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Defending a DUI Breath Test Case: Mouth Alcohol and the 15 Minute Observation Period


If your client has been charged with a DUI related offense, his blood alcohol content (BAC), will have a dramatic impact on what sanctions he will likely face. For example, a defendant charged with a second offense will be subject to a mandatory minimum sentence of ten days in jail with either no BAC reading or one which is below .15%. However, for the same second offense, a defendant faces a mandatory minimum sentence of six months in jail if his BAC is .15% or higher. The disparity in sentences based on BAC level is even more pronounced for a defendant facing a third offense. With either no BAC or one which is below .15%, a suspect faces a mandatory minimum sentence of one year in jail and with a .15% or higher reading, a three year mandatory minimum sentence. These severe penalty enhancements, as well as cases with borderline, .08%-.10% readings, require a successful DUI defense practitioner to be fully apprised of how breathalyzers operate and what challenges can be made to the BAC reading in your case. This article will touch upon the topic of “mouth alcohol” as it relates to the testing officer’s statutory obligation to conduct a fifteen minute observation of the suspect prior to administering a breath alcohol test.

Intoxilyzer Model 5000

Rhode Island police departments utilize the Intoxilyzer Model 5000 as its primary evidentiary instrument in breath alcohol analysis. Manufactured by CMI Inc. of Owensboro, KY, the Intoxilyzer 5000 uses infrared spectrometry to measure breath alcohol content. A DUI suspect will blow into a tube which leads to a breath chamber cylinder. The machine shines an infrared light through this cylinder as filter wheels are spinning on the other end. As the infrared light shines, the alcohol molecules will absorb the light at a particular frequency. The Intoxilyzer will measure the difference between the light initially emitted and the light received after absorption from the alcohol molecules. The machine will then use a predetermined software program to convert this measurement into a numerical value.

Mouth Alcohol

When a breath sample is provided by a suspect, the Intoxilyzer 5000 operates on the assumption the breath sample provided was air exhaled from deep within the lungs (alveolar air). The ethanol molecules in this breath sample are then measured by the machine and multiplied by what is known as a partition ratio. The partition ratio used in this machine is 2100:1, which means the alcohol found in 2100 parts of deep lung air will contain the same amount of alcohol found in one part of blood. But what if the alcohol in the breath sample is not from the lungs? “Mouth Alcohol” is a term used to describe any residual alcohol in the mouth or esophagus. Alcohol can be present in the mouth for a number of reasons. The most common reason is when the individual has recently consumed alcohol as it takes approximately 15-20 minutes for the alcohol to dissipate through the rinsing action of saliva. In defending a DUI breath test case, most lawyers will confront fact patterns where the defendant was in police custody well past a twenty minute time period, so recent alcohol consumption most likely will not be a basis for raising a “mouth alcohol” challenge. However, vomiting, hiccupping, crying and belching are all additional causes of mouth alcohol and will most likely provide the basis for mounting a challenge to the BAC reading. So how likely is it a burp or a hiccup would compromise the Intoxilyzer’s blood alcohol analysis? Enough so that the Rhode Island Department of Health (DOH), the agency charged with regulating the administration of breath alcohol testing, mandates action to prevent such interference.

DOH Breath Test Regulations

Rhode Island General Laws Section 31-27-2(2)(c) sets forth conditions which must be met if blood alcohol content evidence, as shown by a chemical analysis of the defendant’s breath, is to be admissible. One such mandated requirement is as follows: “The test was performed according to methods and with equipment approved by the director of the DOH of the state of Rhode Island and by an authorized individual.” Therefore, this section vests the DOH with the authority to specify the procedures and methods for which breath test analysis must be performed in Rhode Island. The DOH regulations pertaining to breath test analysis clearly lay out the protocol that must be followed when administering a breath test to a suspect for evidentiary purposes. The relevant section that deals with the dangers of mouth alcohol in compromising the validity of the breath testing analysis is found in the “Rules and Regulations Pertaining to Preliminary Breath Testing and Standards for the Determination of the Amount of Alcohol and/or Drugs in a Person’s Blood by Chemical Analysis of the Breath, Blood and/or Urine or other Bodily Substances, Section 8.2(b).” This section provides, “The breath samples shall be taken after the suspect has been observed for a minimum of fifteen (15) minutes to ensure that the suspect has not ingested or inserted any substance into his/her mouth, or caused any residual mouth alcohol to occur.


What does this mean for a lawyer defending a DUI breath test case? How do you successfully challenge a BAC reading where the testing officer failed to properly observe the suspect for the required fifteen minute period? The DOH regulates how the breath testing analysis must be performed but not following these regulations does not lead to a “per se” invalidation of the results. The defendant has the burden of proving that non-compliance with the DOH regulations actually compromised the validity of the test results. In essence the government regulates how an instrument must be used, the government fails to use the instrument in that proscribed way and the defendant is left with the daunting task of proving to the court that a sub-standard testing procedure may have actually led to a sub-standard test result. There is good reason why the DOT requires a fifteen minute observation period, it’s just left up to defense counsel to develop that reasoning in open court.

– James P. Marin, Esq.

“James P. Marin practices DUI defense
in Rhode Island and is certified as
a Breath Alcohol Testing Technician.”