DWI Blood Draws

It is now common practice for Fort Worth police officers to ask you to consent to a blood test or force you to take one. Most other police departments in Tarrant County will do the same. City judges are on the job at all hours of the night to sign the warrant if you refuse.

This article details some of the issues that come up when blood is drawn. This is a surface level discussion of the issues a good DWI attorney must tackle. For how blood is actually tested, see the article on Blood Testing. Of course, chemical tests performed to prosecute DWI cases are not just blood tests. See the article on DWI Breath Tests and also the Science of Breath Testing.  

Texas law states that a blood draw must be conducted in a sanitary place, and that only a physician, qualified technician, chemist, registered professional nurse, or licensed vocational nurse may administer DWI blood draws. There are many procedures which police and medical personnel must follow when taking DWI blood draws, and likewise there many ways that defendants can challenge the accuracy. Section 724.017 of the Texas Transportation Code outlines the procedure for the taking of a specimen:


(a) Only the following may take a blood specimen at the request or order of a peace officer under this chapter:

(1) a physician; 

(2) a qualified technician; 

(3) a registered professional nurse; 

(4) a licensed vocational nurse; or

(5) a licensed or certified emergency medical technician-intermediate or emergency medical technician-paramedic authorized to take a blood specimen under Subsection (c). 

(a-1) The blood specimen must be taken in a sanitary place. 

(b) If the blood specimen was taken according to recognized medical procedures, the person who takes the blood specimen under this chapter, the facility that employs the person who takes the blood specimen, or the hospital where the blood specimen is taken is immune from civil liability for damages arising from the taking of the blood specimen at the request or order of the peace officer or pursuant to a search warrant as provided by this chapter and is not subject to discipline by any licensing or accrediting agency or body. This subsection does not relieve a person from liability for negligence in the taking of a blood specimen. The taking of a specimen from a person who objects to the taking of the specimen does not in itself constitute negligence and may not be considered evidence of negligence.

(c) A licensed or certified emergency medical technician-intermediate or emergency medical technician-paramedic may take a blood specimen only if authorized by the medical director for the entity that employs the technician-intermediate or technician-paramedic. The specimen must be taken according to a protocol developed by the medical director that provides direction to the technician-intermediate or technician-paramedic for the taking of a blood specimen at the request or order of a peace officer. In this subsection, "medical director" means a licensed physician who supervises the provision of emergency medical services by a public or private entity that:

(1) provides these services; and

(2) employs one or more licensed or certified emergency medical technician-intermediates or emergency medical technician-paramedics.

(c-1) A protocol developed under Subsection (c) may address whether an emergency medical technician-intermediate or emergency medical technician-paramedic engaged in the performance of official duties is entitled to refuse to:

(1) go to the location of a person from whom a peace officer requests or orders the taking of a blood specimen solely for the purpose of taking that blood specimen;

(2) take a blood specimen if the technician-intermediate or technician-paramedic reasonably believes that complying with the peace officer's request or order to take the specimen would impair or interfere with the provision of patient care or the performance of other official duties; or

(3) provide the equipment or supplies necessary to take a blood specimen.

(c-2) If a licensed or certified emergency medical technician-intermediate or emergency medical technician-paramedic takes a blood specimen at the request or order of a peace officer, a peace officer must:

(1) observe the taking of the specimen; and

(2) immediately take possession of the specimen for purposes of establishing a chain of custody.

(d) A person whose blood specimen is taken under this chapter in a hospital is not considered to be present in the hospital for medical screening or treatment unless the appropriate hospital personnel determine that medical screening or treatment is required for proper medical care of the person 

What is The Risk of Contamination?

Bacteria can compromise a blood sample and distort the accuracy of DWI blood draws if the area from which the blood is drawn is not properly disinfected. Betadine solution is the reddish-orange looking topical solution you’ve probably seen. It is applied to disinfect the skin before blood is drawn. The proper technique involves swabbing the area in a spiral motion of concentric circles to force bacteria away from puncture site. Often the solution is applied incorrectly in back-and-forth motion, opening the door to contamination.

Fungus On the Skin Can Create False High Readings

Fungus is another source of contamination, and fungus is more difficult to kill than bacteria. Candida Albicans is fungus that is present on human skin and grows as a yeast. If Candida Albicans gets into the blood tube it can produce ethanol if it is mixed with sodium fluoride. Sodium fluoride powder is present in the blood tubes as a preservative! This will create falsely high BAC readings and will contaminate DWI blood draws.

DWI Blood Draws: Blood Tubes

DWI Blood Tests

Vacuum Pressure of the Tube

There are ways to challenge the integrity of the blood tubes, which are sealed and sterile when they leave the manufacturer. BD is the medical technology company which manufactures the gray topped tubes used in DWI blood draws. Each tube has enough vacuum pressure to draw 10 milliliters of blood. If a tube does not draw 10 milliliters of blood it may indicate that the vacuum tube has been compromised and may be contaminated with yeast or bacteria. The expiration date printed on the tube applies to the vacuum tube and not the chemicals.

Your Blood is Delicate!

Each gray topped BD tube has 100mg of preservative sodium fluoride and 20 mg of anti-coagulant potassium oxalate. Once the blood is drawn into the tube, the blood must be immediately mixed with these chemicals. This process is called an inversion. Inversion consists of delicately turning the tube upside down between 8-10 times. The red blood cells are easily broken, and shaking the tube will compromise the test.

DWI evidence is technical and complex. It is essential that you retain a DWI attorney who has the skills to challenge it.


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