Texas is very tough when it comes to DUIs and DWIs in Austin, and individuals can face serious consequences for driving while intoxicated. Indeed, under Texas law, you can face stiff monetary penalties in addition to jail time for a DWI conviction. As such, when you have been charged with a DWI in Austin, it is important to consider any and all defense that can help you to beat that DWI. One possible defense is arguing that you had residual mouth alcohol at the time the breathalyzer test was administered.

What is Mouth Alcohol?

Since mouth alcohol can be a successful defense to an Austin, TX DWI case, it is important to understand more about what it is and why it leads to false positives in breath tests.

According to a module from Duke University, breathalyzer tests work by assuming that “alcohol in the blood is in equilibrium with alcohol in the expired air.” What does that mean? In short, when you drink alcohol, you have a higher concentration of alcohol in your blood than in your alveoli, which are the small air sacs in your lungs. After you drink alcohol, the ethanol diffuses into the alveoli, resulting in—in theory—an equilibrium of alcohol concentration in your blood and in your breath.

There are numerous things that can disrupt this equilibrium, and as the module clarifies, the “validity of a Breathalyzer test is dependent on the equilibrium of ethanol in the blood and the alveolar air.”

Exhaled Air Can Show a False FAC Reading

Here is where the issue of residual mouth alcohol comes into play as a potential defense for a DWI in Austin, Texas. Rather than reading the BAC of your alveolar air, the breathalyzer or other breath test being used captures the alcohol content in the air you exhale. This exhaled air is supposed to provide an accurate reading of the BAC of both your alveolar air and your blood, but there are numerous factors that can affect the perceived alcohol content of your breath.

When a breath test shows that your BAC is higher than it actually is, you may be able to prove that mouth alcohol resulted in this faulty breathalyzer reading. Mouth alcohol can result from many different circumstances, including but not limited to:

Getting a DWU Attorney in Austin

Mouth alcohol residue can lead to incorrect breathalyzer test results. When this happens, the individual who has been charged with a DUI/DWI may be able to have the case dismissed.