DUI Breath Tests Are Not the End of the Story

When you left the bar or your friend's house, you knew you had been drinking. Perhaps you thought enough time had passed since your last drink that you could safely drive home. In hindsight, it may have been better to err on the side of caution and call a cab. This truth hit home when police pulled you over.

If you submitted to a breath test and blew a .08, which is the legal blood alcohol concentration limit in Wisconsin and most states, you may have decided there was no point in fighting the evidence. However, before you accept a guilty plea, you should know some things about breath tests.

Reliability in question

A Breathalyzer or similar device does not actually test the concentration of alcohol in your blood. Unless police tested your blood, there is a good chance the results were inaccurate. In fact, even blood tests have their flaws, which a skilled defense attorney can recognize.

Instead of testing your blood, a breath test measures the amount of ethanol in your body. Ethanol is a component of alcohol. However, other chemicals in your body are so similar to ethanol that a breath analyzer cannot always distinguish between them. In addition, the calibration on breath devices assumes everyone and every situation is the same, but certain differences may skew test results, for example:

  • Changes in the air temperature
  • Abnormally high body temperature, such as if you are ill or have been exercising
  • Acetone in your body if you are dieting or suffer from diabetes
  • Exposure to certain chemicals, such as oil-based paints, gasoline or cleaning fluids
  • Blood or vomit in your mouth
  • Tobacco smoke
  • Electrical transmissions from police radios or cell phones
  • Certain foods you may have eaten

Breath tests do not always take into account whether the subject is a man or a woman even though there is a substantial difference in the cell volume of blood for each.

Protecting your rights

Police do not always recalibrate the machines often enough or properly maintain them for the most accurate readings. It is also well known that the smaller the device, the less likely the results will be accurate. Therefore, it may be in your best interests to refuse any roadside breath tests and wait until officers have taken you to the police station to test you.

As you can see, it is not always wise to allow the results of a breath test to determine whether you will accept a guilty plea for a DUI charge. A skilled attorney can challenge the evidence and defend you against the charges.