What is a Michigan DUI Breath Test 120-Day Inspection and Why Should I Care?

The breath test is the most common chemical test given to drivers in Michigan arrested for DUI. The device used by police throughout the State is the DataMaster DMT.  Like all breath testing devices, this instrument uses infrared spectroscopy to measure the amount of beverage alcohol in a driver’s breath.  To assure accuracy, however, like all measuring instruments, the DMT must be properly calibrated and maintained.  Otherwise, drivers can be wrongfully accused of driving drunk, and worse than that, wrongfully convicted of drunk driving.

To assure this breath test accuracy, the Michigan State Police, who are charged with the responsibility of maintaining nearly all of the State’s DMTs, has promulgated administrative rules for breath testing.  These rules provide that each DMT must undergo a weekly “dry gas” calibration check. These dry gas calibration checks are run automatically.  In addition to this, every 120-days a Class IV operator must inspect the device. During this 120-day inspection necessary repairs can be made, and the breath testing device can be re-calibrated.

The 120-day Inspections

As part of the quality assurance protocol, an evidential breath testing instrument must be “checked for accuracy” once per calendar week , and every 120 days, the instrument must be “certified.”  The administrative rules regarding tests for breath alcohol promulgated and approved by the Michigan State Police, provide in part as follows:

(3) Approved evidential breath alcohol test instruments shall be inspected, verified for accuracy, and certified as to their proper working order within 120 days of the previous inspection by either an appropriate class operator who has been certified in accordance with R325.2658 or a manufacturer-trained representatives approved by the department.

When conducting an inspection pursuant to this rule, a factory trained class-four  operator, will prepare three alcohol solutions from a NIST  traceable standards to create a .04/.08/.20 solution.  The solutions are prepared in a simulator jar into which the standard being tested is placed.  This is called a “wet bath” simulation.  In order to facilitate the transference of the standard into DMT the operator blows into the simulator jar. A vapor produced by the combination of the two travels through the breath tube and into the sample , and then, using human expired breath, the simulator operator will assist the introduction of the solution into the sample chamber of the DMT being “inspected.”

Like the weekly calibrations, the resulting measurements must be within a prescribed range. These three calibration checks ostensibly demonstrate instrument linearity, which is necessary to show that the instrument is capable of accuracy at levels other than those specifically tested. If the instrument fails to demonstrate linearity, then the 120-day inspector is to follow a series of protocols, the purpose of which is to isolate the cause of the failure.  Depending on how the instrument “behaves” during these additional tests, the 120-day inspector may conclude that the instrument is out of calibration.  The 120-day inspector may then either (1) take the instrument out of service, or (2) re-calibrate the instrument himself/herself.  While 120-day re-calibration may be rarely done, the 120-day inspectors are trained to re-calibrate a DMT instrument, and their passwords allow the access to the necessary software and functionality.

I’ve Been Arrested for DUI in Michigan – What Does this all Mean to Me?

Between the periods of September 2018 and January 2020, the 120-day inspectors in Michigan committed fraud during their scheduled certifications. This means all breath tests conducted during this time period are invalid and subject to challenge.  If you were arrested for DUI in Michigan after this time period, this proven fraud can still have an impact on your case, and may result in the charged being reduced and in some cases may even lead to a dismissal.  Contact the Michigan DUI lawyers at the Barone Defense Firm for a case review to learn how this information may apply to your case.

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