Blood Test

In a blood test case, the prosecutor will often present testimony of the senior toxicology analyst at the medical examiner's office and the lab manager in that same office, who performed the laboratory tests on the blood specimen and determined the presence of drugs, a blood THC level, or a blood alcohol concentration (BAC) level.

The toxicology analyst will often testify about their qualifications to conduct the tests and provide testimony about familiar with the protocols involved in administering the tests. The toxicology analyst will often testify about the test methods used were commonly used and accepted within the scientific community.

You also need a DWI defense attorney experienced in fighting to exclude the blood test results from trial and explaining problems with blood testing if the results are admitted at trial.

Attorneys for DWI Blood Testing in Tarrant County, TX

The criminal defense attorneys at Law Offices of Richard C. McConathy in Fort Worth are experienced in fighting DWI cases involving a blood test. We can help you determine whether the blood test should be excluded because the sample was seized or tested in an unreasonable manner.

We can also help you understand the problems with using blood testing to estimate the alcohol concentration of the sample as an indicator of impairment in a DWI case.

Call our experienced Fort Worth DWI defense attorneys to discuss your pending charges, the potential penalties that apply to that charge, and the most effective ways to fight the case.

Call (817) 422-5350 today.


Defense Challenges to the DWI Blood Test

The criminal defense attorney in a DWI blood test case will often object before and at trial to the admission of the blood evidence because the results lack a sound and reliable foundational basis. Objections to the breath test will often center around a showing that the blood test results were not scientifically reliable or based on sound scientific theory because of problems with the testing methods or the maintanance of the equipment using during the subjects testing.  

The defense attorney might also raise objections to the qualifications of the emergency room nurse at the hospital who took the defendant’s blood specimen or show that less than sanitary procedures were used for taking the sample as required by Section 724.017 of the Transportation Code. 

The attorney will also make objections to the qualifications of the toxicology analyst to perform the tests and challenge the methods used to conduct the tests or their knowledge of those methods.


Scientific Reliability of Blood Testing in a DWI Case

In blood test cases, the DWI defense attorney will often argue that the State failed to demonstrate the test results were scientifically reliable or based on sound scientific theory. In order for scientific evidence to be admissible at trial, it must be considered sufficiently reliable as to be of help to a jury. Scientific evidence must typically meet three criteria to be admissible:

  1. the underlying scientific theory must be valid;
  2. the technique applying the theory must be valid; and
  3. the technique must have been properly applied on the occasion in question.

In the context of blood test evidence, Section 724.064 of the Texas Transportation Code provides that at the trial of offenses under Chapter 49 of the Penal Code, which includes DWI, “evidence of the alcohol concentration or presence of a controlled substance, drug, dangerous drug, or other substance as shown by analysis of a specimen of the person's blood, breath, or urine or any other bodily substance taken at the request or order of a peace officer is admissible.” TEX. TRANSP. CODE ANN. § 724.064.. 

By enacting Section 724.064, “the Legislature has already determined that the underlying science is valid, and that the technique applying it is valid as long as it is administered by individuals certified by, and using methods approved by the rules of [The Department of Public Safety].” Reynolds v. State, 204 S.W.3d 386, 390 (Tex.Crim.App. 2006). For instance, in Mireles v. Texas Dept. of Pub. Safety, 9 S.W.3d 128, 131-32 (Tex. 1999), the court found that the Texas Legislature has statutorily recognized the scientific theory and technique behind chemical tests of the breath or blood.

As a result blood specimen test results are admissible even without proof that the underlying scientific theory is reliable. Garcia v. State, 112 S.W.3d 839, 848 (Tex.App.–Houston [14th Dist.] 2003, no pet.). Nevertheless, in a DWI blood test case, the State must show that the blood specimen was taken by a qualified person, such as a “registered professional nurse” or a “licensed vocational nurse.”

The prosecutor with the District Attorney's Office must also show that the blood sample was taken in a “sanitary place.” TEX. TRANSP. CODE ANN. § 724.017. The courts have also found that for evidence of blood-alcohol concentration to be admissible, there must be evidence showing compliance with the requirements of Section 724.017. 

