The Truth About DWI Breath Testing: "A .08 may not be a .08"

Posted On February 05, 2016 Charles Ramsay

I've been known to say, "I don't math," but I'm not afraid of science. Here at Ramsay Law Firm we embrace science. Our own Chuck Ramsay is the only Minnesota attorney to be designated a Forensic Lawyer Scientist by the American Chemical Society.

While "good enough for government work" may pass muster at the Minnesota Bureau of Criminal Apprehension, we hold the state to a higher standard: proof beyond a reasonable doubt.

When it comes to breath alcohol concentration testing, the BCA is asleep at the wheel.

In a late afternoon interview yesterday, Chuck told Fox 9 News:

We've learned that the Minnesota Crime Lab is hiding the ball. Essentially, they aren't reporting the true values of these tests. And they're misrepresenting the test results. A .08 may not be a .08.

When we challenge the scientific validity and accuracy of the state's breath test evidence, we call in career scientists, like international measurement expert, Dr. Janine Arvizu. (If you've watched Netflix's "Making a Murderer," Janine is the expert who testified about the FBI's failure to find the preservative EDTA in the blood samples found in Teresa Halbach's vehicle.) At a recent hearing, Chuck asked Dr. Arvizu, "Are the state's breath test results [in our client's case] scientifically valid and reliable?" Dr. Arvizu responded "No. They are not."

The two main reasons why the BCA's breath test results are unreliable: failure to report bias and uncertainty of measurement.

With bias, the state averages the biases of its entire fleet of breath testing instruments; the BCA never calculates or corrects for the bias of each individual machine. As Chuck explained to Fox 9:

Let's say we have two bathroom scales. My bathroom scale, of course, is reading high. And yours, which is probably reading a bit too low. If mine is showing it's five pounds too heavy, and yours is showing it's five pounds too light, together, if you average the bias of the two, it will be a zero. And it will give the false impression that both scales are perfect when individually they're not.

Furthermore, the state refuses to report uncertainty of measurement. As a matter of fundamental, generally accepted scientific practice and procedure, after correcting for bias (which the BCA does not do),

[scientists] have to calculate the uncertainty of the measurement for the breath test. The state already does this for blood and urine tests, but they refuse to do it for breath tests.

According to the bible of standard scientific operating procedures, ISO 17025, "without information on uncertainty, there is a risk of misinterpretation of results.|

No scientific test is valid, accurate, or reliable, without a quantitative assessment of the uncertainty of measurement. We're treating this as a "teachable moment" for the BCA.