One of the defenses against a DUI charge is that of residual mouth alcohol. This defense is based on the fact that there are traces of alcohol in the mouth, which the breathalyzer picks up, instead of alcohol from the deep lung tissue. This results in a false high reading by the DUI breath test devices.
Though the alcohol hasn’t entered the bloodstream yet (and thus, you are not under the influence), the DUI breath test will detect it and report a falsely high BAC (blood alcohol concentration).
This can create confusion, and you can be charged with crimes relating to alcohol, such as driving under the influence, driving with a BAC equal to or higher than 0.08%, or an underage DUI.
Of course, you don’t want this. So, the mouth alcohol defense can be effective in some cases.
What Is Mouth Alcohol?
Residual mouth alcohol, as the name suggests, is when traces of alcohol remain in the mouth. This can be because the individual has consumed or regurgitated anything that contains alcohol. Traces of alcohol in the mouth could be from anything, including alcoholic beverages, medicines like cough syrup, mouthwash, and some breath sprays.
Mouth alcohol can also be created due to medical conditions like acid reflux and dental devices that trap and gradually release the food and liquid you consume.
In such cases, even though you are not under the influence, your mouth has traces of alcohol, which can lead to false positives and a false DUI charge.
How Does Mouth Alcohol Lead to a Higher BAC Reading?
When you consume anything that contains alcohol, a small amount stays in your mouth. It gets caught in the mucosal lining of your mouth, which is the soft tissue on the inside. Though it doesn’t take long for this remaining alcohol to get washed away, it takes longer to go through your digestive system and enter the bloodstream.
Therefore, when you consume or use anything that has alcohol in it, you will have alcohol in your mouth, but your BAC levels haven’t gone up yet.
How Mouth Alcohol Can Result in False Readings from a Breath Testing Machine
DUI breath test devices aren’t supposed to measure the alcohol in your mouth. They are meant to measure the air from your alveoli, which are air sacs in the lungs. These alveoli are surrounded by capillaries, which are extremely thin blood vessels.
Capillaries are so thin that alcohol vapor can pass from the lungs to the blood and vice versa. As a result, any alcohol in the blood moves to the lungs, and when you breathe out, the alcohol is detected by the breath test machine. It then measures the amount and converts it into an approximate BAC reading.
The problem is that breath testing devices aren’t sophisticated enough to distinguish between air from the alveoli and air from the mouth itself.
Therefore, if there is alcohol in your mouth, it gets mixed into the sample and can artificially raise the BAC reading. Anything above 0.08% is illegal, and mouth alcohol can sometimes push the reading above this level.
Can You Test Positive on the DUI Breath Test if You Didn’t Drink?
Unfortunately, yes. Even if you haven’t had any alcoholic drinks, other items can leave traces of residual alcohol in your mouth, which can result in the DUI breath test giving you a positive reading.
Medicines, mouthwashes, and breath sprays are some of the common causes of residual mouth alcohol, even if you didn’t drink. Chewing tobacco can also create alcohol in the mouth.
In some cases, medical conditions like GERD, heartburn, and acid reflux can also create alcohol in the mouth. However, with these, it is more likely for mouth alcohol to be created after alcohol is consumed rather than entirely on its own.
These factors can falsely raise your BAC to levels that will put you in trouble.
What Is the Observation Period for a Breath Test?
In Nevada, if law enforcement suspects you of a DUI, they are required by law to observe for 15 continuous minutes before they take an evidentiary breath test – a chemical test, instead of the preliminary breathalyzer test.
This 15-minute observation period is made mandatory by the procedures that police officers must follow for DUI tests like breath and urine tests.
Why Is There a 15-Minute Observation Period?
A 15-minute observation period is required because mouth alcohol usually dissipates in about 15 minutes. As long as you do not introduce any other substance that contains alcohol in the mouth, any traces of mouth alcohol should be gone after this period.
Therefore, by observing the driver for 15 minutes, the officer can be sure that the driver does not introduce anything into the mouth or take any action that could contribute towards the creation of mouth alcohol.
This includes:
- Eating
- Drinking
- Smoking
- Using any breath sprays
- Burping (which can cause reflux)
- Regurgitation
- Vomiting
However, law officers often do not honor this observation period. While many will wait for 15 minutes before they take the test, they use this time to do something else – such as using their phone or filling out paperwork. As a result, a burp or regurgitation that could bring alcohol to the mouth can easily be missed.
How Does Mouth Alcohol Serve As a DUI Defense?
Your DUI defense attorney can use mouth alcohol as a defense against a DUI charge. This is applicable when:
- The officer who charged you did not wait for 15 minutes before taking the test. So, they have to wait a full 15 minutes and no less.
- The officer was not attentive or observing you continuously during the 15-minute period.
- There is evidence that the mouth alcohol was caused by another source, such as a digestive problem or GERD.
Is Mouth Alcohol a Valid Legal Defense?
Although the mouth alcohol defense is not always applicable, it is completely valid. In past cases and studies, there is evidence that a properly implemented breath test is not contaminated by mouth alcohol. Therefore, if it can be shown that the breath test was not carried out properly, the burden of proof falls on the prosecution.
The defense attorney – and sometimes witnesses – can find flaws in the procedure that the police took and get you an advantageous result.
For example, your charge could be reduced through a DUI plea bargain, or the jury could find you not guilty.
Charged With DUI? Let Us Help!
If you or someone you know is charged with a DUI, our attorneys can help! Feel free to contact us, and we can review your case and find the best defense for you.