Do breath test devices produce reliable results?

On Behalf of | Jan 18, 2022 | Criminal Defense |

If an officer pulls you over on suspicion of drunk driving, they may ask you to submit to a breath test. Roadside breath test devices are designed to determine a driver’s blood alcohol content level without taking an actual blood sample. Studies reveal, however, that breath test device results may not be accurate.

According to research from the State University of New York at Potsdam, at least one in four people who take a breath test will have elevated results. In some cases, this may lead to a wrongful DUI arrest and possible conviction.

How do breath test devices work?

Breath test machines detect ethanol alcohol in an exhaled breath sample. It then converts that into a blood alcohol content level. Blood tests, on the other hand, measure BAC levels directly. When comparing the BAC reading from a breath test to blood test results, researchers found a 15% discrepancy in some cases.

What factors affect breath tests?

In addition to measuring the amount of ethanol alcohol in a breath sample, breath test machines detect other methyl group structures, some of which are found in saliva. Other factors that can affect breath test readings include the following:

  • Relative humidity and temperature of the air
  • Inhaling fumes from gasoline, cleaners and paint
  • Static interference from cellphones and officer radios
  • Food, drink, blood or vomit in the mouth
  • Regular calibration of machines

Officers must use breath test machines properly to get accurate results as well. Because there are a number of factors that can alter breath test results, the results should not be admitted as evidence in a DUI case.

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