Michigan State Police stops marijuana testing after false positives

Michigan State Police have acknowledged that its blood tests for marijuana are producing false positives for THC, and it will immediately halt testing.

The Michigan State Police Crime lab notified county prosecutors about the faulty testing on Thursday.

The toxicology tests failed to distinguish between THC, the active ingredient in marijuana, and CBD, a non-psychoactive chemical compound that does not produce a high.

“The MSP Forensic Science Division is examining a discrepancy discovered earlier this week in THC blood testing results in which the presence of CBD in a blood sample may have led to a positive result for THC,” MSP spokesperson Shanon Banner said in a statement. “Out of an abundance of caution (MSP) today notified the Prosecuting Attorney’s Association of Michigan that we are immediately halting the processing of all THC blood samples as we work to learn more and/or until we can institute another validated method of testing to ensure accuracy.”

The discovery raises serious questions about past arrests and could undo convictions that were based on the faulty testing.

While recreational marijuana is legal in Michigan, driving while high is still a crime.

In an email to prosecutors, Cheri L. Bruinsma, executive director of the Prosecuting Attorneys Coordinating Council in Michigan, said the testing results should not be used for prosecutions.

“They are working to understand the issue and scope of the problem,” Bruinsma said of state police. “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.”

It was not immediately clear how long the tests have been faulty or how many people have been impacted.

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