Are breath test devices reliable?

Washington law enforcement officers use breath test devices during DUI stops. Studies show that these devices may be unreliable.

When people choose to drink and drive in Washington, they run the risk of getting pulled over and charged with a DUI. Law enforcement officers use hand-held breath test devices to determine whether a motorist is intoxicated. Yet, multiple studies show that the results from breath test devices are inherently unreliable and may be inaccurate in some cases. These false readings may result in a wrongful DUI charge and conviction of an innocent person. According to the State University of New York at Potsdam, one in every four people tested using a breath test device had inflated results indicating that their blood alcohol content level was higher than it actually was.

How do breath test devices work?

People who are suspected of drinking and driving may be asked to submit a breath sample into a hand-held breath test device. The breath analyzer then detects the presence of alcohol in the breath sample, and converts the breath alcohol content level into a blood alcohol content level. This conversion process does not always yield accurate results.

A study conducted by the State University of New York at Potsdam found that breath test devices detect more than just the ethyl alcohol in a breath sample. It also picks up methyl alcohol groups that have a similar structure to ethyl alcohol, but are not found in alcohol. In fact, methyl alcohol groups can be found in compounds contained in human saliva.

Factors that affect a breath test reading

In addition to detecting more than the amount of alcohol found on a person's breath, a breath test can be affected by the following:

  • The presence of tobacco smoke, dirt or moisture in the air
  • Interference from police radios and cellular devices
  • Trace amounts of vomit or blood in the driver's mouth
  • Whether the driver has had anything to eat within 15 minutes of the test
  • Whether the driver has been exposed to paint, cleaner or paint thinner fumes

Breath test accuracy is also dependent on whether or not the machine has been properly calibrated. Law enforcement officers must be able to use the hand-held breath test device properly, as misuse is another common factor that leads to inaccurate BAC results and false DUI convictions.

Obtaining legal representation

People who have been charged with a DUI in Washington may want to receive legal assistance from a criminal defense attorney who has a good understanding of state and national laws. If you were pulled over on suspicion of drunk driving in Washington, an attorney may be able to ensure that all of your rights are upheld in a court of law.

Keywords: DUI, breath test, arrest, penalties