Breathalyzer Test Results: New Study Confirms Their Unreliability
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Breathalyzer Test Results: New Study Confirms Their Unreliability

Posted On - November 14th, 2019 | By Tim Clancy | Category - Uncategorized

BACtrack Mobile in At&T Park

Breathalyzer tests have been used for years by law enforcement when they have stopped someone for suspicion of driving while intoxicated (DWI). The tests are generally done by the roadside and require a driver to blow into a tube attached to the breathalyzer machine, which then registers a blood alcohol content (BAC). The BAC results are later used to either entice a defendant to plead guilty, or a BAC of 0.08 or higher is introduced as evidence at a trial. In Texas, if a driver refuses to submit to the test, they will have their driver’s license suspended.

For years, Texas criminal defense attorneys have been challenging the results of the test as being unreliable. In fact, there are many situations in which the breathalyzer machine will record a false positive. The machine may not have been calibrated according to regulations, the test may not have been properly administered, the driver may have a medical disorder, have just used hand sanitizer, or any number of other situations that can result in a false positive.

An investigative report recently published in the New York Times verifies the concerns of drivers and their attorneys as to the reliability of these tests. The Times interviewed more than 100 lawyers across the country as well as scientists, executives and police officers. The investigative reporters reviewed “tens of thousands of pages of court records” along with confidential emails and contracts between manufacturers of the breathalyzer machines and law enforcement agencies. The results were somewhat astounding.

State Courts Tossing DWI/DUI Convictions Based on Breathalyzer Test Results

In the last year alone, judges have refused to consider the results of more than 36,000 breath tests, finding the machines were not properly calibrated or human error in administering the tests invalidated the results. When improperly calibrated, results may be increased by up to 40 percent.

Human error in administering the tests also creates false positives. It was discovered that police officers used a machine that actually had rats nesting inside of it, which threw off the results of the tests. Fortunately, the courts invalidated the results!

Other problems with the machines discovered by this investigation include:

  • Serious problems with the software programming was discovered. Even so, many state courts refuse defense attorney requests to analyze the software.
  • Breath samples were not kept below 93.2 degrees which then registered inaccurately high results.
  • In Colorado, it was discovered that records showed a technician had calibrated dozens of breathalyzers that he testified he had never touched.
  • A science director swore in an affidavit that her digital signature had been certifying machines she had never tested as accurate. Her signature was used for this purpose even after she had left for another job.


As one attorney was quoted as saying, “If we are going to put people in jail and punish people, take their liberties away, take their licenses away, we have an obligation to be accurate.”