Are DUI Alcohol Breath Tests Accurate? 

 Posted on October 14, 2022 in DUI

Anyone who has been stopped on suspicion of drunk driving is familiar with alcohol breath tests or "breathalyzers." These devices are used by the police to determine if a suspect has been drinking. The officer instructs the driver to blow into the device. After a few moments, the device displays a number indicating the driver's blood alcohol concentration (BAC). Are these devices accurate? Can extraneous factors interfere with the device's ability to detect intoxication? Can an individual charged with driving under the influence (DUI) avoid conviction if the breath alcohol device results were incorrect?

Factors That Can Interfere with Breath Alcohol Tests

Breath alcohol tests determine a person's BAC by analyzing the amount of alcohol on their breath. However, these tests are not infallible. Various circumstances can interfere with the test and lead to inaccurate or unreliable results.

Breathalyzers must be regularly calibrated to ensure accuracy. If a device is not properly calibrated, it may give a false reading. The test could also be inaccurate if an unqualified person administered the test or if the device was malfunctioning.

Mouthwash or breath mints can also contain alcohol. This means that if a driver uses one of these products before taking a breath test, the test may show a higher BAC than the driver's true BAC. Even dieting can lead to inaccurate results. Some diets involve fasting or the elimination of carbohydrates which cause substances called acetones to be produced in the body. Outdated breath testing devices may not be able to tell the difference between acetones and alcohol.

The timing of a breath alcohol test can also influence the reliability of the results. The "rising blood alcohol defense" is based on the fact that a person's BAC will continue to rise for some time after they stop drinking. If a driver is given a breath test long after the traffic stop, the results may show a BAC that is higher than it actually was when they were driving.

Extraneous factors like these demonstrate that there is always some margin of error when it comes to breath alcohol tests. If you have been charged with DUI based on the results of a breathalyzer test, you may be able to challenge the accuracy of the test results in court.

An Experienced Naperville DUI Defense Attorney Can Help

The DuPage County drunk driving defense lawyers at J. Aldrich Law, P.C. can protect your rights after a DUI arrest. Call us at 630-953-3000 for a free consultation with a knowledgeable member of our team.

Sources:

https://www.ilga.gov/legislation/ilcs/fulltext.asp?DocName=062500050K11-501

https://www.menshealth.com/health/a26063314/ketosis-breathalyzer-alcohol-false-positive-low-carb/