Mouth Alcohol, GERD, and False High Readings
Texas DWI Defense Attorney
We often think of breathalyzers as sophisticated medical instruments, but in reality, they are small computers making a scientific “guess.” In Texas, the Intoxilyzer 9000 is the standard machine used by police. While it is advanced, it relies on a specific assumption: that the alcohol it measures is coming from deep within your lungs (alveolar air).
At Beltz Law Group, we frequently uncover cases where a “failing” BAC result was caused not by intoxication, but by common medical conditions or procedural errors that created residual mouth alcohol.
1. The Mouth Alcohol Problem
Breathalyzers are designed to measure alcohol that has been absorbed into the blood and then exhaled from the lungs. However, if there is “raw” alcohol sitting in your mouth or throat, the machine will measure that instead. Because mouth alcohol is thousands of times more concentrated than lung air, even a tiny drop can cause a sober person to test at 0.15% or higher.
Common sources of mouth alcohol include:
- Recent Drinking: If you drank shortly before the test, alcohol is still in your mouth tissues.
- Mouthwash or Breath Sprays: Many contain ethanol, which the machine cannot distinguish from beer or whiskey.
- Dental Work: Braces, dentures, or “pockets” in the gums can trap alcohol long after you’ve finished your last drink.
2. The GERD / Acid Reflux Defense
Gastroesophageal Reflux Disease (GERD), acid reflux, and even simple heartburn are among the most powerful defenses against a breath test. These conditions cause stomach contents—including undigested alcohol and gases—to travel back up the esophagus and into the mouth.
When you blow into the machine, these stomach gases mix with your lung air. The Intoxilyzer 9000 “sees” this raw alcohol and produces a falsely high reading. Even if you were below the legal limit, your reflux can make you appear dangerously intoxicated on paper.
3. The 15-Minute Observation Period
DWI Attorney North Texas
To prevent mouth alcohol from ruining a test, Texas law requires officers to follow a strict 15-minute observation period before you blow into the machine. During this time, the officer must ensure you do not:
- Burp or belch
- Vomit or regurgitate
- Put anything in your mouth (gum, water, etc.)
If you burped due to GERD during that 15 minutes and the officer didn’t restart the clock, the test results are legally unreliable. At Beltz Law Group, we meticulously review the “room video” to see if the officer was actually watching you or if they were busy filling out paperwork.
4. Other Factors: Ketosis and Acetone
If you are on a Keto diet, are fasting, or have Diabetes, your body produces chemicals called ketones. One of these, acetone, is chemically similar to isopropyl alcohol. Some older breathalyzers—and even some modern ones under certain conditions—can mistake acetone for ethanol, leading to a “false positive” for alcohol.
How We Challenge the Machine
When we represent a client with a high breath test, we don’t just give up. We:
- Subpoena Maintenance Records: Was the machine calibrated correctly? Has it had frequent “software errors”?
- Analyze the “Slope Detector”: The machine has a built-in sensor to detect mouth alcohol. We check the raw data to see if the machine flagged an “invalid sample” that the officer ignored.
- Present Medical Evidence: We work with your doctors to document your history of GERD or other conditions to show the jury why the machine’s “guess” was wrong.
Do you have a medical condition that might have affected your test? A BAC result is a piece of evidence, not a final verdict. We have the technical expertise to challenge the science and protect your record.
