Testing Procedures in Dallas DWI

Generally, in the Dallas area, when you’re taken to the police station after being pulled over for driving while intoxicated (“DWI”), you’ll be asked to take a breath test on the Intoxilyzer 5000 EN machine.  If you refuse to submit to a breath test, the officer may request a blood sample.  If you refuse to give a blood specimen, the officer can obtain a warrant that is signed by a judge allowing a qualified person to remove blood without your consent.

Mandatory DWI Blood Tests

As of September 1, 2009,  Chapter 724 of the Texas Transportation Code requires an officer to draw blood without a warrant if:

  1. the subject, arrested for an offense under Penal Code Chapter 49, refuses to provide a breath sample and a person other than the suspect “has suffered bodily injury and has been transported to a hospital or other medical facility for medical treatment”;
  2. the suspect is arrested for DWI with a child passenger under Penal Code §49.045;
  3. the officer credibly believes that the suspect can be charged with felony DWI due to two prior Chapter 49 DWI offenses or one prior intoxication manslaughter; or
  4. the officer credibly believes that the suspect committed DWI and was previously convicted of intoxication assault or DWI with a child passenger.

Is DWI Blood Testing Reliable in Texas?

Although more precise results can be obtained from blood testing than breath testing if done properly, blood analysis sometimes is not perfectly accurate. There are several ways an error could cause the blood test results to be erroneous.

Potential errors that may be present during the process of DWI blood testing:

  1. The person who drew the blood was not qualified – The Prosecution has the burden to prove the qualifications of the person drawing blood.  In non-search warrant cases, the Transportation Code lists several qualified professionals that must be used: a physician, qualified technician, chemist, registered professional nurse, or licensed vocational nurse. Tex. Trans. Code §724.017(a).  With DWI Blood warrant cases, this section does not control; however, the Prosecution must qualify the person drawing blood and prove that the evidence was obtained in a medically acceptable fashion.
  2. Chain of custody issues- If the prosecution is unable to prove this in court, the blood sample may be ruled inadmissible and prevented from being used as evidence at trial.
  3. Contamination – if the skin is swabbed with something that contains 2% ethyl alcohol.
  4. Blood sample is compromised– If the blood lab tube is not properly sealed or stored, if blood is exposed to heat, if the lab tube is contaminated, or the blood is contaminated by some outside source.
  5. Improper draw or improper administration of blood test.
  6. Technical errors – If the person in charge of testing the blood in the lab does not follow the proper testing procedures or delays in analyzing the blood sample, either of these errors may make the blood results incorrect.
  7. Failure to mix blood sample with anticoagulant and preservative.
  8. Unqualified blood test analyst – If too much time passed between when the defendant was driving and when the blood sample was obtained.
  9. Mislabeling of blood sample – If it was mislabeled, the results could be from another person’s blood sample.
  10. Unsanitary place where blood was obtained – If a blood draw was made without a warrant pursuant to the Transportation Code, the place the blood was drawn must be a “sanitary place.” Tex. Trans. Code §724.017(a) In search DWI blood test warrant cases, it is not required to show a sanitary place where the blood was obtained; however, the Prosecution must show that the blood was drawn in a medically acceptable fashion.
  11. Testing equipment is not working properly – If a good blood specimen is tested by a machine that is not functioning, it may cause the blood results to be erroneous.

Dallas DWI Blood Test Warrant Defenses

If you refused to give breath or blood and the police officer obtains a warrant to withdraw your blood, the following may be additional legal defenses to use:

  1. The affidavit is insufficient to establish probable cause – Police officers must articulate their probable cause that the defendant committed DWI in the affidavit. The elements that must be shown in the four corners of the affidavit are: 1) operated, 2) a motor vehicle, 3) in a public place, and 4) while intoxicated.
  2. The person who drew the blood was not qualified – In warrants cases the State must qualify the person drawing blood and prove that the evidence was obtained in a medically acceptable fashion.
  3. The affidavit contains conclusory statements – If there is not enough detail, then the warrant should be suppressed, therefore any blood test results obtained from the DWI blood warrant are not able to be used at trial. Jones v. State, 833 S.W.2d 118 (Tex. Crim. App. 1992)
  4. The warrant or probable cause affidavit did not include a time reference and is stale -Staleness of the warrant is covered by statute. The warrant must be executed “without delay.” Tex. Code Crim. Proc. Art. 18.06 The warrant must have the “date and hour of its issuance. Tex. Code Crim. Proc. Art. 18.07(b)

To speak to our aggressive Dallas DWI lawyer, Murray L. Bristol, please call (214) 880-9988, or use the contact form on this page, and he will contact you promptly for a free consultation.