Yes, residual mouth alcohol is a defense that can get your Nevada DUI charges dismissed. Mouth alcohol can cause breathalyzers to return inaccurately high blood alcohol content (BAC) readings even if your actual BAC is legal (at or below 0.08%).1
Mouth Alcohol Definition
Like it sounds, mouth alcohol is traces of alcohol in your mouth’s mucosal linings. You get mouth alcohol from various sources, such as:
- Drinking alcoholic beverages, such as wine, spirits, liquor, or beer
- Medicines such as certain cough syrups – such as Nyquil
- Mouthwashes or breath sprays like Listerine
- Chewing tobacco
- Dentures, retainers, or other dental work that may cause alcohol to get trapped and pool
- Such medical conditions as GERD (gastroesophageal reflux disease), acid reflux, and heartburn2
I have defended many clients who never drink alcohol but who were wrongly arrested for DUI because they used Listerine that day or were suffering from acid reflux. I raised a “reasonable doubt” as to their guilt and got their charges dropped by showing the D.A. relevant receipts, medical records, and eyewitness testimonies.
How Mouth Alcohol Affects BAC Readings
Breathalyzers test your breath sample, not blood sample. So if you have residual mouth alcohol from any of the above-mentioned sources, it may cause your breath test to return results that are not reflective of your blood alcohol content.
Nevada DUI laws only prohibit driving with a high BAC level. It does not matter what your mouth alcohol content is.
Example: Emily takes one sip of wine at a dinner party and drives home. A policeman pulls her over because of a broken tail light. The officer smells the wine on Emily’s breath and performs a breathalyzer test. If traces of the wine are still in Emily’s mouth, it could cause a high breath test result even though her actual BAC is surely legal since she drank such a small amount of alcohol. Emily’s defense attorney could raise the mouth alcohol defense in her case.
In short, it is possible that your mouth alcohol may cause a high BAC reading on a breath testing machine when in fact you have a perfectly legal blood alcohol content. Breathalyzers do not always distinguish between deep lung air (alveolar air) and mouth air, which contains mouth alcohol.3
How Police Try to Avoid Inaccurate Breathalyzer Tests
If you get arrested for drunk driving in Nevada, police officers must observe you for 15 minutes before administering the evidentiary breathalyzer test (unless you elect to take a blood test instead). The purpose of this observation period is to give any mouth alcohol the chance to dissipate.
The officer also makes sure you are not:
- burping,
- vomiting, or
- putting anything in your mouth.
In my experience though, law enforcement officers often miss it when you burp (causing some alcohol to reflux). Any regurgitation will likely cause a falsely high blood alcohol concentration reading on your breathalyzer chemical test.4
In these cases, I rely on the police’s bodycam footage to show that the officers failed to adequately observe you and therefore failed to obtain an accurate breathalyzer reading.
Mouth alcohol can cause inaccurate breathalyzer results.
Additional Reading
For more information about Nevada DUI laws, refer to our related articles:
- Nevada DUI: Should I choose a breath test or a blood test? – a side-by-side comparison of the pros and cons of each chemical test
- The court process in Nevada DUI cases – a step-by-step look at how drunk/drugged driving cases proceed through criminal court
- Top 20 defenses to a Las Vegas Nevada DUI charge – overview of the most common ways to fight DUI charges
- I was suffering from hypoglycemia when I was arrested for DUI in Nevada. Can I use this to fight the charges? – a deep-drive into how diabetes can affect breath test results
- Do I have to admit that I’ve been drinking if I’m pulled over for DUI in Nevada? – a discussion of how you should be polite to police but not answer any questions
Legal References
- NRS 484C.110. C.D. Simpson, “Effects of Mouth Alcohol on Breath Alcohol Results,” Western Michigan University (Feb 25, 2016). K. Sterling, “The rate of dissipation of mouth alcohol in alcohol positive subjects,” J Forensic Sci (2012).
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- DWI Detection and Standardized Field Sobriety Testing (SFST), Participant Manual, Table of Contents, NHTSA (2015).