Michigan State Police Crime Lab Halts Cannabis Blood Tests After False Positives for THC

The Michigan State Police (MSP) crime lab is halting cannabis blood tests after false positives for THC were discovered, MI Tech News reports. The Michigan State Police Forensic Science Division has launched an investigation following a discrepancy found last 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.   

Shanon Banner, manager of the Public Affairs Section at the Michigan State Police, said the agency was “immediately halting the processing of all THC blood samples” out of an “abundance of caution” as the agency works “to learn more” or “institute another validated method of testing to ensure accuracy.” 

The issue came to light when freelance reporter Eric VanDussen posted an interview he conducted with MSP Toxicology Unit Supervisor, Geoffrey French, in which French confirmed that his department’s testing for THC levels in blood samples is unreliable and that the MSP Forensic Science Division has been using the faulty testing process for more than 20 years. 

VanDussen: “So this could have implications on prior convictions, as well as pending cases?” 

French: “It is possible. Yes, sir.” 

VanDussen: “How was it that MSP came to the conclusion that they can’t differentiate between THC and CBD after using this method for 20 years?” 

French: “It’s a part of our procedure that worked perfectly fine for analysis for THC and carboxy THC. But unbeknownst to us, there’s an issue if there may also be CBD and carboxy CBD in that blood sample. And we were unaware that some substances may also, be essentially looking like THC and carboxy THC.” 

Cannabis Counsel Principal Thomas Lavigne told MI Tech News that the revelation could overturn some convictions and dismiss others “because juries and judges were misled with fake scientific testimony based on defective lab tests.” 

Frech told VanDussen that the problem wasn’t with the testing instruments, but rather the reagents used in the process. He added that other laboratories have “moved on to other technologies” and that his lab “hopefully” would be moving on to newer technologies as well.