LANSING, Mich. (USA TODAY) — Michigan could become the first state to adopt a roadside saliva test for marijuana impairment if legislators pass a bill introduced in both the state House and Senate.
A bipartisan group of Michigan legislators is pushing saliva testing and Michigan State Police are championing it. But researchers who have studied the test method said results are inconsistent and especially misleading when applied to regular users of cannabis, such as the more than 100,000 Michigan residents who are allowed to use medical marijuana.
"We need to look to the future," said state Rep. Dan Lauwers, a Republican from Brockway Township near Port Huron, who sponsored the bill.
Los Angeles police are using the saliva tests in field trials, said Don Targowski, a defense attorney in Santa Monica, Calif., who is active in marijuana cases. The Los Angeles police seek to determine "if the evidence from these tests is going to hold up in court."
Motorists would not be arrested simply for failing the saliva test but only after being pulled over for "erratic driving," Lauwers said. The saliva test would add confirming evidence to justify an arrest, just as portable breath testers do in cases of drunken drivers.
But the two kinds of testing aren't comparable, said Professor Brett Ginsburg, an associate professor at the University of Texas Health Science Center at San Antonio. He has studied marijuana testing and cannabis pharmacology for 10 years.
"I don't know what the level (for impaired driving) is going to be on the Michigan tests, but I suspect you'll effectively prohibit many people from driving," especially those who use the drug frequently, such as medical-marijuana users, he said.
Saliva testing attempts to determine a subject's level of THC, the psychoactive component of marijuana that presumably could affect driving. But because THC affects the brain through the nervous system and because saliva is outside the nervous system, a saliva test is a poor indicator of whether behavior might be impaired, Ginsburg said.
In contrast, alcohol "pretty much permeates the entire body, all at once," so there's a strong and almost immediate correlation between the blood level and behavior, he said.
Michigan seems to be the first state "to be moving forward and implementing a saliva test." Ginsburg said.
At a hearing last week of the House Judiciary Committee, medical-marijuana advocates slammed saliva testing as a violation of their right to use the drug freely under Michigan's medical marijuana act. That had Lauwers saying afterward that he would support an amendment to his testing proposal, House Bill 5385, that would waive the test for motorists who could show police they possessed state medical-marijuana cards.
"Law enforcement wants to be able to use whatever new tools are available," he said. The companion state Senate Bill, 0865, was referred to the Senate Judiciary Committee.
But more important than the saliva testing are other provisions of the bill and a companion bill that would get repeat drugged-driving violators off the road more quickly, Lauwers said. The bills would create a statewide notification system for police of pending drugged-driving cases — similar to the notification that tells police of pending violations by alcohol-impaired drivers.
Medical-marijuana users "absolutely want safe roads," said legislative chairwoman Robin Schneider of the Detroit-based National Patients Rights Association, an advocacy group for medical marijuana.
"We just think that because the science isn't perfected, they might want to hold off on using these tests until we know they're accurate," said Schneider, who testified Thursday against the bill.