How Mouth Alcohol Can Affect Breathalyzer Results During a DWI Investigation

Mouth alcohol can affect breathalyzer results by temporarily increasing the amount of alcohol detected in a person’s breath, potentially producing a reading that does not accurately reflect their blood alcohol concentration (BAC). This can happen after consuming alcohol, using certain mouthwashes, or experiencing acid reflux or vomiting shortly before testing.

When a breathalyzer result raises questions about possible mouth alcohol contamination, a DWI lawyer can help review the testing procedure, identify potential sources of error, and determine whether the result accurately reflects the driver’s level of impairment. Examining how the test was conducted can be important when challenging the evidence presented during a DWI investigation.

Understanding how mouth alcohol affects breath testing can help explain why officers follow specific testing procedures and why the timing of a breath sample may matter. The following sections explore the causes of mouth alcohol, its impact on test results, and the legal considerations involved in a DWI case.

Overview of Mouth Alcohol

Mouth alcohol refers to alcohol that remains in the mouth, throat, or upper digestive tract rather than alcohol that has entered the bloodstream and reached the lungs. A breathalyzer is designed to estimate BAC by measuring alcohol in a person’s breath, particularly alcohol that exchanges between blood and air in the lungs.

However, when alcohol remains in the mouth, it can enter the breath sample directly. This may produce a higher reading than the person’s actual breath alcohol level would otherwise indicate. Mouth alcohol is generally temporary, but its presence can affect the reliability of a test if the sample is collected too soon after exposure.

Common Causes of Mouth Alcohol

Several situations can leave alcohol in the mouth or introduce substances that may interfere with breath testing.

• Recent alcohol consumption: Drinking shortly before a breath test can leave residual alcohol in the mouth.
• Alcohol-based mouthwash: Some mouthwashes contain alcohol that may temporarily affect a breath sample.
• Acid reflux: Stomach contents containing alcohol may reach the mouth through reflux or regurgitation.
• Vomiting or belching: These actions may bring alcohol-containing stomach contents into the mouth, potentially affecting the reading.

The effect depends on the circumstances, including the timing of the exposure and the testing procedure used.

How Mouth Alcohol Affects Breathalyzer Results

Mouth alcohol can cause a falsely elevated breathalyzer reading because the device may detect residual alcohol that does not represent alcohol exchanged from the blood through the lungs. As a result, the reported BAC may not accurately reflect the person’s blood alcohol concentration at the time of testing.

This does not mean every elevated breathalyzer result is inaccurate. Properly administered tests are designed to reduce the influence of mouth alcohol, and the significance of a suspected problem depends on the available evidence.

Many evidential breath-testing procedures include an observation period before the sample is collected. During this period, an officer watches for activities such as eating, drinking, smoking, vomiting, or belching that could compromise the sample. The specific requirements depend on the jurisdiction and testing equipment.

Legal Considerations in a DWI Investigation

Breathalyzer results may serve as evidence in a DWI investigation, but they are not necessarily the only evidence used to evaluate a case. Officers may also consider driving behavior, physical observations, field sobriety tests, and other available evidence.

In Texas, Texas Penal Code § 49.01 defines intoxication for purposes of the state’s intoxication-related offenses. The definition includes having a blood or breath alcohol concentration of 0.08 or more, as well as not having the normal use of mental or physical faculties because of alcohol, a controlled substance, a drug, or another specified substance.

If mouth alcohol may have affected a breath test, relevant questions can include whether the required observation period was followed, whether the equipment was properly maintained, and whether the testing records show any irregularities. The legal significance of these issues depends on the facts and applicable law.

How Breathalyzer Evidence May Be Challenged

When a breathalyzer result is disputed, the circumstances surrounding the test may deserve careful review. Relevant records can help establish whether the procedure was followed and whether any known source of mouth alcohol was present.

A review may examine:

• The timing of alcohol consumption or exposure to alcohol-containing products.
• Whether the required observation period was completed.
• The breath-testing device’s maintenance, calibration, and inspection records.
• The officer’s notes and documentation of the testing process.
• Whether other evidence supports or conflicts with the reported result.

A suspected testing error does not automatically invalidate a DWI charge. However, identifying a specific procedural issue or a credible source of contamination may help assess the reliability and admissibility of the breathalyzer evidence.

Key Takeaways

• Mouth alcohol can temporarily raise breathalyzer readings without accurately reflecting blood alcohol concentration.
• Recent drinking, alcohol-based mouthwash, acid reflux, and vomiting may contribute to mouth alcohol contamination.
• Observation periods help reduce the risk of mouth alcohol affecting evidential breath tests.
• Texas Penal Code § 49.01 defines intoxication for purposes of Texas intoxication-related offenses.
• Testing procedures, equipment records, and other evidence may help determine whether a breathalyzer result is reliable.