Behind the Breathalyzer

If you or someone you know and care about is accused of committing a DWI, then the chief piece of evidence the prosecution will likely use will be your Breathalyzer test. What exactly is a Breathalyzer, and how does it work? These and other questions are at the center of many motions, orders, and trials involving DWIs.

One of the primary questions that comes up again and again is, “How do breathalyzers work?” After all, the law clearly punishes a person with an unacceptable blood-alcohol content, not breath-alcohol content. So, how can a test of the breath accurately measure the amount of alcohol in a person’s blood stream?

Under the prevailing theories of how breath-alcohol levels relate to blood-alcohol levels, the amount of alcohol measured in the breath can be extrapolated to conclude how much there is in the blood. For example, when alcohol is consumed the alcohol is immediately distributed throughout the body, the intestines, stomach, and bloodlines. The level of alcohol throughout your body impacts a number of things like reaction time, decision making, and other important aspects of human behavior.

As the theory goes, once the level of alcohol in the breath is detected, it can then be deduced what it would also be in the blood. There are different ways for the police to detect breath alcohol levels, and different machines that are used by different police departments. The different types of breathalyzers are:

  • One that creates a chemical reaction once alcohol in the breath meets the chemical on a paper that changes colors;
  • Infrared spectroscopy machines that detects the level of alcohol through infrared technology;
  • Chemical reactions in a fuel cell in a machine connected to a breathalyzer.

All of these technologies are typically accepted by courts to provide evidence of a person’s blood-alcohol content in connection with a DWI.

Why the Science Matters

The kind of technology used by police departments matters in more way than one. To actually convict someone of DWI in Texas the state must show beyond a reasonable doubt that a driver was driving impaired by using alcohol, or that the driver had a blood-alcohol content over .08. To prove their case, prosecutors typically introduce evidence of breathalyzer tests, and testimony by an expert about how the technology works, and why it applies given the evidence in a particular case.

A major job of any defense team to a DWI charge is discrediting and showing why these tests should not be used. While there is scientific evidence and theories about how and why in theory a breathalyzer should show a blood-alcohol content, that does not make it a fact. In fact, the science behind the use of breathalyzers and their reliability are constantly being challenged by scientists and important questions need to be raised in any prosecution where the chief bit of evidence used is a breathalyzer result.

At the Wilder DWI Defense Firm you can rest assured that our defense of your DWI charges will include every reasonable argument on the reliability of breathalyzer machines. If you are facing DWI charges, contact us today for a free consultation about your case.