DWI Breath Test

After an arrest for DWI, the arresting officer will often request that the driver submits to a breath test to determine its alcohol content. The prosecutor will then attempt to use that breath test reading at trial in order to prove that the defendant is guilty of DWI.

In many DWI breath test cases, the defense will raise an issue of fact concerning compliance with the DPS rules for taking a breath specimen. In those cases, the court should instruct the jury on the issue, if requested, pursuant to the exclusion rule in CCP 38.23. See Atkinson v. State, 923 S.W.2d 21 (Tex.Crim.App. 1996). The current regulations for breath testing are found at 37 Tex. Admin. Code §19.4(c).

In a breath test case, the criminal defense attorney will often file motions to show the court that the breath test machine or the testing method used did not comply with DPS rules. Even if the court does not suppress or exclude the breath test reading before trial, the criminal defense attorney can request a special jury instruction on the issue of compliance with rules for taking a breath specimen.

Attorney for the DWI Breath Test in San Antonio, TX

If you were arrested for DWI and submitted to a breath test with a reading over .08, then contact an experienced criminal defense attorney at Flanary Law Firm, PLLC. Don Flanary is experienced fighting the DWI cases in San Antonio and Bexar County, TX.

Whether you are charged with a first DWI offense or a more serious offense for a second or subsequent conviction, Don Flanary can help. He also represents clients charged with felony DWI-related offenses such as intoxication assault and intoxication manslaughter.

Call (210) 738-8383 today for a free consultation.


Admissibility with of the Breath Test Results at Trial

Section 724.016 sets out the statutory predicate for admissibility of breath tests in Texas. Under this statute, a breath test must comply with § 724.016 before it is admissible.

Texas law provides that a breath test that was not “taken and analyzed under the rules of the department” and that violated the rules of the department is not admissible at trial. See Harrell v. State, 725 S.W.2d 208 (Tex. Crim. App. 1986); Davis v. State, 949 S.W.2d 28 (Tex. App.—San Antonio 1997, no pet.); Atkinson v. State, 923 S.W.2d 21 (Tex. Crim. App. 1996).

Tex. Trans. Code § 724.016 provides:

(a) A breath specimen taken at the request or order of a peace officer must be taken and analyzed under rules of the department by an individual possessing a certificate issued by the department certifying that the individual is qualified to per­form the analysis.

(b) The department may:

(1) adopt rules approving satisfactory analytical methods.


Compliance with Rules for the DWI Breath Test

If the state seeks to introduce the defendant's breath test results from a breath specimen taken after a DWI arrest, the defendant can show a lack of compliance with the rules and regulations required for such testing.

Upon request, the jury will be instructed that before it may consider the results of any test of a specimen of the defendant's breath, the jury must find beyond a reasonable doubt that the regulations of the Texas Department of Public Safety were complied with in administering the test. The jury might then be told about each of the regulation of the Texas Department of Public Safety including:

  • a period during which an operator is required to remain in the presence of the subject - an operator shall remain in the presence of the subject (although direct observation is not required to ensure the validity or accuracy of the test result) at least 15 minutes before the test and should exercise reasonable care to ensure that the subject does not place any substances in the mouth;
  • the breath alcohol testing instrument and reference sample device must be operated by either a certified operator or technical supervisor and only certified personnel have access to the instrument;
  • the use of a system blank analysis in conjunction with the testing of each subject;
  • the analysis of a reference sample, the results of which must agree with the reference sample predicted value within plus or minus 0.01g/210 L, or such limits as set by the scientific director;
  • the reference analysis shall be performed in conjunction with subject analyses;
  • all analytical results shall be expressed in grams of alcohol per 210 liters of breath (g/210L);
  • maintenance of any specified records designated by the scientific director;
  • supervision of certified operators and testing techniques by a technical supervisor meeting the qualifications required by the Department (relating to Technical Supervisor); and
  • the designation that the instrumentation will be used only for testing subjects that are suspected of violating any statute or rule that defines intoxication in terms of alcohol concentration; and in compliance with the requirements of the Department relating to Operator Certification. 

The jury can also be instructed at trial, if the proper request is made, that if the jury finds beyond a reasonable doubt that all of these requirements were complied with, then the jury may consider the results of the test in its deliberations. But if the jury did not find, or if the jury has a reasonable doubt as to the compliance, then the jury may not consider said test or its results for any purpose and shall not consider it whatsoever in arriving at its verdict.


Additional Resources

Standard Operating Guidelines for Evidential Breath Alcohol Instrument Calibration - Visit the Texas Breath Alcohol Testing Program, Office of the Scientific Directory to find the Directive from the Scientific Directory at OSD-CAL-O1, Version 6. The SOGs describe the procedure for breath alcohol instrument calibration and the calculations used to establish the combined uncertainty. Any changes which occur as a result of the implementation of these guidelines apply only to calibrations which are completed on or after the effective date of this document.


This article was last updated on Friday, January 20, 2017.

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