Also, in order to meet the requirements of Rule 702 of the Texas Rules of Evidence, the State must demonstrate that “the specimen was taken and analyzed by individuals who are certified by, and were using methods approved by the rules of [the Department of Public Safety]” and that the technique was properly applied in accordance with the department's rules on the occasion in question. Reynolds, 204 S.W.3d at 390-91.

These requirements for blood testing in Texas may be met by evidence that the person who performed the test “knows the protocol involved in administering the test and can testify that he followed it on the occasion in question, [but] he need not also demonstrate any personal familiarity with the underlying science and technology.” Id. at 391.

Even if the DWI blood test results showing an alcohol concentration are admitted, your criminal defense attorney can show problems with the way the sample was taken, stored, and tested.


Common Ways the DWI Attorney Attacks on Blood Evidence

The criminal defense attorney's main priority in these cases is finding a way to get the legal or medical blood test results excluded from evidence. For DWI cases in Texas, the most common attacks against the blood evidence can include:

  • The blood sample was not properly refrigerated before the testing - the experts agree that it is important to refrigerate the blood sample continuously after the sample is taken and until the BAC testing is performed. The results can be attacked if the law enforcement officer stored the sample in a hot vehicle or evidence storage unit for an extended period of time before the testing; 
  • Yeast, microbes or other contaminants created alcohol in the sample - The the blood sample is not properly drawn or stored then microbes or yeast can interact with the sample in a saw that causes the sample to generate additional alcohol; 
  • The vacutainer tube was expired - your criminal defense attorney will inspect the vials and packaging of the blood draw kit to inspect the grey top vacutainers to determine the expiration date. If the tube is expired, then the vacuum can be compromised and contamination can occur. 
  • The vial with the grey top was not rotated property - experts agree that blood alcohol collection in grey top vials recommend that the vial be rotated eight (8) times after the sample is collected so that the blood is mixed with the preservative and anticoagulant powders in the vials. In fact, the requirement for eight rotations is listed on the "Blood Withdraw Form." 

Blood Test Documents in an Intoxication Case

In a DWI case, the prosecutor will often use blood test documents to seek the admission of the results of blood alcohol concentration testing at trial. Your attorney can also inspect the evidence and learn more about how it was drawn, analyzed and stored.

Before any hearing or trial, your criminal defense attorney will carefully review all documents related to blood testing including:

  • any test for the presence of drugs or a comprehensive screen plus all necessary documentation mentioned if the test is done by a different facility; 
  • the results of any test in a laboratory report; 
  • the name of any testing agency; 
  • the names of any technician or criminalist who did the testing; 
  • the name of the nurse or technician who drew the blood; 
  • the chain of custody; 
  • the blood test checklist; and 
  • the DIC warning sheet.

Blood Withdraw Procedure Form in Texas

The following "blood withdraw procedure form" is used in Texas DWI Blood Test cases. 

  • the officer placed the suspect under arrest for a Chapter 49 offense involving the operation of a motor vehicle;
  • The officer read DIC-24 to the suspect and did provide the suspect with a written copy of the form;
  • The suspect did consent, refused to give a blood sample or was incapable of refusing or unconscious;
  • The officer did remove the vial from the blood collection kid;
  • The expiration date on the blood kit / vial was listed as ________;
  • The officer did fill out the label that came with the blood kit completely except for the time the blood was drawn;
  • The vial was closed when handed to the nurse;
  • A preservative or anti-coagulate power was seen in the vial; 
  • The nurse or technician did the following when withdrawing the blood from the suspect:
    • used betadine or another equivalent and specified solution to disinfect the arm;
    • saved the swab packaging;
    • rotated the vial as indicated in the directions 8 times so as to mix blood with preservative anti-coagulant; and
  • The vial top was never opened and was then delivered to the officer and the officer finished completing the label by adding the time the blood was drawn and the officer and nurse / technician used his or her initials on the label, which was used to seal the vial top closed. 

The form is signed by both the arresting officer and the nurse or medical technician, the time of the blood draw, and the suspect's name and the offense number. 


This article was last updated on Monday, April 24, 2017.