California Supreme Court Agrees Breath Test Accuracy Can Vary

High court questions accuracy of breath test equipment used in CA DUI arrests.

On Thursday the California Supreme Court unanimously ruled that breath test results can vary between people. The finding bolsters claims by DUI defense attorneys that breathalyzers may not accurately detect the percentage of alcohol in a motorist’s blood system and result in a false arrest for driving under the influence. A handful of courts across the country have made rulings similar to that of the California high court.

Alcohol is carried through the blood stream to the brain, liver and heart before being diffused in the lungs. A breathalyzer is intended to analyze exhaled breath and determine if a driver has a blood-alcohol content above the legal limit for intoxication. The problem is that the source code assumes one model for a body’s ability to process alcohol and uses a straight line of assumptions to determine BAC. In actuality, it has become increasingly recognized that body temperature, atmospheric pressure, medical conditions as well as the calibration of the device can create a wide fluctuation in results.

In California, a DUI can be charged two ways: when a motorist exhibits obvious signs of intoxication, like blood-shot eyes, slurred speech and a lack of stability; or when a test for blood alcohol content registers .08% or higher. In the latter case, the threshold is considered definitive for intoxication even though the driver may show no signs of impairment.

The application of penalties for drunk driving is rarely graduated based on level of blood alcohol content and a motorist typically faces severe financial, legal and social difficulties by being found guilty of driving under the influence. The fact that a motorist may be prosecuted based on a false reading is one of the concerns being addressed by the courts. By law, a defendant has the right to challenge an accusation of a crime, though until recent court rulings, the workings of the equipment and the nature of the source code were held as trade secrets by the manufacturer.

The high court justices believe entering evidence of the variability of test results to the jury does not remove the presumption of intoxication. Prosecutors accept that more breath test evidence will be challenged in California DUI cases, but agree that there often is additional evidence to warrant a conviction for drunk driving.

DUI defense lawyers are pleased with the ability to raise the question of the accuracy of breath tests and the court’s acceptance that one-size does not fit all.

Did you recently take a breath test and were arrested for DUI in CA?