Under California Vehicle Code 23152 VC, it is illegal to operate a motor vehicle while under the influence of alcohol. Specifically, driving with a blood alcohol concentration (BAC) of 0.08 percent or higher creates a legal presumption of driving under the influence.
In Los Angeles County and throughout Southern California, thousands of DUI cases are filed annually, with the prosecution's case relying heavily on chemical breath test results.
However, breathalyzer readings are not infallible. Breath testing devices do not measure blood alcohol directly; instead, they analyze breath samples and apply a generalized mathematical conversion ratio to estimate BAC levels.
Machine maintenance flaws, physiological factors, and procedural errors frequently compromise these results, giving skilled defense attorneys an opening to build a strong challenge.
Why Can Breathalyzer Results Be Challenged in Court?
Breath testing devices possess documented error margins and rely on assumptions that do not apply uniformly to every individual.
In borderline DUI cases—such as a reading of 0.08 or 0.09 percent—even a minimal margin of error can create reasonable doubt regarding actual impairment.
Defense strategies often focus on attacking the test's core reliability through machine maintenance logs, calibration records, and operator certification histories.
What Common Factors Invalidate Breathalyzer Tests?
Several distinct physiological, technical, and procedural vulnerabilities can undermine the validity of a chemical breath test:
|
Vulnerability Type |
Description & Scientific Factor |
Impact on DUI Case |
| Rising Blood Alcohol | Alcohol continues to be absorbed into the bloodstream after driving stops, meaning a driver's BAC may have been legal while driving but rose by test time. | Creates a valid "rising blood alcohol" defense challenging BAC levels at the exact time of operation. |
| Procedural Errors | Officers must strictly observe the subject for a continuous 15-minute observation period before testing to prevent mouth alcohol contamination. | Failure to follow strict Title 17 operational protocols can completely invalidate breath test results. |
| Medical Conditions | Physiological conditions such as acid reflux (GERD), diabetes, ketogenic diets, or dental work can trap alcohol and inflate readings. | Contaminates breath samples by introducing residual mouth alcohol rather than deep-lung air. |
Frequently Asked Questions (FAQs)
Can you beat a DUI charge in California if your breath test result was over 0.08?
Yes. Breathalyzer results are not bulletproof. An experienced attorney can successfully challenge chemical test results based on machine calibration errors, rising blood alcohol levels, improper officer administration, or constitutional violations during the traffic stop.
Are breathalyzers completely accurate?
No. Breath testing devices have inherent error margins and rely on generalized partition ratios to estimate blood alcohol. These baseline assumptions do not account for unique biological differences across individual drivers.
What is the rising blood alcohol defense?
The prosecution must prove your BAC was 0.08 or higher while you were actively driving, not hours later at the police station. If your body was still absorbing alcohol during or shortly after the drive, your BAC may have been legal behind the wheel.
Can medical conditions cause a false positive on a breathalyzer?
Yes. Conditions such as gastroesophageal reflux disease (GERD), acid reflux, severe heartburn, diabetes, and low-carbohydrate diets can introduce mouth alcohol or chemical compounds that artificially inflate breath test readings.
What happens if I refuse to take a breath test after a DUI arrest?
California operates under an "implied consent" law, meaning driving implies agreement to chemical testing upon a lawful arrest. Refusing a test typically results in an automatic administrative driver's license suspension, though the underlying arrest and traffic stop can still be legally challenged.
How can a criminal defense lawyer help challenge a DUI breath test?
A defense attorney can subpoena machine maintenance and calibration records, review bodycam and dashcam footage for procedural errors, consult with forensic toxicology experts, and file motions to suppress unlawfully obtained evidence.
The California criminal defense attorneys at Cron, Israels & Stark are here to help you. Schedule a consultation through the contact form or call us at (424) 372-3112. We are located in Los Angeles, CA.
