The Michigan State Police recently halted the testing of blood for the presence of THC, citing possible false positive results caused by the presence of CBD in samples. Officials have also alerted county prosecutors across the state to the discrepancy, warning them that they shouldn’t rely on the lab’s test results regarding cannabis blood tests as evidence in pending cases, according to Michigan State Police spokeswoman Shanon Banner.
The pause in laboratory analysis of THC will be in place indefinitely “as we work to learn more and/or until we can institute another validated method of testing to ensure accuracy,” Banner said in an email to the Associated Press.
On August 25, Cheri L. Bruinsma, the executive director of the Prosecuting Attorneys Association of Michigan, sent an email to county prosecutors to inform them of the pause in THC testing at the Michigan State Police’s crime lab.
“We were alerted by the MSP Crime Lab that there is likely an issue with toxicology screens for blood tests for marijuana results,” Bruinsma wrote in the message quoted by MLive. “They very recently learned that the test is unable to distinguish between THC and CBD. They’re working to understand the issue and scope of the problem. They expect to have additional information in the next few weeks. In the meantime, if you have a case that relies on a THC toxicology screening, you should not rely on that result.”
Michigan voters legalized the medicinal use of marijuana in 2008, followed by the approval of a ballot measure to legalize adult-use cannabis in 2018. While driving under the influence of cannabis remains against the law, unlike many states, Michigan doesn’t have a limit for blood THC concentration. In 2019, a commission on impaired driving that included the head of the Michigan State Police recommended against creating a THC limit because of a “poor correlation” between bodily content and driving impairment. However, prosecutors are still permitted to present such evidence in court, according to defense attorney Mike Nichols.
“Somebody gets pulled over and there’s an accident where someone is hurt or killed,” he said. “It’s been a bigger deal since we went medical in 2008. I get more and more cases.”
The problem with cannabis blood tests revealed this week isn’t the first time the reliability of the state police’s laboratory when used for marijuana blood testing has been called into question. Travis Copenhaver, a partner at the cannabis law firm Vicente Sederberg’s Michigan office, says that there “have been concerns over the unreliability of MSP crime lab’s THC toxicology screening for several years now.”
“This seems to be a pattern. In 2015, controversy arose over the testing of synthetic THC, and the fact that their methods have issues differentiating between THC and CBD,” Copenhaver wrote in an email to Cannabis Now. “It’s my understanding that county prosecutors have started notifying the defense bar and judges advising that the crime lab’s THC toxicology screenings are unreliable. Now that Michigan has recognized the legal use of both THC and CBD, this shot across the bow will help MSP bring its testing capabilities into the modern era.”
Even when the laboratory tests return valid results, Copenhaver agrees with the 2019 commission’s assessment that using THC concentration as evidence of impairment is problematic.
“Studies continue to show that THC levels aren’t an accurate means of measuring intoxication. While it would be great to have testing similar to roadside alcohol testing, the fact of the matter is that THC and alcohol intoxication are very different,” he said. “THC doesn’t lend itself to the kind of testing models that law enforcement rely on to police alcohol levels. Driving under the influence of THC is still a significant concern, however, [but] not as significant as driving while drunk.”
It’s unknown how many pending cases the lab testing discrepancy will affect. Michael Komorn, an attorney specializing in criminal defense and cannabis law, said that evidence of THC in blood tests is frequently used to prosecute driving offenses, especially in cases where no alcohol was detected. Depending on how long the lab has been experiencing discrepancies in testing, he noted, thousands of past cases that have ended in convictions and perhaps jail time could be called into question. He’d like to see a full investigation of the state police’s crime lab and the THC testing debacle and has called for the creation of an independent lab without connections to the department.
“I think that it’s time to get a new lab,” Komorn said. “Because the procedures and protocols that are being used here to measure cannabis blood tests , if they’re wrong and unscientific—and they’ve been convicting people wrongly because their tests are wrong—I think a criminal investigation should be opened. I think people should be held accountable.”