How Do You Challenge a Breath Test in a Texas DWI Case?

 Posted on June 19, 2025 in DWI

Being stopped, arrested, and charged with driving while intoxicated (DWI) is unnerving. You were likely confronted with requests for field sobriety testing and DWI breath tests. Most people in this type of situation are not sure what to do in the heat of the moment. Regardless of how the arrest went down or whether you failed a blood alcohol concentration (BAC) breath test, you should reach out to our experienced Prosper, TX DWI defense lawyers right away. Understanding the problems with BAC testing and how we challenge the results in court is important.

Understanding BAC Testing in Texas DWI Cases

Texas law enforcement commonly uses breath tests to check blood alcohol levels when they have probable cause to arrest someone for DWI. The state laws regarding DWI stipulate that the legal limit for drivers over the age of 21 is 0.08 percent, and the results of a BAC breath test can be used as evidence of DWI in court.

If you are concerned that you made a mistake by submitting to a breath test after your arrest, understand that – according to Texas's implied consent law – you had no choice. If the police had probable cause to arrest you under suspicion of DWI, the law requires you to take the breath test, and the officer who arrested you should have informed you of that law. For the prosecution to use your BAC breath test as evidence, they must show that the police followed protocol when administering it. Any deviation from standard procedure is a reason to challenge their use of the test results as evidence.

Common Problems With BAC Breath Tests

The breath test itself can also be challenged. Your attorney will look for factors that could impact the test’s accuracy. For example, the machines used for breath tests have to be regularly calibrated, and maintenance records can show if the machine was well-maintained. Outside elements can impact the reliability of the test results as well. For instance, substances like certain medications and mouthwash can leave alcohol residue in the mouth that can produce a false BAC reading. The same is true for certain medical conditions, like acid reflux, asthma, and diabetes.

Legal Defenses To Challenge BAC Test Results in Texas

Common legal defenses employed to challenge BAC breath tests in Texas DWI cases include:

• Rights violations: If the officer did not have probable cause to pull you over or conduct the breath test, you can argue that they violated your Fourth Amendment rights, potentially resulting in the suppression of evidence against you.

• Missing informed consent: If the officers did not inform you of the consequences of refusing a breath test before they administered it, you can argue that you did not give informed consent.

• Invalid administration: If any procedural errors occurred in administering the test or in the chain of custody, the results may be excluded as evidence.

When you talk to your attorney about the details of your case, you can work together to figure out the right strategy for your defense.

Contact a Prosper, TX DWI Defense Attorney for a Free Consultation

If you are facing DWI charges and have concerns about BAC test results being used in your case, the Collin County, TX DWI defense lawyers at Law Offices of Biederman & Burleson P.L.L.C. can help. We have over 25 years of combined experience and more than 500 trial victories for DWI cases. Call us today at 469-333-3333 to schedule your free consultation and learn more about the strategies we can employ to challenge BAC test results and the charges against you.