2591 Dallas Parkway, Suite 207, Frisco, TX 75034

888-DWI-FRISCO [469-333-3333]

The Law Offices of Hunter Biederman, P.L.L.C.



Collin County DWI AttorneyLaw Enforcement Agencies in Texas that conduct Breath Testing use a machine called the Intoxilyzer 5000.

Here are some interesting facts that you might not have known about the breath test that you took. These are just SOME of the facts that I could show the jury in your case:

There are currently only two models of the Intoxilyzer 5000 in use in Texas, the Model 68 and the newer Model 68 EN. These two models are “upgrades” to the prior model 64, and 66 machines.

The Intoxilyzer 5000 is a computer based on old technology. The brains of this machine is a Z-80 microprocessor which was introduced 30 years ago in 1975. The Z-80 microprocessor was the basis for some of the very first home computers, and video games, in the early 1980's. As a matter of fact, the Z-80 chip is the same chip that ran the old Atari video games.

The breath testing device used in Texas is the Intoxilyzer 5000. This is the only Breath Test that can be potentially used against you in a Texas Court. (This should not be confused with the PBT - Portable Breath Test) Shown below is a PBT.

The Intoxilyzer 5000 works on the theory of infrared absorption. The machine has a light source (light bulb (1)) positioned at one end of the sample chamber (5). There are filter wheels (6) at the end of the cylinder and on the other side of these filter wheels is a light receiver (7).

AFTER a person is arrested for DWI, an officer will ask them to blow into a breath tube which leads to a breath sample chamber. The machine shines a light source (a light bulb) through this sample chamber. The filter wheel spins at the other end of the breath tube chamber. The infrared light causes the alcohol molecules to "vibrate" or "absorb" light at a particular frequency. The filter wheels are “designed” to filter out potential contaminants. The machine filters out some contaminants better than others.

The amount of the breath sample and any reading of alcohol are very minute. (Between 81.4 ml and 82.2 ml). The machine must make a multiplication conversion to an amount great enough for us to understand. The difference in light emitted and received is computed through a computer program in the machine to come up a value that can be compared to a .08. The conversion the machine makes on the differences in light would be the equivalent of taking the paper towel tube and increasing its size to that of a 55 gallon drum! Any error would then be exaggerated by that amount.

Can You Trust The Intoxilyzer Number?

There is much debate about the accuracy of the Intoxilyzer 5000. The State’s expert will state that the machine will only read light absorbed by alcohol, while we now know that the machine often misreads as alcohol other commonly found substances in the breath, thus giving an inaccurate high reading.

Texas law only requires that the Intoxilyzer 5000 perform within a plus or minus 10% accuracy rate. This means that a 20% variance is acceptable. For example, when the machine is checked for proper function and accuracy and the Breath Test Technician uses a .08 alcohol solution, the machine is judged to be functionally properly, if the results are within 0.072 and 0.088.

An everyday example is if you are stopped and arrested for DWI and take a breath test, and you blow a 0.080, when your actual alcohol content is something less, you still face the charge of driving with a .08 or higher. Very Scary.

The manufacturer does not warrant the Intoxilyzer 5000 for any particular purpose. The machine is not warranted for accurate and reliable breath testing.

The Intoxilyzer also assumes that everyone tested will have a blood/breath ration of 2100/1 (i.e. 2100 parts of alcohol in the breath for every 1 part of alcohol in the blood). If a person has a higher blood/breath ratio (i.e. 2400/1) the test will not be adversely affected by this assumption. However a person with a lower blood/breath ratio will be adversely affected because the Intoxilyzer will erroneously read too high, thus a person who should test at .05 or .06 could actually test well above a .08 Additionally, scientists have documented people with blood/breath ratios as low as 1100/1.

A person with a fever will have a higher breath test reading than an identical person without a fever. Therefore, the temperature of your body can affect what the Intoxilyzer reads, and your body temperature has nothing to do with the amount of alcohol you may have or have not consumed.

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