Researchers Say a Breathalyzer Used in Multiple States Produces Incorrect Results

Two researchers say a police breathalyzer, used across the US, can produce incorrect breath test results, but their work came to a halt after legal pressure from the manufacturer.

This most recent skirmish began a decade ago when Washington state police sought to replace its aging fleet of breathalyzers. When the Washington State police opened solicitations, the only bidder, Draeger, a German medical technology maker, won the contract to sell its flagship device, the Alcotest 9510, across the state.

But defense attorneys have long believed the breathalyzer is faulty.

Jason Lantz, a Washington-based defense lawyer, enlisted a software engineer and a security researcher to examine its source code. The two experts wrote in a preliminary report that they found flaws capable of producing incorrect breath test results. The defense hailed the results as a breakthrough, believing the findings could cast doubt on countless drunk-driving prosecutions.

The company that makes the breathalyzer sued the researchers to prevent release of their data.  ZDNet (May 10, 2018)
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Most any attorney will tell you that You Should Never Take a Field Sobriety Test (SFST). These tests are voluntary, are subjective, and generally are not accurate. However the breathalyzer is "mandatory" under implied consent laws.

Every driver in the State of Washington (and other states) impliedly consents to providing a breath or blood sample after being arrested for DUI. Failure to provide such a sample after a lawful request is known as a “refusal”.

For a Washington Court or the Washington Department of Licensing (DOL) to find that you have refused to provide a properly requested breath or blood test, a number of things must be proven. First you have to have been read or been allowed to read what are know as your implied consent warnings.

It is important to note that behavior apart from saying, “I refuse” can constitute a refusal. An officer may construe a refusal in cases where a person delays too long in making a decision or pretends to blow into the breath tube. This is known as a constructive refusal and while it may be harder to prove than an actual refusal, Washington DUI law does recognize it as a refusal nonetheless.

So, while you are required to submit to the breathalyzer under implied consent laws, and the result of the test can be used against you in court - it seems that the breathalyzer can produce incorrect results, casting doubt on countless convictions.