Defense Attorneys Can Challenge Breath Tests Under New Court Ruling

A recent California Supreme Court ruling from a case in San Bernardino County allows for DUI defense attorneys to challenge the results of a breathalyzer test.

What had been banned by the courts since the early 1990s, DUI defense attorneys in California can now raise a "partition ratio" defense in cases where the defendant failed a breath test.

The current state standard for breathalyzer machines is a 2,100 to 1 partition ratio, which means the amount of alcohol in 2,100 milliliters of breath is considered equal to the amount of alcohol in 1 milliliter of blood.  

In a sense, the ruling acknowledges that ratios can differ widely, depending on the defendant.  Defense attorneys can now argue that a defendant's weight, stomach content at the time of arrest, and overall health can affect the accuracy of a breath test.

Naturally, the new ruling is met with opposition from prosecutors and support from defense attorneys.

"The truth is a breath machine reading is an estimation, not an exact measurement," said Darryl W. Genis, a DUI defense lawyer in Santa Barbara. "If the machine was that right, you would just blow into it and it would turn out a fine and probation at the same time as the blood-alcohol reading. They are not that reliable."

Mark A. Vos, a prosecutor in San Bernardino County, feels the partition ratio defense is "logically irrelevant," asking how defendants could possibly know or re-create all of the conditions at the time of arrest, which is needed to prove the breath test was wrong.

For more information about the recent ruling in California, click here to find a DUI attorney near you.