Orange County DUI Defense Lawyers can Challenge Breathalzyers

It used to be in California that a DUI defendant had little recourse in certain cases where a breathalyzer test had offered up a blood-alcohol content measurement of 0.08 percent or higher.

However, our Rancho Cucamonga DUI defense lawyers know that a 2009 state supreme court decision, People v. McNeal, changed the playing field. It resulted in allowing evidence showing the test could be influenced by factors that might vary from person-to-person. Specifically, it allowed challenges to the scientific formula known as “Henry’s Law.”

It’s been four years since that decision. A number of other states have followed suit, most recently in Arizona. There, the high court has just ruled that defendants should have the right to present evidence to jurors showing that factors such as body temperature may impact the validity of the test results.

Decisions like these have begun to crack the facade of these tests as somehow being infallible. It’s difficult to understand how they even attained such status to begin with.

Henry’s law, first introduced in the 1800s, is a formula used by the machines to convert the amount of alcohol vapor in the lungs to a set blood-alcohol level. But here is the problem: breath-to-blood ratios vary tremendously from person to person. They can be influenced by not only body temperature, but atmospheric pressure, medical conditions and even the precision of the measuring device, sometimes called the calibration.

That means that two people who in fact are about the same in terms of levels of intoxication might measure differently on the test. This inherent unfairness was well-known by defense lawyers, but we were in many states – including California – barred from challenging the device.

Making matters more complex, specifically in California, is the fact that we have two DUI laws. The first, which has been on the books for many, many years, holds that proof of intoxication means showing clear, observatory proof. For example, were the defendant’s eyes bloodshot? Did he or she have trouble concentrating or speaking? Were they unsteady on their feet? Did they display erratic driving patterns behind the wheel?

The second law, which was first passed in 1981 and amended eight years later, held that someone with a blood-alcohol level measuring 0.08 percent could be considered drunk, regardless of his or her behavior or appearance. In 1994, the California Supreme Court ruled that the 0.08 percent blood-alcohol reading included breathzlyer results, where it had previously only included actual blood tests. That ruling specifically banned defense lawyers from attacking the breathalyzer.

Then came People v. McNeal. In this case, the defendant was charged with both DUI violations, as is common for prosecutors hoping to bolster their chances at a conviction. The jury convicted him on one count, but hung on the other.

The defendant moved for a new trial, arguing he should receive a new trial due to the fact that he was not allowed to introduce evidence showing that the machines were faulty. When that effort failed, he appealed – all the way to the state supreme court.

Both the appellate court and the state supreme court held that while evidence of the breathzlyer machine’s infallibility should have been introduced in court, the error in McNeal’s case was harmless because there was ample other evidence to convict him.

However, the ruling opened the doors for others to challenge those tests – which is good news for you if you’re facing California DUI charges.

Contact Houman Fakhimi trial attorney at (714) 705-6701 as soon as possible if you are arrested in Rancho Cucamonga.

Additional Resources

California Supreme Court holds that partition ratio evidence is admissible to challenge charge of driving under the influence, Aug. 16, 2013, By William K. Kirk, National College for DUI Defense.