Michigan State Police's Forensic Science Division recently learned that current testing methods may not be able to determine the difference between CBD and THC in a suspect's blood. As a result, MSP has temporarily stopped processing blood samples marked for THC testing.
In an interview with Eric VanDussen on Medium.com, MSP Toxicology Unit Supervisor Geoffery French said that MSP/FSD uses a procedure called gas chromatography mass spectrometry (GCMS) to identify the presence of THC in blood samples.
"The problem is specific to the reagents that we're using," French said. "The extraction and instrumentation are perfectly fine."
French went on to say that many labs have updated to newer testing methods, so this discrepancy does not necessarily affect any other police departments.
There's also the question of how many CBD users may have been wrongly charged or convicted due to a false THC test result.
According to French, the MSP/FSD has used this testing process for 20 years. The separate use of over-the-counter CBD is a new phenomenon, though, so French believes the window for potential wrongful convictions is likely much smaller.
On Friday morning, the MSP/FSD informed the Prosecuting Attorney's Association of Michigan that THC testing would not resume until more information can be collected, or until an accurate testing method can be implemented.
MSP is still working to determine the overall impact on past cases that involved THC testing.
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