Michigan Police Lab Has Used Wrong THC Test For 20 Years

The Michigan State Police Forensic Science Department is responsible for testing to determine whether alcohol or marijuana is present in the blood of an individual suspected of driving under the influence.

On Thursday, August 26, 2022 the Michigan State Police Forensic Science Department announced that the method that they have been using to prepare unknown blood samples for analysis has led to inaccurate and invalid results.

Specifically, the method they have been using is not specific enough to distinguish tetrahydrocannabinol (THC) from cannabidiol (CBD). Both are very common cannabinoids contained in the marijuana plant. CBD is not a psychoactive substance – CBD alone does not make someone “high” or impair a person’s driving. THC is the active substance present in marijuana that can impair a person’s driving.

It is THC that the laboratory should be testing for in blood, not CBD. If in fact they have mistaken any amount of CBD for THC, the result would be falsely inflated and therefore invalid.

How did this happen?

It was not until 2018 that Michigan law changed so that the detection of THC in the blood could be considered evidence in OWI cases. Although they should have updated their methods at that time, they have not done so: the MSP lab has been using the same method of testing THC levels in blood for over 20 years.

The MSP lab has been using an invalid testing method for a long time, but its questionable accuracy isn’t recent news. There exist peer-reviewed articles that have identified the potential issues with the assessment procedure. It was called to the lab’s attention at least once by Dr. Andreas Stolz from Michigan State University’s National Superconducting Cyclotron Laboratory.

Dr. Stolz was familiar with the scientific studies and suspected that the wrong methods were being used. “The MSP Lab’s validation studies were not specific nor comprehensive enough to completely validate their methods,” said Dr. Stolz in an exclusive interview.

How many cases will be affected?

It used to be that any amount of THC in a person’s body was per se, or absolute evidence of intoxication for DUI prosecutions. That meant that if a blood test found even 1 nanogram of THC, they were guilty of driving under the influence.

In December of 2018, Michigan legalized marijuana for adults, which includes ‘internal possession’. At that point the ‘any amount’ law overturned, and it was no longer unlawful to have THC in a person’s blood while driving. It is still illegal to drive under the influence of marijuana, and the main evidence in these prosecutions was a THC blood test. So even if there is no longer a “per se” amount of marijuana that equals guilt, the test results are still used as evidence of THC presence and intoxication.

Those test results were considered by both defense and prosecution attorneys to develop litigation strategies. The degree that the test results influenced these strategies is dependent on each case. Therefore, each case must be evaluated individually to determine what should be done about the potentially inaccurate laboratory results.

Can they retest the samples?

It is believed that the MSP lab currently possesses the necessary instruments to perform accurate tests. As a matter of policy, the lab maintains blood samples for a minimum of two years. Therefore, they could re-analyze blood samples via a new, valid method.

This is certain to occur, and once the test results are compared, we will be able to discover the degree of error present. The scientific community will perform its own independent analyses alongside Michigan’s defense lawyers.

How would someone convicted of a marijuana-related OWI possibly get their case reviewed or their conviction set aside?

Each case must be evaluated individually, taking into account all of the evidence that existed including observations of driving, field sobriety testing and the amount of THC found in the blood. An independent test of the blood sample would be useful in reviewing the case and determining whether or not the sentence can be overturned.

The MSP will release more information about the tests and their results soon, which will give Michigan residents the opportunity to develop a more thorough understanding of the issue.

Ultimately, if someone wants to overturn a conviction, a motion must be filed in the court where the conviction was entered and the case took place.