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How Reliable Are Breathalyzer Tests?

From the “Drunkometer” used in the 1930s to today’s Breathalyzer, blood alcohol concentration (BAC) tests have made it very easy for police to charge Texas citizens with drunk driving. But are these tests always 100 percent correct in measuring a person’s level of intoxication? The answer is “no,” because many factors can affect a reading.


Down the Hatch

First, a general overview of what alcohol does once it’s in the body: Ethanol is a miniscule molecule that readily passes through bodily tissues. Once consumed, it goes through the walls of your small intestine and stomach and into your blood. Your body warmth helps it become vaporized through your lungs when you breathe. The faster and more you drink, the more you exhale. (It also oozes through the skin if the body can’t process it quickly enough, giving an over-indulger an alcohol scent.)


How a Breathalyzer Works and What Can Go Wrong

While home-use breathalyzers tend to use semiconductors, professional-grade ones often use fuel-cell technology. The object is to only collect deep-lung breath where alcohol concentration is greatest. The subject is given instructions on how to blow and for how long. The test administrator has to ensure that the breath is not emanating only from the subject’s mouth.

Anything from test equipment, waiting period, length of test, what the blower has consumed, and more can compromise results. Even being around other chemicals can move the needle up or down. These are just a few examples:

How the Test Was Administered

Did the arresting officer properly follow protocol? Were they properly trained or retrained?

Where You Work and Where You’ve Been

If your workplace contains acetone, that can skew the reading. Plastics, varnish, adhesives, and other chemical compounds can cause fluctuations as well.

The Condition of the Breathalyzer

Has the device been calibrated and cleaned? Using alcohol to sterilize the device can affect the next outcome. Were the batteries and software in working order?

Health Conditions

Heartburn, acid reflux, burping, vomiting, GERD, diabetes, and more can all affect how much alcohol readings are enhanced or whether excess alcohol is churned into the mouth rather than emanating from the deep lung tissue.

Trapped Alcohol

Excess alcohol can be trapped in the mouth by gum, dental work, mouthwashes, and toothache medicine or on the other end, by a previously used intoxilyzer mouthpiece. Throwing up can bring more alcohol into the mouth, which would provide a stronger reading than just fumes.

Other Actions of Law Enforcement

Why were you pulled over and was it in keeping with implied consent laws? “Implied consent” allows Texas law enforcement officials to give you a test if they suspect that you are drunk. If you refuse, you receive an automatic 180-day license suspension—unless you are a repeat offender, in which case it is a two-year suspension.


Austin and Wilco DWI Defense Lawyers

Even being accused of drunk driving can have lasting deleterious effects. This article details how, along with providing details on the increasing skepticism about these tests. It also mentions how hundreds of cases are thrown out each year due to faulty results.

No matter the charges, Tillman Braniff, PLLC will fight to protect you from unnecessary hardship caused by false accusations and over-zealous penalties. We’d be happy to hear about the charges you’re facing and tell you how we can help. Call today for a free and confidential case evaluation by calling 512-472-6565 for Austin residents or 512-473-8745 for Wilco residents. You can also reach us through the online contact form on this page.

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