How Mouth Alcohol can Act as a California DUI Defense

Mouth alcohol is exactly what you'd expect it to be...residual alcohol that lingers in the mouth. The reason that mouth alcohol plays a significant role in fighting a California DUI is because, when present, it masks the more accurate deep lung air that breath testing instruments are designed to measure.

As a result, mouth alcohol produces a falsely high BAC result...and can cause innocent people to get arrested for DUI.

How mouth alcohol is created

Mouth alcohol is created in a number of ways.

• GERD, acid reflux, and/or heartburn can produce mouth alcohol and adversely affect your DUI breath test.



• Medicines containing alcohol, such as Nyquil, can create mouth alcohol, which can lead to a false DUI arrest.



• Mouthwashes or breath sprays containing alcohol, such as Listerine, can produce mouth alcohol and therefore trick DUI breath testing machines.

And

• Dental work that traps food and liquid in the teeth can result in a mouth alcohol situation, resulting in a false high BAC.

If, prior to submitting to your California DUI breath test, you were possibly affected by any of these factors, your California DUI defense attorney will likely challenge your breath test results. This is because of the fact that alcohol found in the mouth is not representative of the amount of alcohol that is actually in your blood.

How California DUI breath testing instruments measure your blood alcohol concentration (BAC)

Breath testing instruments are designed to measure alcohol found in the deep lung tissue (also called alveolar air).¹ Aside from a DUI blood test², deep lung air contains the most accurate representation of the amount of alcohol found in your body. But when mouth alcohol exists, it produces a breath sample with a hyper-concentration of alcohol, and therefore also an inaccurate BAC level...as well as possible bogus California Vehicle Code 23152b DUI charges against the suspect.³

DUI breath testing instruments multiply the alcohol present in a breath sample by 2,100 to calculate a person's blood alcohol concentration (BAC). As a result, any amount of residual alcohol found in the mouth can result in a significant discrepancy in one's true BAC.

This seemingly arbitrary number of 2,100 is the average blood-to-breath ratio. A "blood-to-breath ratio" correlates the amount of the alcohol in the air of a person's lungs to the amount of alcohol in his/her blood.⁴

Specifically, the ratio is 2,100:1, which means the amount of alcohol in 2,100 milliliters of breath is considered equivalent to the amount in 1 milliliter of blood.⁵ The problem is that this ratio isn't constant, nor is it applicable to all individuals.

In fact, the California Supreme Court addressed this fact in a July 2009 case entitled People v. McNeal. The Court stated that this blood-to-breath ratio (also known as "partition ratio") varies greatly both in the general population and within an individual. As a result, the court held that evidence about partition ratio is admissible in court, because someone with an extremely low ratio of 1,100, for example, would have an overstated BAC by as much as 50%.⁶

Why the prosecution's argument that mouth alcohol quickly dissipates can be misleading

Although it is true that mouth alcohol dissipates fairly quickly, this is most often the case with (1) someone who drinks alcohol right before a breath test, or (2) someone who "burps" up a small amount of mouth alcohol. This is because the alcohol that is introduced into the mouth in either of these scenarios is limited and absorbs quickly into the membranes.

However, as widely-respected Van Nuys DUI attorney Darrell York explains⁷, "An individual suffering from chronic GERD, acid reflux, or heartburn, may continuously produce mouth alcohol. When this is the case, mouth alcohol will not dissipate as long as alcohol is present in the stomach. As a result, this individual will almost always produce a false high BAC based on the introduction of mouth alcohol into the breath sample."

If you have additional questions or would like to discuss your case confidentially with one of our California DUI defense attorneys, please don't hesitate to contact us. We have local DUI law offices in the San Francisco Bay area, San Jose, Ventura, Los Angeles, Orange County, San Bernardino, Riverside, and several surrounding areas.

You may also find helpful information in our related articles on How GERD affects DUI Breath Testing, California DUI Breath Testing, Vehicle Code 23152b Driving with a BAC of 0.08%, and Fighting a California DUI.

Legal References:

¹People v. McNeal (2009), 46 Cal.4th 1183, 1191. ("When a subject blows into a breath-testing machine, the device measures the amount of alcohol vapor expelled into alveolar spaces deep in the lungs.")

²Forensic experts believe that DUI blood tests are the most accurate tests available to determine the actual amount of alcohol in a person's system.

³American Medical Association's Committee on Medical Problems -- Manual for Chemical Tests for Intoxication (1959). ("True reactions with alcohol in expired breath from sources other than the alveolar air (eructation, regurgitation, vomiting) will, of course, vitiate the breath alcohol results...") Contact us to learn more about the specifics of how we present a mouth alcohol defense.

⁴See People v. McNeal, endnote 1 above at 1188. ("Whereas a blood test directly measures the subject's blood-alcohol level, a breath sample must be converted to derive a blood-alcohol percentage. The conversion factor, known as a "partition ratio," reflects the relationship between alcohol measured in a person's breath and alcohol in the blood.")

⁵See same. ("Breath-testing machines in California incorporate a partition ratio of 2,100 to 1, which means the amount of alcohol in 2,100 milliliters of breath is considered equivalent to the amount of alcohol in 1 milliliter of blood.")

⁶See same at 1198. ("For someone with an extremely low ratio of 1,100 to 1, for example, use of the 2,100-to-1 partition ratio would overstate blood-alcohol content by almost 50 percent.")

⁷Van Nuys DUI attorney Darrell York is a former Glendale Police Officer who now uses his invaluable experience to defend clients accused of DUI in Ventura, Van Nuys, Burbank, Glendale, and Pasadena.

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