Breathalyzer & BAC Defense in Illinois

The Breathalyzer Is Not Infallible

Many people believe that "blowing over" means their case is hopeless. That's simply not true. Breathalyzer results are evidence—but evidence can be challenged, questioned, and sometimes thrown out entirely.

After 25+ years defending DUI cases exclusively—nothing but DUI—Andy has seen countless breath test results successfully challenged. These machines have limitations, and the procedures for using them have strict requirements. As a State Delegate to the National College for DUI Defense, Andy stays current on the latest scientific research into breath testing accuracy and defense strategies.

In DuPage County, the machines used at the Wheaton courthouse and local police departments must meet specific Illinois State Police calibration standards. Maintenance logs, operator certifications, and testing procedures all present potential defense opportunities that an experienced DUI attorney knows how to exploit.

Ways to Challenge Breathalyzer Evidence

• Calibration Issues: Breathalyzers require regular calibration to be accurate. Maintenance records must show proper calibration—if they don't, the results are questionable.
• Operator Certification: The officer administering the test must be properly trained and certified. Lapsed certification can invalidate results.
• Observation Period: Officers must observe you for 15-20 minutes before testing to ensure nothing affects the test. Failures here create defense opportunities.
• Rising Blood Alcohol: Your BAC continues rising 30-90 minutes after your last drink. You may have been under .08 while driving even if you tested over .08 later.
• Medical Conditions: GERD, diabetes, and certain conditions can produce false high readings.
• Mouth Alcohol: Recent belching, vomiting, or even certain mouthwashes can contaminate breath samples.

The Rising Blood Alcohol Defense

Here's how it works: You finish your last drink and start driving home. Your BAC is still rising as alcohol absorbs into your bloodstream. You get pulled over 20 minutes later. By the time you're tested at the station—maybe an hour after driving—your BAC has risen above .08.

The question isn't what your BAC was when tested. It's what your BAC was when you were actually driving. If you were under .08 while driving, you're not guilty—regardless of what the test showed later.

Medical Conditions That Affect Results

• GERD/Acid Reflux: Can bring stomach alcohol into the mouth, causing falsely high readings
• Diabetes: Can produce acetone that breathalyzers may read as alcohol
• Ketogenic Diets: Produce ketones that can affect breath test accuracy
• Dental Work: Can trap alcohol in the mouth, affecting readings

If you have any of these conditions, tell your attorney immediately—it may be crucial to your defense.

What Andy Investigates

For every DUI case involving breath tests, Andy examines:

• Machine calibration and maintenance records
• Operator certification and training
• Observation period compliance
• Timeline from last drink to driving to testing
• Medical history and conditions
• Test administration procedures

This investigation often reveals problems the prosecution hasn't considered. When the breathalyzer evidence is weakened or excluded, the case may be dismissed entirely or result in a favorable plea negotiation.

If your case also involved field sobriety tests, those results can be challenged simultaneously—creating multiple points of attack on the prosecution's evidence.

For professionals whose careers depend on the outcome—doctors, nurses, financial advisors, attorneys, commercial drivers—the stakes of a breath test challenge are even higher. A conviction based on questionable breathalyzer evidence can trigger licensing board action that affects your entire career. Learn about professional license protection.

Related Topics: How to Beat a DUI • Field Sobriety Test Defense • Getting Charges Dismissed • First DUI in Illinois • License Suspension & 90-Day Deadline • Professional License Defense • Service Areas