WA Supreme Court Reverses Kitsap County DUI Case Decision Challenging Breathalyzers

Illustration of rewind button on courtroom by Barbara Kelley

Recently, the Washington State Supreme Court decided State v. Keller. The Court’s decision reversed a 2022 Kitsap County District Court decision that ruled breathalyzers inadmissible in court. This high-profile case is discussed in a prior blog post due to its potential to affect on hundreds of DUI cases in Washington State.

In 2022, the Kitsap County District Court ruled breathalyzers inadmissible in court after it said it found state regulations surrounding the machine used by the Washington State Patrol were not followed.

The decision was a result of a case where in 2020 a Washington state man crashed his vehicle and failed a breath alcohol test. The man challenged the admission of the results and argued state regulations had not been followed.

The breath test machine, the Dräger Alcotest 9510, was approved by the Washington State Patrol toxicologist in 2010 and has been in common use since 2015.

The Drager machine determines someone’s blood alcohol level by calculating the average of four samples. Under state law, the calculations are rounded to four decimal places, however, the machine truncates rather than rounds to four decimal points.

The court agreed with the man’s arguments that regulations had not been followed and excluded the test results. The court ruled that statutes and regulations require the breathalyzer machine to perform the calculations itself.

Furthermore, court documents said the toxicologist knew about the calculation error and didn’t disclose the information until 2021.

The Kitsap case bypassed the typical appellate process and went straight to the state Supreme Court because of the extraordinary circumstances surrounding the case. The case could have had major implications for thousands of DUI cases due to law enforcement agencies statewide using the breathalyzer machine at the center of the case.

In the decision to hear the case, the Supreme Court Commissioner said, “This decision has the potential to affect a great number of Washington prosecutions for driving under the influence; this case involves significant public interest questions.”


In its decision, the Supreme Court said current statutes and regulations don’t require the breathalyzer machine to calculate the average of the tests itself at the time of the test for it to be admissible in court. The Court said no source of law requires the calculation required by former WAC 448-16-060 to be performed by the breath test instrument. Also, the breath test results can be calculated in a different manner, as long as the different manners meet all other rules on admission of evidence in a criminal trial. Finally, the State can lay foundation for admitting the breath test by performing the required calculation at a later time.

With that, the Court reversed the district court’s evidentiary rulings and suppression order.

Please contact my office if you, a friend or family member are charged with DUI or any other crime. Hiring an effective and competent defense attorney is the first and best step toward justice.