Breath tests are frequently requested by officers during a DWI investigation in Galveston, Texas. There are two types of breath tests an officer can request, and they differ significantly in their accuracy and admissibility in court.

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Portable Breath Tests

If you were arrested after agreeing to a breath test, one of the first questions we would ask you at Galveston Criminal Defense Attorneys PLLC is where the test was conducted. If it happened on the side of the road, the officer likely administered a PBT or "portable breath test."

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Portable breath tests are handheld devices that you blow into, which then provide a reading of your breath alcohol content. This testing method has not been approved for admission as evidence in Texas courts. Rule 702 of the Texas Rules of Evidence requires all scientific evidence to be reliable. The evidence collection process must be reliable in general and correctly applied on the particular occasion. These strict requirements cannot be met for a portable breath test.

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In Cox v. State, the prosecutors didn't even attempt to meet the requirements of TRE 702.

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"Nothing at all was offered to explain how the SOBERLINK machine operated, how it measured breath-alcohol content, how it generated or recorded the test results, or how the reliability of these test results could be measured. We have found nothing to establish that the science behind the SOBERLINK method of acquiring data 'has been widely accepted in a sufficient number of trial courts through adversarial gatekeeping hearings.' See Somers v. State, 368 S.W.3d at 536." Cox v. State, 446 S.W.3d 605, 609 (Tex. App. 2014).

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Intoxilyzer 9000

The type of breath test admissible in court is one conducted with an Intoxilyzer 9000. In Harris County, these machines are kept at jail facilities and are only used after a DWI arrest has been made. The first step in a breath test case is for the officer to make the arrest and then read a form called the DIC-24. The DIC-24 informs the person under arrest that they are under arrest and that if they refuse to provide a breath or blood sample as requested by the officer, their driver's license will be suspended.

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Many people consent to a breath test out of fear that their license will be revoked. Galveston Criminal Defense Attorneys PLLC can help you protect your driver's license and fight DWI charges in Galveston, Texas.

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The Intoxilyzer 9000 is the latest version of a proprietary machine that takes a breath sample and uses the presence of alcohol mixed with alveolar breath to produce a reading. The process of creating and calculating this number is a trade secret of the company that owns the Intoxilyzer 9000 and is not available for public release.

The machine is usually attached to a large wooden box that locks and stores the Intoxilyzer. When a breath sample is taken, the officer asks the person to breathe into a mouthpiece where the air travels down a tube and into a chamber where a light is shined through the air. The theory behind the Intoxilyzer is that alcohol particles block part of the light that passes through, and the amount of light received is proportional to the amount of alcohol in the person's breath. To ensure the machine is functioning correctly, it self-tests by extracting a liquid mixture of alcohol and pushing it through the instrument. The Intoxilyzer is programmed to know the expected level of this alcohol mixture and compare it to the result. If the tolerance of this expected value is off, the test will not complete, and the machine will refuse to print a result. That mixture must be kept at 33.80 - 34.20° Celsius.

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Defeating a Breath Test Case

Breath test cases are easier to contest than blood test cases. This is because jury trials involve 6 or 12 community members who have likely had blood tests for medical reasons but have never been asked by a doctor to "blow into this" for a diagnosis.

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The process is unfamiliar and full of complexities that the State must prove were executed flawlessly for the test to be reliable beyond a reasonable doubt. Most challenges to a breath test case start with the traffic stop and determining if the police had reasonable suspicion to begin an investigation. If they didn't, it doesn't matter how well the testing went; the results will be inadmissible.

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Other challenges include improper administration of the test, using faulty equipment, failing to observe the required 15-minute waiting period, not accounting for burps or the use of mouthwash, and more. You don't have to keep worrying about your case. Call us today for a free consultation and get started on your defense.