Dallas DWI Lawyer Blog | Attorney

In most DWI breath test cases, the State will attempt to convince the jury to find a person guilty based on a failed breath test.  In every one of these cases the State will use a breath test that was given some time after the arrest was made. 

It is important to remember that officers DO NOT HAVE scientifically valid breath test machines in their vehicles when they make an arrest for DWI.  Instead, the officer must transport the citizen accused of DWI to what is known as the "intoxilyzer room" which is usually located in a city or county jail.  The length of time between an arrest on the side of the road and a breath test score that is given in an intoxilyzer room is an important factor in EVERY DWI breath test prosecution.

The law requires that the state must prove a person was intoxicated AT THE TIME OF DRIVING, not 30 minutes, one hour or in many cases even longer when he or she gives a breath test at a jail facility.  In order to relate a failed breath test back to the time of driving, a State's expert must use what is known as Retrograde Extrapolation.

Retrograde Extrapolation is the scientific process used to take the score of a breath test and then back it up in time to show what a person's BAC was when they were driving.  However, in order to properly calculate usuing retrograde extrapolation the State's expert needs to know the following information:

1. The person's gender;
2. Their weight;
3. The time they had their first drink;
4. The time they had their last drink;
5. The time of the stop (arrest);
6. The type of alcoholic beverage consumed;
7. The type of  food a person ate and when they last ate;
8. The time the breath test was given;
9. The result of the breath test.

Often time, the state does not have all of the information for their expert to properly retrograde a breath test result to the time of driving.  In these cases a successful argument can be made by the defense attorney that the State did not satisfy its burden of proving that the citizen accused was intoxicated at the time they were operation a motor vehicle, and therefore, they should be found NOT GUILTY of driving while intoxicated.

It is important to do a thorough review of the police report and video of a DWI investigation to determine if the State will have problems with retrograde extrapolation in a DWI breath test case.  This is one of the most successful defensive arguments and can, in some cases, lead to a not guilty verdict.

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Did you know that those new braces, veneers, bridge or even cap may cause you to fail a breath test?  It is true!

Dental appliances can be a major factor in high breath test results. Like GERD defenses, dental issues concern mouth alcohol. If a person fails a breath test, and has had major dental work, this defense should be explored.

Dental appliances include, but are not limited to: braces, retainers, mouth expanders, bridges and false teeth or dentures. These appliances provide an opportunity for food to become trapped in the mouth after eating. Anyone who has had extensive dental work, such as braces, will tell you that getting food trapped in their teeth is a persistent problem.

When food is trapped within the teeth and alcohol is consumed, portions of the alcohol may become trapped in the teeth or dental appliance. Upon taking a breath test, breath is blown back through the mouth and alcohol molecules can be picked up by the expired breath before introduction into the machine. When this occurs, a false positive test for alcohol may be obtained.

Some studies have demonstrated that some dental adhesives can trap alcohol in ones mouth for up to one hour. A 15-20 minute waiting period before a breath test can be administered does not eliminate this problem.

There has been insufficient testing on subject who had both consumed and absorbed alcohol in their system with certain dental appliances to truly know the magnitude of the effect of the dental appliance. Therefore, a dental appliance problem can escape detection by the traditional slope detector on the machine. A “disconnect defense” may be available for a defendant who has dental issues, a high breath test and a “sober” video.

Note: The above article also appears in our Collin County DWI Blog.

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The Tyndall Effect is a physics concept used to discuss something known as “colloidal suspensions.”  Colloidal suspensions describe a homogenous substance consisting of submicroscopic particles dispersed in another.  Unlike solutions, colloidal suspensions exhibit light scattering.  A beam of light or laser, invisible in clear air or pure water, will trace a visible path through a genuine colloidal suspension, e.g. a headlight on a car shining through fog.  This is knows as the Tyndall effect (after its discoverer, British physicist John Tyndall), and is a special instance of diffraction.  Diffraction is a phenomenon that occurs with gases and liquids.

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One can do a quick search on Google concerning the Intoxilyzer 5000 and discover that there is a great volume of internet literature concerning the many scientific problems with the machine used in Texas to measure a person’s breath/alcohol concentration. As an attorney dedicated to DWI/DUI defense I have spent numerous hours researching issues concerning the performance, or lack there of, of the Intoxilyzer machine. Below, are the 5 major issues concerning the performance of the Intoxilyzer 5000.

The 5 things that can have a major affect on the machines performance are: 1) Chemical Exposure; 2) Air Bags (aka the Tyndall Effect); 3) Atkins or low carb diets; 4) Gastro Esophageal Reflux Disorder (GERD); and 5) Dental Issues.

The first three (chemical exposure, Tyndall Effect, and Atkins or low carb diets) are problems based on interferents that may not be detected by the Intoxilyzer 5000. The last two relate to “mouth alcohol” which is increased alcohol laden breath results based upon gastro esophagus disorder and dental issues.

To read more about these 5 major issues that may affect the result from an Intoxilyzer 5000 click on the links below:

Chemical Exposure
Air Bags (aka Tyndall Effect)
Atkins or low carb diets
GERD
Dental Issues

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A  common misconception among the public is that if a person gives a breath test that is under the legal limit (0.08) then that person will not be charged will DWI.  WRONG!  See the article below from my other DWI blog for an explanation.

If I give a breath sample under 0.08 the officer will let me go, Right? WRONG! By Plano DWI Lawyer Troy P. Burleson

If you are suspected of drunk driving, you will probably be asked to give a sample of your breath to determine your alcohol concentration. The question most people ask is, "If I give a sample under the legal limit of 0.08, will the officer let me go?” The answer is NO. Even if you give a breath sample below the legal limit of 0.08, you will still be charged with DWI.

Under Texas law, the prosecutors can prove that you were intoxicated by proving:
1) You lost the normal use of your mental faculties; OR
2) You lost the normal use of you physical faculties; OR
3) You had an alcohol concentration of 0.08 or more.

The “Or” in the above law means that the State only has to prove one of the elements above not two or all three. If you give a breath sample under the legal limit, the State will argue that you have a low tolerance for alcohol, you had other substances in your system besides alcohol, or that you had “sobered up” during the time that elapsed between your arrest and the time you gave a breath sample.

Before you are asked to give a breath sample, the officer must read what is known as you “DIC” warnings to you. This warning, which explains the consequences or giving or not giving a breath sample, states out by stating, “You are under arrest…” That means that the office has already decided to ARREST YOU BEFORE you give a breath sample.

Many people are shocked to discover that an officer will still arrest a citizen if they give a breath sample under the legal limit. But, officers will testify to the truth of that statement. So, if you are going to be charged with DWI regardless of what you blow, why would you take he chance on a breath machine that is not universally accepted in the scientific community?

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I have written extensively on my Collin County DWI blog about the current law enforcement trend toward mandatory blood testing on citizens accused of drunk driving. Many of our clients ask questions about the legality of forcing citizens to give a blood sample. Although the current state of Texas Law allows law enforcement to obtain a blood warrant to forcible extract a sample of your blood, I along with man other defense attorneys and legal scholars share the belief that this police is against established Texas law and United States Constitutional law.

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