Can a DUI Attorney Challenge Breathalyzer Results?

Posted by Jon Ibanez on May 21st, 2017

When people think of a DUI stop, two things immediately come to mind; the field sobriety tests and the breathalyzer. I can tell you without going into much detail here that field sobriety tests are designed for failure. If you would like more details, see many of the previous articles I’ve written on the fallacies of field sobriety tests.

But what about the breathalyzer? Are they inaccurate as well and can the results of a breathalyzer be challenged?

A number of studies have shown that breathalyzers are often inaccurate. That too is a discussion for a different time. But the more important question, since breathalyzers are generally inaccurate, is whether a breathalyzer result can be challenged in court.

Unfortunately, the California Supreme Court in 2013 ruled that, although breathalyzers are generally inaccurate, scientific evidence challenging the accuracy of breathalyzers in California is not admissible as evidence in DUI trials.

The ruling stems from the 2007 DUI stop of Terry Vangelder. Vangelder was stopped for speeding in San Diego. Although having admitted to consuming some alcohol, Vangelder passed field sobriety tests. Vangelder then agreed to a preliminary screening alcohol test (an optional roadside breathalyzer) which indicated that Vangelder’s blood alcohol content was 0.086 percent. Based on that, Vangelder was arrested and transported to the police station where he submitted to a chemical breath test (a required post-arrest breathalyzer). This breath test showed a blood alcohol content of 0.08 percent. Vangelder then submitted to a blood test which indicated that his blood alcohol content of 0.087 percent.

At trial, Vangelder called Dr. Michael Hlastala, a leading authority on the inaccuracies of breathalyzers.

"They are (inaccurate)," Dr. Hlastala testified before the trial judge. "And primarily because the basic assumption that all of the manufacturers have used is that the breath that [is] measured is directly related to water in the lungs, which is directly related to what’s in the blood. And in recent years, we’ve learned that, in fact, that’s not the case."

The judge however, did not allow the testimony and Vangelder was found guilty. Vangelder appealed and the appellate court reversed the decision in 2011. San Diego City Attorney, Jan Goldsmith, then appealed the appellate court decision arguing that such testimony would undermine California’s a per se law making it illegal to drive 0.08 percent blood alcohol content or higher.

Unfortunately, the California Supreme Court sided with Goldsmith.

“[T]he 1990 amendment of the per se offense was specifically designed to obviate the need for conversion of breath results into blood results — and it rendered irrelevant and inadmissible defense expert testimony regarding partition ratio variability among different individuals or at different times for the same individual," Chief Justice Tani Gorre Cantil-Sakauye wrote for the court. "Whether or not that part of expired breath accurately reflects the alcohol that is present only in the alveolar region of the lungs, the statutorily proscribed amount of alcohol in expired breath corresponds to the statutorily proscribed amount of alcohol in blood, as established by the per se statute."

The Court went on to say that, “Although Dr. Hlastala may hold scientifically based reservations concerning these legislative conclusions, we must defer to and honor the legislature’s reasonable determinations made in the course of its efforts to protect the safety and welfare of the public."

Sounds to me like the Supreme Court is willfully ignoring science simply because the legislature was well intentioned. Sounds like flawed logic.

While people can no longer challenge the accuracy of breathalyzers in general, people who are suspected of DUI in California can still challenge the accuracy of the particular breathalyzer used in their case.

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