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Michigan Breath Test Defenses

These are the top 9 defenses to a breath test in Michigan.  We have used all of them in defending our clients, and know how to use them in your case to beat the breath test.  Contact us today to learn more!

  1.  Operator Error – This is a very common problem that we see as we look at the videotape of the breath test being administered.  Problems include a failure to observe the subject for at least 15 minutes before administering the test (as required by Michigan’s administrative rules) or the failure to check the mouth or read the chemical test rights.  See Violation of Breath Testing Administrative Rules Might Lead to Suppression of Results for more information.
  2. Abnormal Hematocrit –  This basically deals with the make up of the blood and varies from person to person.  Hematocrit levels can change the corresponding breath test results. The only way to know your hematocrit level is to test your blood for it and we know that wasn’t done!
  3. Changes in Barometric Pressure –Barometric pressure impacts parition ratio.[i] As partition ratio changes, so to does your breath test result.  Anything that changes barometric pressure, including altitute and weather can impact your breath test results making them unreliable.
  4. Improper Machine Maintenance – As we cross examine the individuals involved in keeping the DataMaster properly maintained we often find rules that were not followed and problems that can lead to false results and not guilty verdicts at trial!   
  5. Problems with Simulators – Simulator solutions are solutions of water and alcohol.  These are used to test the DataMaster. If the simulators that are used to calibrate and test calibrations are not properly prepared or used, the results are meaningless.  [ii]
  6. Radio-Rrequency Interference –  If the cops had their radios on or if you were using your cell phone in the room with the DataMaster, your results could be too high!  See Radio Frequency Can Cause Falsely High Breath Test Results for more information.
  7. Breathing Pattern – The longer you blow the higher you go. This is because more breath equals more alcohol and the cops often make you blow as hard and as long as you can.  According to Dr. A.W. Jones: [T]he subject’s manner and mode of breathing just prior to providing breath for analysis can significantly alter the concentration of alcohol in the resulting exhalation. Hyperventilation . . . lowers the breath alcohol concentration by as much as 20% compared with a single moderate inhalation and forced exhalation used as control tests. “Holding breath for a short time (20 seconds) before exhalation increases the alcohol concentration in exhaled air by 15%.”  Michigan scientist Dennis Simpson has found that deviations of between .02 and .04 based on breathing pattern alone. This alone brings a .11 down to a .07!
  8. Breath Temperature – If you had a fever when you blew into the machine, your test result would be too high.  This is because of Henry’s Law and Partition ratio.
  9. GERD – Better known as heartburn, GERD can cause wildely elevated breath test results.  If you suffer from heartburn, call us to learn how we can use this to defend against your breath test result.  See GERD Can Falsely Raise Breath Test Results for more information.


[i] See Leonelli, et al, “Altitude Effect on Alveolar Ethanol Analysis,” 40 Aeros. Med. 1388 (1969);

[ii] See Dubowski, Breath Alcohol Simulators: Scientific Basis and Actual Performance, 3 J. Anal. Tox. 177 (1979).