational marijuana use in Colorado, Oregon and Washington has resulted in collision claim frequencies that are about 3 percent higher than would have been expected without legalization.
Macek says more research on the effects of driving while under the influence of marijuana is needed. But she says there should still be public education campaigns to counter the myth that it's safe to drive while high.