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Errors in DWI Blood Tests

The blood alcohol concentration (BAC) of alleged offenders is typically measured through breath tests in a majority of driving while intoxicated (DWI) arrests. In certain cases, police may attempt to get motorists to submit to blood draws for the purposes of measuring BAC.

When an alleged offender refuses to submit or is unable to provide a specimen, authorities may attempt to have the blood drawn without the person’s consent. The legality of forced blood draws has been called into question in recent years, but authorities and prosecutors will often attempt to get blood samples submitted into evidence because failed test results are often viewed as some of the most reliable evidence of intoxication for the purposes of obtaining convictions.

Lawyer for Errors in DWI Blood Tests in Dallas, TX

If you were arrested for DWI in North Texas as the result a test of your blood, it is in your best interest to immediately seek legal representation for help determining whether the test was lawfully and properly administered. The Law Offices of Richard C. McConathy represents clients throughout the greater Dallas-Fort Worth area, including Garland, Balch Springs, Richardson, Carrolton, Mesquite, Grand Prairie, Irving, and many other communities.

Richard McConathy and Brian Bolton are experienced criminal defense attorneys in Dallas who can fight to possibly get your criminal charges reduced or dismissed. They can provide a full evaluation of your case as soon as you call (972) 233-5700 to schedule a free, confidential consultation.


Overview of Errors in Texas DWI Blood Tests


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When Blood Tests are Administered in Dallas County DWI Cases

Under Texas Transportation Code § 724.011, all drivers arrested for DWI offense are deemed to have consented to submit to the taking of one or more specimens of their breath or blood for analysis to determine their BAC or the presence of any controlled substances simply by being licensed to drive in the Lone Star State. This law is commonly referred to as “implied consent.”

Texas Transportation Code § 724.013, however, states that a specimen may not be taken if the alleged offender refuses to submit to the taking of a specimen designated by a peace officer. Despite this right to refusal, state law does provide exceptions under which authorities may obtain blood samples.

Under Texas Transportation Code § 724.014, an alleged offender who is dead, unconscious, or otherwise incapable of refusal is considered not to have withdrawn the implied consent. If the alleged offender is dead, a specimen can only be taken by the county medical examiner, the examiner's designated agent, a licensed mortician, or a person authorized by state law to take a blood or breath sample if there is not a county medical examiner for the county.

When alleged offenders refuse to submit to the taking of one or more specimens of their breath or blood, Texas Transportation Code § 724.012 authorizes officers forcibly take the blood of alleged offenders under any of the following circumstances:

  • The alleged offender was the operator of a motor vehicle or a watercraft involved in an accident that the officer reasonably believes occurred as a result of the offense and, at the time of the arrest, the officer reasonably believes that as a direct result of the accident any individual has died or will die, an individual other than the alleged offender has suffered serious bodily injury, or an individual other than the alleged offender has suffered bodily injury and been transported to a hospital or other medical facility for medical treatment;
  • The officer arrests the alleged offender for DWI with a child passenger;
  • At the time of the arrest, the officer possesses or receives reliable information from a credible source that the alleged offender has been previously convicted of or placed on community supervision for DWI with a child passenger, intoxication assault, intoxication manslaughter, or an offense under the laws of another state containing elements substantially similar to the elements of an offense under those sections; or
  • At the time of the arrest, the officer possesses or receives reliable information from a credible source that the alleged offender on two or more occasions, has been previously convicted of or placed on community supervision for DWI, flying while intoxicated, boating while intoxicated, assembling or operating an amusement ride while intoxicated, or an offense under the laws of another state containing elements substantially similar to the elements of an offense under those sections.

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Common Errors with Texas DWI Blood Tests

When a person is charged with DWI as the result of a blood test, it is important to immediately have a criminal defense lawyer review the handling of the blood sample in order to determine whether the test was lawfully ordered and properly handled. An attorney can file a motion to suppress evidence that was illegally obtained or challenge the accuracy of the results if there was any kind of mishandling of the blood sample.

