Certain kinds of evidence seem more conclusive and difficult to fight in court than other kinds of evidence. Many people, including police officers and attorneys, understand that eyewitness testimony could actually be less reliable than security camera footage, for example.

When it comes to allegations of impaired driving, most people consider chemical tests the gold standard for proving impairment. However, chemical tests, particularly mobile Breathalyzer testing, can create many opportunities for user error or unit malfunction.

If you find yourself facing a driving while intoxicated (DWI) charge in Texas, you may feel like fighting back is hopeless, even if you know you weren’t drunk at the time of the traffic stop. The good news is that contrary to what many people believe, it is possible to challenge a chemical breath test in a DWI case.

You know you weren’t drinking or weren’t drunk

When a Breathalyzer test shows that you have an illegal blood alcohol concentration (BAC), the officers who stopped your vehicle will likely arrest you at that time. This kind of encounter can be particularly frustrating if you abstain from consuming alcohol prior to your interaction with law enforcement.

It’s also possible for someone who only had one or two drinks, not nearly enough to leave them drunk, to fail a chemical breath test. When you know the results are inaccurate, that gives you all the more reason to push back against the test and the criminal charges that follow it.

You suspect issues with the testing unit or the police officer who performed the test

Breathalyzers are complex pieces of chemical machinery that analyze exhaled air to look for specific chemical compounds. Many different issues can arise in a testing unit so complex. The units typically require routine calibration and maintenance to ensure proper functioning.

If an officer or department has not performed maintenance and calibrations or if they did not maintain a record of those efforts, challenging the test results may be easier for you. The same is true if the officer or department failed to download and install the most recent software upgrades or patches for the testing device. Finally, it is possible for the officer themselves to make a mistake during the administration of the test that results in a false positive.

You have medical issues that could impact the test results

Chemical breath test units are meant to be compact and portable, as well as easy to use. They are not as accurate as larger gas chromatography/mass spectrometer systems at analyzing chemical samples. Other chemical compounds in the same basic family as alcohol, such as acetone, could create a false positive on a breath test. Uncontrolled diabetes or even a particularly well-adhered-to keto diet could trick certain kinds of breath test units into producing a false-positive result.