Breath tests are often requested by officers in a DWI investigation in Houston, Texas.  However there are two types of breath tests that the officer can request and they vary greatly in both their accuracy and their 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 Houston Criminal Defense Attorneys PLLC is where did the test happen?  If it happened on the side of the road then the officer most likely gave you what is called a PBT or "portable breath test."  

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Portable breath tests are hand held devices that you blow into and then produce a reading of a certain breath alcohol content.  This method of testing has not been approved for admission into evidence at a jury trial in Texas courts.  Rule 702 of the Texas Rules of Evidence requires all scientific evidence to be reliable.  Not only does an evidence collection process have to be reliable in general, it has to have been applied correctly on the particular occasion in question.  These strict requirements cannot be met for a portable breath test.  

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In Cox v. State, the prosecutors didn't even give it a go to try 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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Intoxylizer 9000

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The type of breath test that is admissible in court is one taken from an Intoxylizer 9000.  In Harris County these machines are kept at jail facilities and are only used after a DWI arrest has already 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 in fact under arrest and that if they refuse to provide a breath or blood sample as requested by the officer that their driver's license will be suspended.  ​

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Many people consent to a breath test under the fear that their license to drive will be revoked.  Houston Criminal Defense Attorneys PLLC can help you save your driver's license and fight DWI charges in Houston, Texas. 

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The Intoxylizer 9000 is the latest version of a proprietary machine that take a sample of breath and uses the presence of alcohol mixed with alveolar breath to produce a number.  This number and how it is created and calculated is a trade secret of the company that owns the Intoxylizer 9000 and is not available for public release.  

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The machine is normally attached to a large wooden box which locks and stores the Intoxylizer.  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 Intoxylizer is that alcohol particles block part of the light that goes through and how much light is received is proportional to the amount of alcohol in the persons breath.  To make sure that the machine is working correctly it self tests by extracting a liquid mixture of alcohol and pushes it through the instrument.  The Intoxylizer is programed to know the expected level of this alcohol mixture and compare this to the result.  If the tolerance of this expected value is off then the test will not complete and the machine will refuse to print a result.  That mixture has to be kept at 33.80 - 34.20° celcius.

Defeating a Breath Test Case

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Breath Test cases are easier to win then blood test cases.  This is because jury trials are tried to 6 or 12 members of the community who many times have gotten a blood tests to determine something medically wrong with them.  None of them have ever been to the doctor and had the doctor tell ​them, "Great we just need to run a few tests now blow into this."​

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The process is unfamiliar and riddled with complexities that the State must show went so well that the test is 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 then it doesn't matter how well the testing went the results will be inadmissible.  

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Other challenges include failure to properly administer the test by using faulty equipment, failing to wait the appropriate 15 minute waiting period, failing to account for burps and the use of mouthwash, and many more.  You don't have to keep wondering and worrying about your case.  Call us today to get a free consultation and get started on your defense.