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How reliable are Breathalyzer test results?

People who find themselves facing driving under the influence (DUI) charges in Tennessee may have many questions about the pending charges. One common concern is the accuracy of chemical breath tests. These tests, commonly referred to by the brand name Breathalyzer, are often the cornerstone of a DUI charge.

Law enforcement in Tennessee will often use a breath test to determine if motorists driving erratically have alcohol in their bodies. As these tests are relatively non-invasive, law enforcement with probable cause, such as a failed field sobriety test, can ask drivers to complete breath tests. Refusing to take the test violates the state's implied consent law, which can result in arrest and suspension of your license.

How do breath tests work?

In order to administer a breath test, law enforcement must get you to blow into the device. When you do so, the machine analyzes the air you exhale. It used infrared light to locate ethanol molecules. Many compounds could trigger a positive result in an ethanol test, including acetone and alcohol.

When you drink alcoholic beverages, the alcohol in your stomach gets absorbed into your bloodstream. From there, trace amounts of the alcohol in your blood end up vaporized and excreted through your lungs. Exhaling releases this alcohol, which can cause a positive result on a breath test. The level of alcohol in your breath can help law enforcement then estimate your blood alcohol concentration (BAC), even though the test does not directly measure your BAC.

When do breath tests show inaccurate results?

There are a number of situations that can skew the results of a breath test. The first is inadequate calibration of the device. In order to ensure accurate results, each testing unit should be routinely inspected and calibrated. Another potential issue comes in the form of user error if the officer administering the test makes a mistake.

Even if the testing unit functions perfectly, there are many scenarios that can result in false positive breath tests. Uncontrolled diabetes is one such issue. People experiencing diabetic ketoacidosis could have acetone on their breath. This compound could result in a false positive result.

Certain medications could also cause unreliable results in a breath test, as could several other medical conditions.

Speak up if you suspect an issue with your test results

If you have reason to believe that your breath test results are inaccurate for any reason, you need to assert your rights. Understanding how these devices work can help you better understand the risk factors for an inaccurate result. Challenging the accuracy of these test results could help you develop a successful defense against pending DUI charges.

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Jack P. Sherman, Attorney at Law
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Memphis, TN 38103

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Phone: 901-233-3474
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