Driving under the influence (DUI) is a serious charge that can lead to significant legal and personal consequences, including fines, license suspension, increased insurance premiums, and even jail time. However, not every DUI arrest results in a conviction. One potential defense that may apply in certain cases is the “mouth alcohol” defense. But what is mouth alcohol, and can it really help get your DUI case dismissed?
In this article, we’ll explore what mouth alcohol is, how it affects breathalyzer results, and whether it can be a successful defense strategy in court.
What Is “Mouth Alcohol”?
“Mouth alcohol” refers to the presence of residual alcohol in the mouth or upper respiratory tract that can cause artificially high readings on a breathalyzer test. Breathalyzers are designed to measure the alcohol content in a person’s deep lung air—not the mouth or throat. However, if alcohol is lingering in the mouth for any reason, it can contaminate the breath sample and lead to a falsely elevated blood alcohol concentration (BAC) reading.
Common Causes of Mouth Alcohol:
Recent alcohol consumption (even a sip)
Use of mouthwash or breath sprays containing alcohol
Belching, burping, or acid reflux shortly before testing
Dental work or dentures that trap small amounts of alcohol
Vomiting or regurgitation
Because the breathalyzer assumes the alcohol is coming from deep lung air, any mouth alcohol present during the test can result in an inaccurate BAC reading.
Why Breathalyzer Accuracy Matters in DUI Cases
In most DUI arrests, the breathalyzer test is a cornerstone of the prosecution’s evidence. In many jurisdictions, a BAC reading of 0.08% or higher is considered per se evidence of intoxication. That means if the breath test shows you were at or above the legal limit, it can be enough to convict you—unless you successfully challenge the accuracy of the test.
If the reading was skewed due to mouth alcohol, it could lead to:
False positives
Unjustified arrest
Improper prosecution
Therefore, identifying and proving the influence of mouth alcohol can potentially invalidate the breath test result, undermining the prosecution’s case.
How Does the Mouth Alcohol Defense Work?
The mouth alcohol defense is based on the argument that your breathalyzer test result was artificially inflated due to residual alcohol in your mouth or throat, rather than alcohol absorbed into your bloodstream.
To use this defense effectively, your attorney may:
Challenge the reliability of the breathalyzer reading
Introduce evidence that you used mouthwash or other alcohol-based products
Prove that you burped, vomited, or had acid reflux shortly before the test
Question the observation period conducted by the arresting officer
Observation Period: Why It Matters
In many states, law enforcement is required to observe a DUI suspect for 15 to 20 minutes before administering a breath test. During this observation period:
The officer must ensure the suspect does not eat, drink, burp, vomit, or smoke
If any of those events occur, the observation period should restart
Why? Because actions like burping or vomiting can bring alcohol from the stomach into the mouth, contaminating the breath sample.
If the observation period wasn’t properly followed, a skilled DUI lawyer can argue that the test result is unreliable due to possible mouth alcohol contamination.
Scientific Backing of the Mouth Alcohol Defense
Several studies and expert testimonies have shown that breathalyzer results can be influenced by mouth alcohol. Breath testing devices use infrared spectroscopy or fuel cell sensors to detect ethanol, but they generally cannot distinguish between deep lung air and residual alcohol in the mouth.
While modern breathalyzers are designed with safeguards like “slope detectors” to identify mouth alcohol, they are not foolproof. False positives can and do occur, especially in borderline BAC cases (e.g., 0.08% or 0.09%).
Scenarios Where Mouth Alcohol Can Apply
1. Use of Mouthwash or Breath Spray
Imagine someone uses a mouthwash that contains alcohol just minutes before getting pulled over. Even if their actual BAC is well below the legal limit, the mouthwash residue could produce a high reading.
2. Gastroesophageal Reflux Disease (GERD)
People with GERD or acid reflux may experience regurgitation of stomach contents, including alcohol, which can linger in the mouth and affect breath test results.
3. Recent Drinking
If someone had just taken a final drink seconds before being pulled over, their BAC may not have peaked yet. However, mouth alcohol from the last sip could still influence the breathalyzer reading.
Can This Defense Really Get a DUI Case Dismissed?
Yes, it can, but not in every case. The mouth alcohol defense is fact-specific and typically works best when:
The BAC reading was only slightly above the legal limit
There is evidence of mouth alcohol contamination
The officer failed to observe proper testing procedures
You have a medical condition (e.g., GERD) that supports the claim
It’s important to understand that merely claiming mouth alcohol is not enough. The defense must be substantiated with evidence, and the burden is often on your legal team to introduce reasonable doubt.
Supporting Evidence That Strengthens the Defense
To improve the chances of success, your attorney may present:
Surveillance footage showing improper testing procedures
Medical records of acid reflux or dental issues
Expert testimony on breathalyzer inaccuracies
Witness statements confirming you used mouthwash or vomited
Maintenance logs for the breathalyzer device (to check calibration)
Legal Precedents and Court Views
Some courts have acknowledged the potential for mouth alcohol to affect test results. In such cases, DUI charges have been reduced or dismissed when:
The test results were borderline
The mouth alcohol defense was credible and well-supported
The officer failed to follow proper testing protocols
However, in other cases—particularly where BAC levels were significantly above the legal limit—courts have been less receptive to this defense.
Limitations of the Mouth Alcohol Defense
While it’s a valid defense, it’s not a silver bullet. Some limitations include:
No effect on blood tests (which are more accurate)
Less effective if BAC was well above 0.08%
Not applicable if proper waiting period was followed
Must be corroborated with evidence or expert testimony
Conclusion
The mouth alcohol defense can be a powerful tool in a DUI case—but only under the right circumstances. If you believe your breath test result was influenced by mouthwash, belching, acid reflux, or recent drinking, it’s crucial to speak with an experienced DUI attorney who can evaluate whether this defense applies to your case.
A successful challenge to the breathalyzer could lead to:
Suppression of the breath test evidence
Reduction of charges
Possible case dismissal
However, each DUI case is unique, and the success of the mouth alcohol defense depends heavily on the specific facts and the quality of legal representation. If you’re facing DUI charges, don’t leave your future to chance—consult with a legal professional to explore your best defense options. Contact Southwest Legal today for a free consultation and start building a strong defense.
FAQs
Q: Can chewing gum or breath mints affect a breathalyzer test?
A: Generally, no—unless they contain alcohol. Most standard gums or mints are safe, but alcohol-based sprays or mouthwashes can cause issues.
Q: Is it better to refuse a breath test if I’ve used mouthwash?
A: Refusing a breath test can have legal consequences, including automatic license suspension in many states. Always consult a lawyer about your rights in your specific jurisdiction.
Q: Will a blood test eliminate the mouth alcohol issue?
A: Yes. Blood tests are not affected by residual mouth alcohol and are considered more accurate for determining actual BAC.
