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After hearing testimony over ten days, Judge Brennan of the Massachusetts district court department issued his decision regarding the defense bar’s challenge to the scientific reliability of the Draeger Alcotest 9510 breathalyzer, first deployed in Massachusetts in June 2012. The defense bar’s motion to exclude breath test results from the 9510 machines as evidence against defendants was allowed in part and denied in part.

The court determined that the scope of its inquiry should include: 1) whether the source code of the machines reliably produces accurate results; 2) whether the machines rely on flawed scientific theories regarding blood-to-breath ratio; and 3) whether the methodology of the state police labs responsible for the machines produces unreliable results. The court declined to consider a fourth issue, whether the source code contains security vulnerabilities making it susceptible to intentional manipulation and unreliable results.

Overall, the court concluded that the Alcotest 9510 produces scientifically reliable blood alcohol content (“BAC”) results. The court held that the machines were reliable in terms of the source code and the scientific theories employed.

Regarding the methodology of the state police labs involved, however, the court found that they produced unreliable BAC results because of the absence of written protocols. The court found that without written protocols, “it cannot be assumed that any particular calibrator understood or routinely applied the proper standards in calibrating a device.” Although the state police labs eventually developed written protocols by September 14, 2014, all Alcotest 9510 results prior to that time are presumptively excluded as evidence against a defendant.

The decision affects 535 cases formerly joined in the matter, and an estimated additional two to three thousand that have been stayed pending the outcome. It is not yet known how many of those cases include Alcotest 9510 BAC results prior to the September 14, 2014 date.

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Joseph Waldbaum

Joseph Waldbaum

Joseph Waldbaum has been licensed as an attorney in Massachusetts for the last nineteen years. He has also been a member of the National College of DUI Defense for fifteen years, routinely attending their national seminars. You may learn more about Mr. Waldbaum through his websites at, or You may also reach him by phone at 978.921.4100 or at

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