Common Breathalyzer Test Errors


When a breath alcohol test device makes a reading, many assume that the reading is accurate – hard evidence written in stone that the driver in question was drunk at the time of his or her arrest. However, this is simply not the case. While police officers and news reporters announce alcohol breath test results as fact, the truth is that small difference in temperature, breathing, calibration, and other factors can change Breathalyzer blood alcohol content results by up to one third.

Specifically, in Missouri, the Missouri Department of Health has faced years of controversy concerning the approval process surrounding the Intoxilyzer 5000 and the BAC Datamaster – breath test devices that have been widely criticized and that other governments around the world have found inaccurate.

Here are just a few ways in which a breath alcohol test can go wrong:

  • Changes in breathing patterns. Heavy breathing can decrease your blood alcohol content (BAC) by up to 20 percent. Holding your breath can increase your BAC by 28 percent. This means a strange breathing pattern could lead to a wrongful DWI arrest. 
  • Changes in temperature. Both the temperature of the air and the temperature of the subject can change the BAC reading, and Breathalyzer machines must be calibrated often and correctly to prevent faulty readings.
  • Improper use. Human error is a large factor in false BAC readings, as many law enforcement officers may not correctly use the device each time they take readings. Also, the machines may become less accurate over time or through repeated use.In other cases, officers may not have been properly trained to use the device. 
  • The detection of other chemicals and substances. Although breath alcohol tests have improved over time, many still mistake other substances for alcohol. Studies by the National Highway Traffic Safety Administration (NHTSA) have shown those with diabetes and those on diets can register falsely high blood alcohol levels. Another study has shown that asthma suffers are likely to blow false positives on breath alcohol machines. 
  • Shoddy machine repairs. In some cases, breath analysis machines are repaired by those without the knowledge or skills to do so, rendering the device inaccurate. Proper maintenance is key to achieving accurate numbers, but many breath test machines are not regularly or correctly maintained. 
  • Mouth-alcohol contamination. If the breath alcohol machine reads alcohol from the mouth, stomach, or throat instead of from the lungs, the readings can skyrocket. Although Missouri authorities are taught to wait 15 minutes before administering the blood alcohol test, mouth alcohol can still interfere with readings, as can a small belch or burp.

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