Andrea Robertson 206.395.5257

After nearly three years of suppressed breath tests in King County district courts, due to what has affectionate been known as the “FUBAR” ruling (State v. Ahmach), the practice of DUI defense is about to get a bit more complicated. Following a full week of testimony, and a half-day of closings, the defense team (Ted Vosk, Kevin Trombold, and Andy Robertson) received a ruling back from the 3-judge panel. Actually, two rulings – one indicating that suppressions under the previous Ahmach ruling would no longer happen. And a second ruling, really an extraordinary 31-page treatise on an area of forensic science that has been neglected. The reporting of uncertainty.

First, credit where it’s due. The Washington State Patrol Toxicology Lab has conducted some overhauls in both personnel and protocols. There have been some fairly major changes in how business is conducted in the Lab.

However, with a remnant of the historic attitude of “trust us, we’re scientists and we know,” the State Toxicology Lab and the King County Prosecutor’s Office have refused to concede a point which has widespread support in the scientific community : that is, measurements mean NOTHING unless you have the context of the “uncertainty” inherent in the measurement.

“Uncertainty” seems to suggest that the results are a mere guess. But that’s not the case. Showing a measurement’s “uncertainty” (a/k/a “margin of error” to non-scientists) does not mean that the measurements are inaccurate, false, or a shot in the dark. It simply shows the overall context necessary to judge the numeric values. After all, a measurement of anything is only a “best estimate” of the measured item’s true value. The value itself can never be actually known.

The media coverage of this historical ruling has been very disappointing. Most seemed to parrot the State’s press release, or they quote the WSP’s ridiculous complaint about how onerous this “burden” is, and how pointless the practice of reporting uncertainty is.

There are two responses to this preposterous claim from the State:

First, all the judges order is that the defendant, judge, and jury know the TRUTH. No more, no less. In fact, they commented that “a breath-alcohol measurement without an uncertainty measurement does not tell the “whole truth.” And for many cases, the reporting of uncertainty actually strengthens the evidence against the defendant. When it is most important to defense attorneys is when the reporting of uncertainty illustrates a real possibility that the “true” value is under the legal limit. And as we learned in the hearings, sometimes that possibility is LARGE. One test value was over 50% more likely to be under the limit than over the limit. Which means that the State could not even show by a preponderance of the evidence that the breath test was over the limit. For the State to testify on the face of the ticket alone that they believe it’s over the limit *beyond a reasonable doubt* shows an amazing lack of insight, as well as a failure to provide justice. That can mean the difference between a guilty or a not guilty verdict!

Second, the time it takes to make this calculation is literally 5 minutes once per year on each instrument. The judges heard, understood, and accepted the science and process described during the hearings. No witness for the State could deny that a spreadsheet could easily complete the calculations necessary to provide confidence intervals for any possible breath test mean. When the instrument goes through its quality assurance procedure, the technician then has all information necessary to plug into a spreadsheet (using a formula that has ALREADY BEEN APPROVED by the State Toxicologist), and print out a table showing the confidence intervals for any breath test mean (the average of the two test samples added together, which is the starting point of a confidence interval calculation for any test ticket). This table could be provided to all defendants tested on that instrument, and could be testified about at the time of trial. NONE of this is a burden, or if it is, it’s miniscule. And can hardly be claimed to be a burden when it only makes a case more just and fair, regardless of the ultimate verdict.

It is really extraordinary that the State believes this is some defense “trick” when the judges spent weeks considering these complex issues and published a very thorough, thoughtful, and just opinion. In its elegantly worded ruling, the judges begin by stating that “historic standards of justice – contained in the federal constitution, case authority and court rules – require that the State present breath test readings, both in pretrial discovery and at trial, showing their true value, rather than wrapped in such a way that a false picture is presented, either to the defendant or to the trier of fact.” (emphasis added).

The opinion concludes by stating that “Attaching a confidence interval to a breath-alcohol measurement is, at the same time, both impressive – in the increased reliability of all breath test readings – and stunning – when it is seen that, absent a confidence interval, a “final” breath-alcohol measurement is only a “best estimate” of a person’s breath-alcohol level. Given the requirements of due process, the discovery rules and ER 702, therefore, the State must provide Defendants with a confidence interval for each Defendant’s breath-alcohol measurement. Absent this information, a defendant’s breath-alcohol measurement will be suppressed.”

According to Thomas Bohan, immediate past president of the American Academy of Forensic Science, this is a landmark decision, and a victory for forensic science.

To be sure, this is a game-changer. But we didn’t expect breath tests to stay away forever. Defending them may be tougher now, but the science that the State uses to prosecute its citizens is now much closer to where it should be. With all the attacks on forensic science across the nation, I am proud to have assisted the defense team in a lengthy litigation which forced the State to higher standards of accuracy, truth, and justice.

Andy Robertson is a criminal defense practitioner in Seattle, Washington. You can read more about her practice at