Factors that Cause DUI False Positives | Worgul, Sarna & Ness, Criminal Defense Attorneys, LLC

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Factors that Cause DUI False Positives

Breathalyzer devices are powerful pieces of technology that help law enforcement keep our roads safe. However, many people don’t realize that they aren’t infallible. Just because the breathalyzer device says that your BAC is over the legal limit doesn’t mean that it actually is. There are a number of factors that can cause a DUI false positive.

Don’t let prosecutors convince you that the breathalyzer results are indisputable proof. If you’re facing DUI charges, you need an experienced DUI attorney who knows how to challenge breathalyzer results. At Worgul, Sarna & Ness Criminal Defense Attorneys, LLC, we believe that everyone is entitled to a fair process. Call us today at (412) 281-2146 or our online contact form to schedule a free consultation with one of our DUI defense attorneys.

Improper Calibration of the Device

Breathalyzer devices are complicated pieces of technology that require proper calibration in order to return accurate test results. Pennsylvania law requires that each device be calibrated within 30 days of use. Note that this isn’t a one-time obligation, but requires ongoing re-calibration. For example, a breathalyzer that was once calibrated but unused for more than 30 days must be re-calibrated. Once the device has been properly calibrated, the person who calibrated it must sign and date a certificate of accuracy. The certificate must be kept on file for three years from the date of the calibration test. Failing to properly calibrate the device (or prove that it has been properly calibrated with the proper documentation) can cause a DUI false positive and is grounds for dismissal of your DUI charges.

Residual Alcohol

When administering the breathalyzer test, the officer has to be especially careful that there is no residual alcohol in your mouth. In Pennsylvania, officers must wait 20 minutes before administering a breath test if they suspect that you have been driving while under the influence. During this time, they must observe that you do not drink any fluids, burp, vomit, eat anything, or smoke. Ingestion of any substance can cause a DUI false position, but especially burped or regurgitated alcohol or things like mouthwash.


There are a number of over-the-counter and prescription medications that can cause a DUI false positive:

  • Nyquil and other cold relief medicines that contain alcohol
  • Asthma medications
  • Oral gels containing anbesol

If you ingested any of these substances prior to taking a breathalyzer test, it could cause the results to be inaccurate. Other medications that could affect your metabolism or digestive system could also trigger a false positive. If you’ve been charged with DUI, you should carefully recount all of the various substances you had ingested that day so that your attorney can consider all of the possible options.

Medical Conditions

In addition to medications, your underlying medical condition could potentially cause a DUI false positive. The following medical conditions have shown to cause DUI false positives by rendering an inaccurately high BAC in breathalyzer tests:

  • Hyperglycemia
  • Diabetes
  • Acid reflux
  • Gastrointestinal reflux disease

People with diabetes, for example, have a high level of ketones in their system, which leads to acetone in their breath – a form of alcohol. People with acid reflux and similar conditions may regurgitate a little bit of alcohol from their stomachs, causing alcohol to be on their breath and rendering an inaccurately high reading on a breathalyzer device. Make sure you tell your attorney about any medical conditions you may have if you’ve been charged with DUI.

Rising Alcohol Levels

When evaluating whether there was a DUI false positive in your case, the timing of when you consumed your last drink, when you were pulled over, and when the test was administered may be critical. Your body doesn’t process alcohol the same way and at the same rate at all times. There are a number of factors that can affect how quickly your body absorbs the alcohol, which means that your BAC can change even after you’ve stopped drinking. As a result, it’s quite possible that your BAC could actually be higher when you were tested than when you were driving.

Contact a Pittsburgh DUI Defense Attorney if You Think Your DUI Is a False Positive

Many people believe in all honesty that they were able to drive safely and legally when they get pulled over for a DUI. Unfortunately, DUI false positives are more common than you think. Don’t let these charges jeopardize your future – speak with an experienced DUI attorney right away. The attorneys at Worgul, Sarna & Ness, Criminal Defense Attorneys, LLC work with people charged with DUI in Pittsburgh in order to make sure they get a fair result. If you’d like to schedule a free consultation, call us at (412) 281-2146 or complete our online contact form to learn about your options and how we can help you.