Criminal Lawyer

One of the most important changes in the way that DUIs are prosecuted has been the invention of the chemical breath test, commonly referred to as a breathalyzer. These tests involve machines that analyze a person’s breath for traces of alcohol and provide an allegedly objective measurement of a person’s blood alcohol content (BAC). However, people do not realize that these machines are actually quite fallible. There are a variety of different factors that can affect whether a person’s chemical breath test gives an accurate result.

The Mechanics of Chemical Breath Testing

Chemical breath testing works on the principle that the amount of alcohol in a person’s lungs is directly related to the amount of alcohol in their blood. Chemical breath testers use a variety of different methods of determining the alcohol content in a person’s lungs, which the machine can then use to calculate a BAC. The machines measure the alcohol in one of three ways.

One type of machine uses a color change to test for ethanol in a person’s blood. The machine has a special chemical in it that changes color when it reacts with alcohol. The machine can then measure how much the color has changed and use that to determine how much ethanol was in the sample.

The second type of machine that may be used to measure BAC uses infrared light to determine how much ethanol there is. Different chemicals absorb light differently, so machines can shine light through the sample and calculate the amount of alcohol present based on how the light was absorbed.

Finally, some chemical breath tests can use fuel cells to determine a BAC. Ethanol can react with certain chemicals to generate electricity, and the amount of electricity generated, which the machine can measure, depends on the amount of ethanol in the sample.

Breath Testing Errors

Despite these sophisticated testing methods, there are different ways that a chemical breath test can get a person’s blood alcohol content wrong. For instance, diabetics and people with certain other diseases often test high on a breath test. Diabetes increases the amount of acetone in a person’s blood and lungs. Acetone reacts much like ethanol, so the breath testing methods will read them as the same, even if the person has not been drinking.

Things like alcoholic mouthwash, burping, or hiccupping prior to the breath test can also skew the results. The test is designed to measure alcohol that gets into the lungs through the bloodstream. Mouthwash or burping can bring extra alcohol into a person’s mouth that makes the sample seem far more alcoholic than it actually was.

These are just some of the many ways that a breath test can generate an inaccurate result. There can also be issues with the malfunctions of the machine used to measure the BAC, as well as issues with the training and experience of the person who administers the test.

If you have been charged with DUI and want to learn more about the legal options available to you, contact an experienced Bloomington, IL criminal lawyer relies on to find out how we can help you defend against these charges.

Thank you to our friends and contributors at Pioletti & Pioletti for their insight into criminal defense and how a breath test works.