Court overturns Kitsap County Ruling that the Drager instrument must calculate the mean by the method approved by the toxicologist as it relates to admissibility under 46.61.506, at the time the test is provided.  The Supreme courts majority opinion confirms that:

1) State law places strict limits on the admission of breath test results into evidence. A breath test is “valid” if it is performed “according to methods approved by the state toxicologist.” RCW 46.61.506(3). And a breath test is admissible only if the breath samples “agree to within plus or minus ten percent of their mean to be determined by the method approved by the state toxicologist.” RCW 46.61.506(4)(a)(vi).

2) The district court is also correct that in 2010, the state toxicologist “approved” “the method” for performing that calculation; it was memorialized in former WAC 448-16-060 (2010). That method required the mean of the four individual test results1 to be “rounded” to the nearest four decimal places prior to determining the plus or minus 10 percent range. Former WAC 448-16-060.

3) The district court is correct that despite those statutes and regulations, the Dräger instrument has never rounded the mean before calculating the plus or minus 10 percent range. Instead, the Dräger was programmed to truncate the mean before performing that calculation.

But the district court erred in ruling that those statutes and regulations require the Dräger machine itself to perform the mean and the plus or minus 10 percent range calculation in accordance with former WAC 448-16-060’s rounding method.  The district court therefore erred in concluding that because the instrument was not programed to perform this calculation by rounding ( the method approved by the toxicologist) its mathematical calculations rendered the test results invalid and inadmissible under RCW 46.61.506, State v, Baker, and our evidentiary rules. The Supreme court reversed holding no relevant statute or WAC requires the Dräger instrument to perform the mathematical calculation range at the time of the test, and the State can prove the foundational admissibility for the mathematical calculation of the mean and the plus or minus 10 percent range at a different time or manner. 

Find the case here.