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Are Breathalyzers and Blood Alcohol Content Tests Always Accurate?

 Posted on February 08,2021 in Driving Under the Influence

Fairfield CT DUI defense attorneyIn Connecticut, when a law enforcement officer pulls a driver over with reasonable suspicion of driving under the influence of alcohol (DUI), they will often ask the driver to take a chemical alcohol test such as a breathalyzer. If the driver’s blood alcohol content (BAC) is 0.08 or more (or 0.02 percent or more for an underage driver) he or she will be arrested and charged with DUI. If you or a loved one was recently arrested under these circumstances, you may wonder if it is possible that the breathalyzer results were inaccurate.

How Does a Breath Alcohol Test Work?

If you have ever been in a crowded bar, you have probably noticed that the smell of alcohol can linger on a person’s breath. Breath alcohol tests like breathalyzers test the amount of alcohol in a person’s breath and use this to determine the person’s blood alcohol content. The two types of breath alcohol testing devices used by police are preliminary alcohol screening devices and evidential breath test devices. A preliminary alcohol screening device or portable breath test is typically used during a traffic stop. These handheld devices are smaller and more convenient for roadside BAC testing than evidential breath test devices; however, they can also be less accurate than evidential breath test devices.

Breath Alcohol Testing Errors

Breathalyzers are carefully designed and calibrated to be as accurate as possible. However, it is possible for a preliminary alcohol screening device or evidential breath test device to display an inaccurate BAC. Errors may be caused by:

  • The driver’s unique physiology – A person’s body weight, medical conditions, body temperature, and other bodily differences can influence the results of a breath alcohol test.

  • Improper calibration – Breathalyzers are typically calibrated by testing a solution with a known alcohol content. Improper calibration or infrequent calibration can lead to inaccurate results.

  • Mouth-alcohol contamination – Breath tests measure the alcohol in a person’s lungs. If the person has alcohol in their mouth, this will yield an artificially high result.

Evidence of any of these errors can be used in building a defense strategy to help the driver avoid conviction.

Contact a Stamford DUI Defense Attorney

A conviction for driving under the influence can lead to significant criminal penalties. If you have been arrested and charged with drunk driving, contact Fairfield County criminal defense lawyer Daniel P. Weiner for help defending against these charges. Call our office at 203-348-5846 to schedule a free, confidential consultation to discuss your case.



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