Breath Test in Texas

Currently Texas has one breath test machine certified for law enforcement use, the Intoxilyzer 5000. Very simply put, it works by computing the absorption of light at a certain wavelength when a sample of breath is blown into a chamber. The process is called infrared spectroscopy, and it is well accepted scientifically.

The machine is assumed to be operating properly if its self-check program doesn't identify any interference, and if it predicts with relative accuracy the alcohol concentration of a distilled water and alcohol mixture called a "reference sample". Usually, a city crime lab employee prepares this mixture. If the test of the "reference sample" doesn't' match up with the predicted value, the machine is supposed to invalidate the test.

It all sounds great. This benevolent, blind instrument hums along, fairly evaluating whether each test subject had too much to drink, continuously checking itself for accuracy. The problem is it doesn't always work out that way. Both anecdotally and scientifically, there's reason to believe that innocent people arrested after a field test have been convicted on the basis of incorrect test results.

There is a lack of information about how the Intoxilyzer computes its information. The software is legally protected and the company, CMI, Inc., has so far refused to reveal the source code. The current machine used, the Intoxilyzer 5000, is not even the latest in a series of breathalyzers built and marketed by CMI, Inc. It now sells the Intoxilyzer 8000. Since CMI continues to keep its computer program secret, it begs the question; what made the 5000 more accurate than its predecessors? And, what flaw in the 5000 required the creation of the 8000?

The "reference sample" is a concern. There is obviously a great deal of difference between human breath, which can very due to many substances, and the relatively pure mixture of the two substances found in the "reference sample". Also, what independent check is there that the "reference sample" was mixed correctly? If the machine checks itself on the basis of what it is told is a correct "reference sample" value, then what happens if the 'reference sample' is actually less than reported? Every breath sample thereafter will be skewed upward.

The way officers give the test is suspect. Many years ago, it turned out that there was a hole in the back of an older version of the Intoxilyzer that, when covered, permitted officers to manipulate the breath test results of DWI/DUI suspects. This flaw was fixed. Just recently, it was determined at a court hearing that there is no internal test in the machine to determine whether it is operating at a specific required voltage, leaving the spectrometer vulnerable to testing for the wrong wavelength.

A breathalyzer machine doesn't account for the difference in people's physiology. It assumes a ratio of 2100 to 1 when it relates blood alcohol level to breath alcohol concentration. It is well known that people vary in hematocrit level, which can cause breath alcohol concentration to vary wildly. Further, some people with diabetes, or who are on very low carbohydrate diets or who work around paint fumes may have substances in their breath that will absorb the same wavelength as alcohol in an infrared spectrometer. It has been predicted that mouthwash and tooth implants may cause variance in the way the machine accurately computes breath alcohol concentration.

Should I Take the Breath Test?

When we are asked this question our response is always the same, "Do you feel lucky?" If you refuse a breath test you will be arrested on DWI charges and have your license suspeded for at least 180 days.

However, what if the machine is wrong the only time it tests you? In our opinion the machine does not always accurately quantify the amount of alcohol in a person's blood. In deciding whether to take the test, you must consider the possibility that you will be providing the State inaccurate and damning scientific evidence of guilt.

If you believe your Texas breathalyzer results may have been flawed, contact Stradley, Chernoff & Alford, L.L.P. to schedule a consultation regarding your Texas DUI/DWI arrest.