Common Reasons for a False Positive on a DUI Breath Test

What Can Cause a False Positive Breathalyzer Test?

When an individual has been pulled over under the suspicion of drunk driving, he or she is often tested with a breathalyzer machine to determine blood alcohol content (BAC). If a police officer determines that a driver has reached or surpassed the legal limit of .08 percent, the driver is considered legally drunk and subject to a DWI arrest.

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However, many experts consider these breathalyzer tests to be inadequate at times.

False Positive Blood Alcohol Test

False readings for blood tests frequently occur based on various factors. The most common reasons for a positive blood alcohol test include improper calibration of the equipment, administering the test too soon, blood alcohol rising, health conditions and medications, or contamination of the sample.

The following are the most common reasons for a false positive on a breathalyzer test:

  1. Improper calibration of the equipment – There are specific guidelines that police officers must adhere to when calibrating and using a breath tester. When a breathalyzer is not adequately calibrated and maintained at the correct settings, the readings provided after testing may be false and inaccurate.
  2. Administer the test too soon – Alcohol residue in a person’s mouth may affect the readings, resulting in the device registers a BAC above the legal limit, despite the fact that the true reading is actually considerably lower. It is mandatory for police officers to wait no less than 15 minutes before testing a person when a DWI is suspected to protect the test from potential mouth alcohol resulting in a false positive. This means that if law enforcement observed an individual consuming alcohol, burping within the 15-minute period, or vomiting, the time limit needs to be restarted so that an accurate read is possible.
  3. Blood alcohol rising – For many individuals that have consumed alcohol, it may take between under one hour and three hours for the substance to be completely absorbed into the bloodstream. So if a breath test was administered in this timeframe, while the BAC rises, it can lead to a false depiction of what may be occurring within the person’s body. Levels may rise pass a specific point and then drop again.
  4. Health conditions and medications – There are a variety of medical conditions and types of medicines that may cause the reading to provide a false positive when administering a breathalyzer test. Common health conditions include acid reflux, gastrointestinal reflux disease, and continual or temporary heartburn. Due to the acid in the mouth, stomach, or esophagus, they may rise BAC levels and cause a false positive test reading.
  5. Sample contamination – Many environmental factors could affect the sample of a breath test. For instance, chemicals from cleaning supplies to sanitize the breathalyzer may result in a false positive. Or the liquor exhaled by previous individuals tested can have an impact.

If you have been arrested for a DWI and believe that you received a false positive DWI test result, our Minneapolis criminal defense attorney at Brockton D. Hunter P.A. is dedicated to protecting your rights and future. For more information, contact us and request a free consultation today by calling (612) 979-1112.