How to Understand Forensic Blood Tests in Michigan DUI Cases involving Alcohol, Marijuana and other Drugs

Arrests for driving under the influence of Marijuana are up in Michigan, and this means more lawyers are being called upon to understand the complexities of forensic blood testing. The problem is, few lawyers have this expertise, and this is one of the reasons why Barone Defense Firm partner Michael Boyle recently presented on this topic to the Michigan Association of OWI Attorneys.

Part of what Mr. Boyle explained to his colleagues is that there have been many important changes to the way the Michigan State Police Forensic Laboratory conducts their blood tests in drug cases like driving under the influence of marijuana. For example, in recent years, the Forensic Laboratory has purchased new machines for blood alcohol analysis. The name of these blood testing instruments is “gas chromatograph (GC. These instruments use a technique known as Gas Chromatography and with drug testing there is an additional testing called “mass spectroscopy” (GCMS). The old testing method used single column instruments, but the lab now uses head space dual column gas chromatography utilizing a flame ionization detector.

There have also been other changes to the way these drug tests are analyzed, and the results reported. As an interesting aside, while the common nomenclature is to say “blood tests” in fact, the blood itself is literally not actually tested. Here’s a summary of how it works.

After an arrest, either a voluntary blood draw or involuntary blood draw supported by a warrant is conducted.  The blood is typically drawn from a subject’s forearm or elbow pit area into two BD Vacutainer Tubes.  These tubes are designed to accept 10 ml of blood, but often, for many different reasons, less than the designed 10 ml is collected.  This specific tube should also include two other substances, an anti-coagulant, and a preservative.  This sample must also be inverted prior to being placed back in the cardboard box.  Once it is sealed, according the FSD-93, the arresting or present law enforcement officer is to mail the box immediately to the Michigan State Police Forensic Laboratory using first class mail.

Once the box containing the driver’s blood samples is received at the State Lab, the contents will be removed and evaluated by an employee of the lab. This employee is supposed to document what they observe, such as whether there has been any leaking, assigned the sample a laboratory number for tracking purposes, and then places the samples into a refrigerated storage room until testing.

On the day the blood is tested, the blood samples will be removed from refrigerator storage and brought to the workspace of the forensic analyst.  As noted, two tubes are drawn, but only the first tube drawn will be analyzed at the lab. This first tube will be removed to begin the process and will be prepared for testing. Preparation includes pipetting a specified amount of the blood and substance mixture into a new tube, and a volatile substance known as an internal standard will be added to it.

This tube prepared by the analyst now consists of an anti-coagulant, a preservative, the drawn blood, and this volatile substance. This mixture will be heated at a constant temperature until a vapor, or a gas is created above the liquid portion. This is known as head space gas. This gas is then automatically withdrawn from the tube and injected into the (GC) by the Auto-Sampler. It is not done by person but is automated.

Once injected, a carrier gas, which must be pure, that is hooked up to the GC, is utilized to push the subject samples gas through the GC.  As noted above, one of the recent changes at the State Lab was to switch from a single column to a dual column method, which means that the sample gas will enter a diverter where some will go through column one and some will go through column two.

The column is designed to ‘separate’ the compounds or analytes contained within the sample “based on their affinity with the solid phase.” The purpose of this separation is to identify a particular substance based upon how much time elapses before it exits the GC. This is known as a retention time and refers to the amount of interaction the substance has with the column’s solid phase. Each substance has a known retention time, and this is how the analysis “knows” what substance is being quantified.

The GC instrument is “dumb” in that it must be “taught” how to identify and quantify unknowns, in this case, blood alcohol. The GC can do this only because it ‘has been taught’ that ethanol alcohol (the alcohol you drink) has a specific retention time, so anything that “elutes” out of a column at a given time is thought to be the ethanol.  This is known as the qualitative analysis.  But identifying ethanol is literally only half the battle because it must also be quantified.

Ethanol is quantified by using the Flame Ionization Detector (FID).  This means that when the substances exit the GC it passes through a flame wherein a detector calculates the ions that are created when passing through the flame.  This detector, based upon the charge it receives, then will calculate the amount of ethanol believed to be present in that sample.  And with a dual column, this process is completed twice with an FID for each Column.  This detection charts a peak on a graph, known as a chromatogram, and the area under the peak at the predicted retention time for ethanol is calculated as the purported blood alcohol level.  That result is printed out on the laboratory report which will potentially be used as evidence against a client charged with Operating While Intoxicated.

As indicated above, in marijuana cases, the GC also uses a mass spectrograph (MS), in these instances, the analysis sis a bit different. The MS breaks the molecules apart to identify them, and then compares the results with known spectrographs from the library of unknowns. This creates what is loosely called a fingerprint. With GCMS the fingerprint is created, and then compared with other fingerprints known to represent the unknown from the reference library. In the case of marijuana, if THC is being analyzed, then THC has a particular fingerprint and the two fingerprints, the one produced and the one from the reference library are compared. If they match, then the presence of THC is confirmed.

If you have been charged with Operating While Intoxicated involving blood analysis, including alcohol or drugs like alcohol, then you deserve representation by an attorney who understands the evidence against you, can educate you of its significance. After your arrest it would be our privilege to help you win your life back. Contact the Barone Defense Firm today.

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