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Are Breath or Blood Tests in DUI Cases Ever Wrong?

Sep 1st, 2016 Breath Testing Blood Testing

The strongest piece of evidence in most Michigan DUI cases is the breath or blood test.  In fact, many attorneys think the breath and blood tests are impossible to beat.  Seasoned drunk driving defense trial lawyers however know this to be untrue.

Tests for breath or blood alcohol fall into the broad category of “forensic science,” and it’s fair to say that the integrity of forensic science as a discipline has been recently called into question.  In fact, “false accord that has been granted over time to certain forensic disciplines in our criminal justice system, disciplines that despite widespread acceptance by criminal courts are, in final analysis, mere “superstition.”[i]

But are breath and blood tests in DUI case really merely superstition and not science? This excellent question can probably not be answered with a simple yes or no.  Regardless however, courts and jurors have afforded these tests too much weight and this has undoubtedly leaded to improper if not actually wrongful convictions.

Let’s be clear about this; breath tests are based on infrared spectroscopy.  There is no doubt that infrared spectroscopy is a sound and “real” science.  Where this real science sometimes goes amiss, however, is in its forensic application; the way police officer’s maintain and use the equipment, and lack of real quality control in standards used in the calibration and calibration checks of the equipment.  There is also the potential for a great deal of biological variability that can lead to false results.  Variability that is otherwise not accounted for or explained to the jury.

Much the same can be said about blood testing where gas chromatography is used to measure the blood alcohol.  Again, it’s not the science that is faulty, but the forensic application of the science.  This is due to the sometimes obscenely bad quality assurance and quality control that passes for “science” in some forensic labs.

The real problem comes when the evidence is presented in court.  Because it has the appearance of real “good” science, and because it is presented by believable witnesses, and because it is presented in drunk driving cases, breath and blood tests are rarely questioned.

If you think you were wrongfully accused of drunk driving in Michigan, be sure you find and hire a lawyer with the proper credentials in science.  Otherwise, your lawyer is likely to be blinded by the forensic “science” and you will be wrongfully convicted.