Can You Challenge Breathalyzer Test Results?

 Posted on February 06, 2025 in Criminal Defense

In most cases where a driver is suspected of driving under the influence (DUI), the police officers will pull him or her over and perform a breathalyzer test. In Illinois, as with most of the country, the legal limit is .08 percent, and if a driver gets a higher result, it generally leads to DUI charges. However, over the years, the machines used to perform the breathalyzer tests have been found faulty in many ways, and their results are sometimes considered unreliable. If you are facing DUI charges, speak with an experienced Illinois criminal defense lawyer about options for getting them dismissed.

Common Strategies for Challenging Breathalyzer Tests

There are several reasons why the results of a breathalyzer test can be challenged. They typically fall under one of the following categories: issues with the machine, issues with the machine operator, or issues with the test subject:

Breathalyzer Machine Issues

The machine used for conducting breathalyzers tests how much alcohol a driver exhales to calculate a blood alcohol concentration (BAC) level that represents the percentage of alcohol in the bloodstream. Most people assume this is a reliable and straightforward scientific test. You might be surprised to learn that comparisons of breathalyzer results and actual blood tests have indicated that there can be a 50 percent margin of error.

Breathalyzer Operator Issues

Anyone who operates a breathalyzer machine needs training in how to use it and how to properly administer the test. Part of this training includes the fact that a test subject needs to be monitored for twenty minutes before the test can be administered, which is sometimes overlooked during field sobriety tests. 

Test Subject Issues

A breathalyzer can be inaccurate because of issues impacting the test subject, including:

• Legal medications the subject has taken, for example, cough syrup or asthma medicine, which can lead to a higher BAC level than the person actually has.

• Medical conditions the subject has, such as diabetes, COPD, GERDS, or another type of respiratory illness.

• The test subject’s work involved exposure to paint, gasoline, dry cleaning material, or another source of fumes.

• The test subject is on a low-carb diet, and acetone that is, therefore, on his breath is mistakenly read as alcohol by the breathalyzer.

• The test subject is nervous and is sweating and/or hyperventilating, which can confuse the machine.

Schedule a Free Consultation with a Naperville, IL Criminal Defense Attorney

If you are facing drunk driving charges, speak with a skilled Naperville, IL DUI lawyer as soon as possible to give yourself your best chance at fighting the charges. At Law Office of Philip R. Nathe, we understand how distressing it can be to face criminal charges and we are dedicated to building you a strong defense for your best outcome. Call 630-416-7600 for a free consultation.