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What is going on with Michigan Datamaster/ Breath Testing?

By Daniel T. Geherin

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DataMaster breath tests may be inaccurate.

Last week, the Michigan State Police dropped a BOMBSHELL on the criminal justice system:  They sent a letter to local police and prosecutors saying that a popular model of breath-testing was being pulled from use due to possible “fraudulent activities.”  As it turned out, law enforcement officials learned that DMT DataMaster representatives were not properly conducting calibration tests on the instruments yet certifying incorrectly that they had.  In a nutshell, State Police officials confirmed that many test results throughout the State were now called into question for their legitimacy and accuracy. 

Even before this news dropped, most criminal defense attorneys knew that DataMaster tests were far from 100% accurate.  So, defense attorneys often reviewed the calibration reports of these instruments and were forced to rely on the certification reports and attestations of testing.  And, judges and juries were shown these calibration reports to “prove” their accuracy.  Now, all of that is in doubt.  With the built-in “variance” of these instruments (i.e., police and company representatives accepted a small variance between a known and tested level, meaning a .09 result could just as likely be construed as 0.08, or as 0.10), defense attorneys now will purse whether the results are useful/relevant at all.

The Geherin Law Group, PLLC is a Criminal Justice law firm based in Ann Arbor that defends hundreds of OWI cases each year throughout Southeastern Michigan.  Dan Geherin, the firm’s principal owner, is a former prosecutor and board-certified criminal trial attorney with over 25+ years’ experience defending and winning OWI/DUI/OWVI cases in Washtenaw and surrounding counties.   Every day, Dan hears from clients who ask questions like the following:

  • “Why does my breath test seem so high, I didn’t drink that much?”
  • “Why was my DataMaster test so much higher than my roadside PBT test?”
  • “I did fine on my roadside tests, but I’m still being prosecuted for OWI?”
  • “Is there any way to attack/suppress/minimize/explain my DataMaster test at trial?”


"Dan is an amazing attorney. He is extremely intelligent and personable. He and his law firm have been on top of everything with returning calls, emails, etc. his approach to my case was incredible and I am very satisfied with his support and work. I would absolutely 100% recommend." - Jamie M.
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Without question, the breath result (or blood/urine result) is just one small piece of the drunk driving puzzle.  Driving; appearance; statements; performance on roadside tests; witness statements.  A thorough defense of an OWI charge in Michigan requires a full analysis of the whole puzzle.  After all, if the client’s driving and roadside tests were terrible, a lower chemical test might not matter much.  On the flip side, if the client appears sober and passes the tests at the scene, a higher test result might be artificially inflated and need to be challenged. 

Now, with the bombshell news about the DataMaster, prosecutors/police will have to determine how to proceed on cases affected by these fraudulent activities.  Will they dismiss pending cases, irrespective of the result?  Will they only dismiss cases with lower results?  Will they go back and review closed cases, including those where people were convicted at trial or plead guilty?  Lastly, will they fight defense attorneys’ efforts to inform juries about these fraudulent certifications? All of this will need to be watched closely over the next several months.

At GLG Michigan, we start each OWI/OWVI representation with a deep-dive into the evidence, and we contrast that with a client’s version of events.  If a viable litigation challenge to the case exists—including issues with the DataMaster test—you can bet we’re going to pursue it with zeal and aggression.  Now, we’ve got our eyes trained on this new evidentiary bombshell and will continue to use every tool we can to fight for clients’ rights, reputation, freedom and driver’s licenses. 


DUI Attorney in Ann Arbor - Dan Geherin

If you or a loved one has been arrested for a drunk driving offense and are wondering how this DataMaster issue might apply to your case, please contact Dan Geherin, a DUI attorney in Ann Arbor.  We’re available 24/7, and we will help put you at ease, form a plan to handle your case, and fight aggressively to achieve your personal justice.  Schedule online, or call 24/7 (734) 263-2780.   

Geherin Law Group PLLC
DUI Attorney in Ann Arbor, MI