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Use of Hand Sanitizers Can Cause False Results in Breath Test Cases

Nov 27th, 2017 OWI Use of Hand Sanitizers Can Cause False Results in Breath Test Cases

A recent article appearing in the Journal for Forensic Science entitled The Effect of Alcohol-Based Hand Sanitizer Vapors on Evidential Breath Alcohol Test Results has concluded that police officer use of hand sanitizers prior to the administration of breath tests in drunk driving cases can cause false positive results when the test subjects had consumed no alcohol.  According to the article’s abstract the study was undertaken to determine if the application of alcohol-based hand sanitizers (ABHSs) to the hands of a breath test operator will affect the results obtained on evidential breath alcohol instruments.”

This study involved three common evidentiary breath test devices, including the DataMaster DMT, the device used by every police department in Michigan.  In the study, the subjects were first tested to confirm that they had consumed no alcohol. Subsequently, the breath test operators used either a gel ABHS containing 67% ethanol (beverage alcohol) or an ABHS foam containing 70% ethanol.  Test subjects then provided a breath sample while the breath test operator held the breath tube.  This is in accordance with the standard procedure in Michigan, where the police officer holds the breath tube while the arrested driver blows into the machine.

In the tests involving Michigan’s breath testing device, the DataMaster DMT, positive breath test results were obtained in a whopping 25% of cases!  The highest of these results was a .035%!

It should be noted that there are several safeguards that are intended to prevent the occurrence of false breath test positives such as these.  These include the 15-20-minute observation/deprivation period, and “slope detection,” which is an internal algorithm that purports to detect and report false positive breath test results.  In slope detection, the DataMaster breath test machine is programmed to take readings of the breath sample every ¼ second.  The machine then compares 2 point averages along the “slope” of the breath sample, and if certain parameters are met, the machine will flag the sample as invalid.  The operator will know this because the breath test machine’s evidence ticket will contain one of three status codes; (1) invalid sample, (2) ambient fail, or (3) detector overflow.  It is believed that slope detection, especially when combined with a valid 15-20-minute observation/deprivation period, will prevent the reporting of false breath test results.  The problem is, slope detection does not work!

As the authors of this study conclude:

Each instrument used in this study utilizes proprietary algorithms to determine the validity of breath test results, where each one uses different calculations to determine whether a breath sample is valid. An exhalation profile indicative of mouth alcohol, such as displayed in Fig. 1, did not trigger an “Invalid Sample” status message on every positive test result on all of the instruments suggests a need for more advanced algorithms to determine the validity of breath alcohol test results than those currently employed.

This conclusion is consistent with many other scientists who have studied the subject.  This means that it is entirely possible for a person arrested for drunk driving with a seemingly high breath test result to be totally innocent of the crime changed!

If you have been arrested for drunk driving in Michigan and noticed the officer use a hand sanitizer before or after administering the breath test in your case, then be sure to notify your attorney.  Small, seemingly insignificant facts such as these, can sometimes mean the difference between conviction and acquittal!