A breathalyzer test is sometimes used by police to confirm whether or not an individual was driving under the influence of alcohol. The results are often used as evidence at a DUI trial. However, many people question how reliable these tests really are.

A breathalyzer measures and detects molecules in breath alcohol, which is a vapor that escapes the body through breath after a person consumes alcohol. As with any test, there are factors that make it susceptible to error.

  • All breathalyzers have a margin of error. For example, a machine may measure breath alcohol at .08% but the actual percentage could be anywhere from .07% to .09%.
  • Instead of measuring blood alcohol concentration (BAC) directly, breathalyzers estimate BAC by breath alcohol levels, which can result in an incorrect result.
  • Radio frequency interference (RFI) from a police radio can also cause a breathalyzer to perform erroneously.
  • In order for a breathalyzer device to function properly, it must be calibrated regularly.
  • Mouth-alcohol contamination is also something to be considered. For instance, if a person burps or vomits shortly before testing, the breathalyzer might detect alcohol that is lingering in the mouth or stomach in addition to breath alcohol.
  • It is also possible for a test to be contaminated with the mouth-alcohol from a prior subject or atmospheric fumes.

The Law Office of Thomas Hogan is a DUI/DWI Law Specialist who is prepared to help in your time of need. Feel free to contact us if you are in need of help. Call (209) 214-6600 to speak with our Modesto California Attorneys.