Breath Test Errors? In MY DUI Case? It’s More Likely Than You Think!

The breathalyzer: the do-it-yourself DUI identification tool. Popular for its ease of use, it is the police officer’s best friend when trying to collect evidence of suspected drunk driving. But nothing is perfect, and faulty breathalyzer readings have landed otherwise innocent people in jail on drunk driving charges.

When breathalyzers fail, thousands of potential DUI cases can be affected. Take, for example, recent events in Philadelphia, Pennsylvania, where between 500 and 1,000 DUI cases could be affected due to faulty readings in improperly calibrated breathalyzer units. Breathalyzers require yearly tune-ups to ensure the accuracy of their readings, and when those units are improperly calibrated, it is possible for people blowing into them to receive elevated readings indicating impairment, even if they aren’t actually impaired.

Are Breathalyzers Reliable?

Some studies have argued that breathalyzers are inherently inaccurate and should not be relied upon fully as an indicator of impairment. One such study from the Wisconsin State Laboratory of Hygiene found that only 33 percent of breath test results correlated with blood tests of the same subjects. That seems like an awfully wide margin of error that has real-life consequences for people who may not have actually broken any laws or who may be guilty of lesser charges than DUI.

In fact, there have actually been cases where courts have overturned DUI convictions on the grounds of the inherent limitations of breathalyzers. In the New Jersey case of State v. McGinley, four drivers convicted of DUI were exonerated because of the following reasons:

  1. Breathalyzers look for a 2100/1 blood-breath ratio, which says that 2100ml of a person’s breath contains the same amount of alcohol as 1ml of blood. This number is an average, and it is normal for people to have ratios closer to 1100/1 or even 3200/1, so the machine could skew results.
  2. The temperature of the breathalyzer can affect results.
  3. Human body temperature can affect results.
  4. The composition of a person’s blood, particularly hematocrit levels, can affect results.

As a person pulled over for DUI, you have no way of knowing if the breathalyzer you blow into has been manufactured or maintained correctly. This could lead to charges for you resulting in expensive fines, potential jail time and the loss of your driver’s license. It is always a good idea to have a DUI defense attorney look at your case to see if you are being charged with offenses you did not commit based on faulty evidence.

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