A few of the most common kinds of problems that tend to arise with blood samples in DWI cases include, but are not limited to:

  • BAC affected by medication alleged offender was taking;
  • Blood not drawn by authorized medical personnel;
  • Blood test not authorized under law;
  • Contaminated sample;
  • Failure to convert serum or plasma alcohol concentration to whole blood alcohol concentration;
  • False positive;
  • Faulty or expired testing kit; or
  • Improper storage of sample.

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Dallas County Resources for DWI Blood Test Issues

Missouri v. McNeely, 133 S. Ct. 1552 — Tyler McNeely was stopped by a Missouri police officer stopped for speeding and repeatedly crossing the centerline. McNeely performed poorly on a number of field sobriety tests before declining to submit to a breath test. The officer transported McNeely to a station house where he again refused to provide a breath specimen, leading to the officer then taking McNeely to a local hospital for blood testing. After McNeely refused to submit to that test as well, the officer directed a lab technician to take a blood sample that ultimately showed McNeely had a BAC of 0.154 percent. The trial court, state appeals court, Missouri Supreme Court, and United States Supreme Court all agreed that the involuntary blood draw violated the McNeely’s Fourth Amendment rights of alleged offenders, although the United States Supreme Court left open the possibility that an exigent circumstances exception “applies when there is a compelling need to prevent the imminent destruction of important evidence, and there is no time to obtain a warrant.”

State v. Villarreal, 475 SW 3d 784 — David Villarreal was stopped in 2012 for a traffic violation when the police officer noticed signs of possible intoxication. Villarreal refused to submit to any field sobriety tests or provide a specimen for chemical tests, but police had a qualified technician draw Villarreal's blood under Texas Transportation Code § 724.012(b)(3)(B) because a criminal-history check revealed that Villarreal had been convicted of DWI on several occasions. The test revealed Villarreal had a BAC of 0.16 grams of alcohol per hundred milliliters of blood. Villarreal's attorney argued that the United States Supreme Court's decision in Missouri v. McNeely held that “in the absence of exigent circumstances, a DWI suspect's blood may not be drawn without a warrant, and he further argued that the federal Constitution overrides the Texas statute that authorizes a mandatory blood draw in certain situations.” On November 26, 2014, the Texas Court of Criminal Appeals affirmed the trial court’s decision to suppress the blood test results, concluding “that the warrantless, nonconsensual testing of a DWI suspect's blood does not categorically fall within any recognized exception to the Fourth Amendment's warrant requirement, nor can it be justified under a general Fourth Amendment balancing test.”


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The Law Offices of Richard C. McConathy | Dallas DWI Blood Test Lawyer

Was a blood test used to arrest you for an alleged DWI offense in North Texas? You will want to make sure that you retain legal counsel as soon as possible for help understanding all of your rights and achieving the most favorable possible outcome to your case.

The Dallas criminal defense attorneys of The Law Offices of Richard C. McConathy represent clients all over Dallas County, Denton County, Tarrant County, and Collin County. Call (972) 233-5700 or complete an online contact form right now to take advantage of a free consultation that will let our lawyers review your case and discuss your legal options.


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People ask every day how I'm not in prison, and my answer is to recommend this firm. Thank you again Richard, Brian, Amanda, Christina and Cynthia. God Bless. Nicholas D.
Tarrant County DWI
I can’t say enough great things about the attorneys at this law firm. Within a few months they had my case, which I thought I was going to lose, dismissed and put my life back on track. I would recommend their firm to anyone and everyone who is in need of legal help. Leslie L.
Denton County DWI
As a free man, I would highly recommend this law firm to anyone who is in serious trouble. They will do anything they can to save their clients. In my opinion they are the two best DWI lawyers in the state. Jeffrey F.
Dallas County DWI Intoxication Assault
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Denton County DWI
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