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Breath Test Defense

Were you given a breath test after your DWI arrest?

If you have been arrested for DWI, you were probably offered a breath test. The purpose of this test is to determine your blood alcohol concentration (BAC). In Texas, it is illegal to drive with a BAC of .08% or more. At Chernoff Law, one of our legal partners is board certified in criminal law, and our experience has shown us that there is a lot to be skeptical about regarding breath tests. A dedicated and knowledgeable Houston DWI attorney may be able to use the flaws in breath tests to your advantage.

Our state has one machine that is certified for use by law enforcement official in performing a breath test. This machine is called the Intoxilyzer 5000. It is supposed to conduct a self-check on a mixture of distilled water and alcohol. This mixture is called a “reference sample” and is usually prepared by a city crime lab employee. In theory, this machine should work well. In real life, this is not always the case and this is where we may be of service to you.

Facts Concerning Breath Tests

One large area of concern is the “reference sample” that is used. If the reference sample is incorrect, how can the test that is taken in the field be accurate? There are vast differences in the physiology of our bodies. Many people have physical conditions or have been in contaminated environments that may throw the accuracy of a test off. A recent court hearing found that there is no internal test to determine if the machine is operating at the correct voltage. The machine could, therefore, be operating at the incorrect voltage which would change the numerical interpretation of breath alcohol concentration.

An arrest and conviction for DWI can have serious and life-changing consequences. Large fines, loss of your driver’s license, jail time and other penalties can result from an unsuccessful DWI case. If convicted, it will go on your permanent criminal record and can affect future employment opportunities. Field sobriety tests are not perfect and final evidence of intoxication. In the case of a breath test, one can ask if the machine was properly calibrated or if it was even properly maintained. At times, the test is not administered correctly by the police officer. Anyone arrested for DWI does have legal rights. We feel it is important that those rights be protected.

If a client has taken a breath test it is absolutely vital that his or her attorney understand both the procedure used to obtain the specimen of breath and the way the machine measures that specimen. It has been our experience that, absent an effective defense presentation describing the frailties of the machine and the State’s breath-testing program, Juries have a tendency to believe the results of a breath test. Discussions with jurors after trials show that most walk into court with the impression that the State has done its necessary due diligence with regard to the machine used in State breath testing and has sufficiently trained its officers to give the test. They are shocked when presented with the truth.

However, truth will not set that accused citizen free unless DWI defense counsel is prepared and able to present that truth. In many cases, the defense will need to present an expert to introduce evidence of the machines failings. In every case the DWI lawyer must know how to carefully and effectively obtain contrary information from the expert presented by the State. The lawyer must be able to acquire and interpret repair and maintenance records. He must be conversant in technical language and be able to call out a State witness who makes questionable claims about the efficacy of the test machine. Quite simply, the lawyer must know what he is talking about, or the jury surely will penalize his client.

Breathalyzer Tests in Texas

The breath test machine currently utilized in Texas for DWI investigations is the Intoxilyzer 5000. It works through the process of infrared spectroscopy. In theory, the machine is supposed to evaluate its accuracy on a continuous basis. Between tests, the machine is programmed to analyze the concentration of alcohol in a known “reference sample” containing distilled water and alcohol. If it predicts this concentration within a certain range, it is assumed to be operating properly.

In addition, the machine is programmed to initiate a self-check program designed to identify any outside interference, such as radio waves and unusual chemical substances. Unfortunately, no independent entity has been able to check the Intoxilyzer’s software, since the company that produces the machine has thus far refused to reveal its source code. Questions about accuracy continue to arise as the company now markets a newer version of the Intoxilyzer, touted to be more precise than its predecessor.

The Flaws of Breath Testing

Many problems with the Intoxilyzer have been reported. Mouthwash and tooth implants may unfairly affect the composition of a breath sample. Unlike the “reference sample”, upon which the machine determines its accuracy, human breath can contain nearly a thousand different substances. In addition to varying breath composition, people vary in hematocrit level, which can cause breath alcohol concentration to vary wildly. Some people with diabetes, or who are on very low carbohydrate diets or who work around paint fumes may have substances in their breaths that will absorb the same wavelength as alcohol in an infrared spectrometer, skewing the machine’s results.

This firm has performed controlled testing on the Intoxilyzer 5000. In one case, a client registered a .18% breath alcohol concentration even though his blood alcohol level was only .05%. This result was achieved after the client had consumed only three 12 oz. beers! Naturally, this firm continues to remain skeptical of the Intoxilyzer’s specificity and fairness.