Yes, you can challenge DUI breathalyzer results in California. A breath test reading over 0.08 percent blood alcohol concentration does not automatically mean you will be convicted of driving under the influence.

Breath testing devices are not perfect. Police officers can make procedural errors. Medical conditions can skew results. Machines can malfunction. Timing matters. All of these issues can create reasonable doubt in a DUI case.

If you were arrested for DUI in California after blowing over the legal limit, it is critical to have an experienced DUI defense attorney review your case immediately. 

Your best hope for a favorable outcome is with an experienced criminal defense attorney at Eisner Gorin LLP. To schedule a consultation, call (818) 781-1570 or contact us here.

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What Is the Legal BAC Limit in California?

Under California Vehicle Code 23152:

• 0.08 percent BAC is the legal limit for drivers 21 and over

• 0.04 percent BAC applies to commercial drivers

• 0.01 percent BAC applies to drivers under 21

Prosecutors often rely heavily on breath test results to prove impairment. However, a chemical test result is only one piece of evidence in a DUI case.

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How Do DUI Breathalyzers Work?

Breathalyzer machines do not directly measure blood alcohol concentration. Instead, they measure alcohol molecules in deep lung breath and convert that measurement into an estimated blood alcohol level using a mathematical ratio.

This process depends on assumptions about:

• Breath-to-blood partition ratios

• Body temperature

• Lung function

• Machine calibration

If any of these variables are inaccurate, the BAC result may be unreliable.

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Are Breathalyzer Results Always Accurate?

No. Breathalyzers have known error rates.

Even the experts who testify in DUI cases acknowledge that breath testing devices are not 100 percent accurate. In close cases, even a small margin of error can make the difference between guilt and innocence.

If your reading was close to 0.08 percent, the reliability of the machine becomes especially important.

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Common Ways to Challenge DUI Breathalyzer Results

There are multiple legal strategies available to challenge breath test evidence in California DUI cases.

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Machine Calibration and Maintenance Issues

Breath testing devices must be:

• Properly calibrated

• Regularly maintained

• Accurately documented

If maintenance logs reveal improper calibration or skipped inspections, the results may be unreliable.

Your attorney can subpoena maintenance records and challenge the validity of the device.

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Improper Administration by the Officer

Officers must follow strict procedures when administering breath tests.

Common procedural errors include:

• Failing to observe the driver for 15 continuous minutes

• Allowing burping, vomiting, or smoking before the test

• Improper instruction

• Failure to change mouthpieces

Any deviation from protocol can compromise the results.

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Rising Blood Alcohol Defense

BAC levels change over time.

If there was a delay between driving and testing, your BAC may have been lower while you were driving and higher by the time the breath test was administered.

The key legal question is your BAC at the time of driving, not at the time of testing.

This is known as the rising blood alcohol defense.

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Illegal Traffic Stop or Lack of Probable Cause

Police must have:

• Reasonable suspicion to initiate a traffic stop

• Probable cause to arrest

• Lawful justification to administer a breath test

If the stop or arrest was unlawful, your attorney can file a motion to suppress the evidence. If successful, the breath test results may be excluded from court.

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Medical Conditions That Affect Breath Tests

Certain medical conditions can falsely elevate breath test readings, including:

• Gastroesophageal reflux disease (GERD)

• Acid reflux

• Diabetes

• Low-carb or ketogenic diets

• Mouth alcohol contamination

Breathalyzers detect alcohol in breath, not directly in blood. Mouth alcohol or residual alcohol can distort results.

Medical documentation and expert testimony can help challenge inflated readings.

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Partition Ratio Variability

Breath machines assume a standard breath-to-blood alcohol ratio. However, this ratio varies among individuals.

Differences in:

• Body composition

• Temperature

• Hematocrit levels

• Breathing patterns

can affect the estimated BAC reading.

This scientific variability can create reasonable doubt.

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Refusing a Breath Test in California

California is an implied consent state. If you refuse a chemical test after lawful arrest, you may face:

• Automatic license suspension

• Enhanced DUI penalties

• Additional DMV consequences

However, even if you submitted to a breath test, the results can still be challenged in court.

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DMV Administrative Per Se Hearing

After a DUI arrest, you have only 10 days to request a DMV hearing to challenge your license suspension.

At this hearing, your attorney can challenge:

• The legality of the stop

• The validity of the arrest

• The reliability of the breath test

Winning at the DMV hearing can preserve your driving privileges.

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Can You Beat a DUI If You Blew Over 0.08?

Yes. A breath test reading above 0.08 does not guarantee conviction.

Successful outcomes often depend on:

• Quality of legal representation

• Scientific review of the evidence

• Officer credibility

• Procedural compliance

• Strength of prosecution evidence

Many DUI cases are reduced or dismissed when weaknesses are exposed.

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Frequently Asked Questions

Is a breathalyzer enough to convict me of DUI?

Not by itself. The prosecution must prove impairment or unlawful BAC beyond a reasonable doubt.

Can a breath test be wrong?

Yes. Breath tests have error rates and are affected by calibration, operator error, and medical factors.

What if my BAC was just over 0.08?

Close cases are often the strongest for defense. Margin-of-error arguments can be powerful.

Should I get a lawyer even if I failed the breath test?

Yes. Breath test results are frequently challenged successfully.

What if I refused the test?

You may face license consequences, but refusal cases also present defense opportunities.

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Why Legal Representation Is Critical in DUI Cases

Prosecutors rely heavily on breath test numbers to pressure defendants into plea deals. Without skilled legal analysis, errors in testing procedures or machine maintenance may go undiscovered.

An experienced DUI defense attorney can:

• Subpoena calibration records

• Challenge officer conduct

• File suppression motions

• Retain expert witnesses

• Negotiate reduced charges

• Fight the case at trial

Early intervention is key.

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Speak With a California DUI Defense Attorney

If you were arrested for DUI after taking a breath test, do not assume your case is hopeless. Breathalyzer results can be challenged, and many DUI cases are successfully defended.

A thorough review of the stop, arrest procedures, and testing process may reveal critical weaknesses in the prosecution's case.

Contact an experienced California DUI defense attorney immediately to protect your license, your record, and your future.

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