California Supreme Court: Breathalyzer Results Can Be Challenged

An article in the Los Angeles Times late last week brought attention to the California Supreme Court’s recent ruling that Breathalyzer findings can be challenged in court:

Under the law, a suspected drunk driver can submit to either a blood test, which measures the amount of alcohol in the blood, or a breath test. Alcohol levels in a breath sample are converted mathematically to derive a blood-alcohol percentage. In California, a person is legally drunk when his or her blood-alcohol level is 0.08% or higher.

The standard formula for converting breath results to blood-alcohol levels is not accurate for everyone, however, and can vary depending on an individual’s medical condition, gender, temperature, the atmospheric pressure and the precision of the measuring device, the court said.

“The question is whether a defendant who has a blood-alcohol concentration of 0.08% or more measured by breath is entitled to rebut that presumption that he was under the influence” in certain cases, Justice Carol A. Corrigan wrote. The court’s answer was yes.

As the article explains, one of the reasons for the ruling was the potential for Breathalyzer readings that overstate the amount of alcohol in a person’s blood:

Even though experts say the standard ratio used to derive a blood-alcohol concentration from breath generally approximates or even underestimates the amount of alcohol the driver consumed, they also agree that Breathalyzer results may sometimes overestimate the amount of alcohol in the blood.

Thursday’s ruling permits defendants in some cases to challenge those results based on mathematical ratios.

“Evidence casting doubt on the accuracy of the breath-to-blood conversion ratio is just as relevant as other evidence rebutting the presumption of intoxication from a breath test result, such as evidence that the defendant had a high tolerance for alcohol or performed well in field sobriety testing,” Corrigan wrote.

Jamie L. Popper, the appellate defense lawyer in the case, had this to say:

“The situation currently is that juries are led to believe that when a person blows into the breath test, the blood-alcohol measure that breath test gives is a fact, when all a breath test is is a measure.”

For more on this topic, you can read our previous article on Breathalzyers:
It’s Just A Decimal Point: The Dirty Secret Behind Breathalyzers

And you can read the full Los Angeles Times article here.

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