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Attacking DWI Test Results

When people are arrested for driving while intoxicated (DWI, but also commonly referred to as driving under the influence or DUI) in Texas as the result of any kind of failed tests, they typically assume that the test results essentially seal their guilt. The truth, however, is that any one of a number of possible errors in the administration of DWI-related tests can make the results invalid and prohibit a prosecutor from using them as evidence in drunk driving cases.

Police officers will typically employ multiple tests in order to prove that an alleged offender was legally intoxicated. People can face penalties for failure to submit to certain kinds of tests, but they may have perfectly valid reasons for why they allegedly failed some of these tests.

Lawyer for Attacking DWI Test Results in Fort Worth, TX

Were you arrested for an alleged DWI offense in the DFW area after supposedly failing certain sobriety tests? Do not assume that you will have to enter a guilty plea in court. Contact Townsend, Gebhardt & Eppes, PLLC as soon as possible.

Andrea Townsend, Steven Gebhardt, and Brian Eppes are experienced criminal defense attorneys in Fort Worth who aggressively defend clients facing DWI charges in communities throughout Tarrant County, Parker County, and Johnson County, including Fort Worth, Cleburne, Arlington, Weatherford, and many others. You can have our lawyers provide an honest and thorough evaluation of your case as soon as you call 817-502-3600 to schedule a free, confidential consultation.


Overview of DWI Testing Flaws in Tarrant County


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Attacking DWI Field Sobriety Test Results in Texas

Field sobriety tests are a variety of tests performed by alleged offenders that police officers frequently use before requesting the taking of a breath or blood specimen. Unlike breath or blood tests, Texas’ implied consent law does not require drivers to submit to field sobriety tests.

The legal validity of field sobriety tests has long been in question, and the National Highway Traffic Safety Administration (NHTSA) has only sanctioned three specific types of field sobriety tests:

  • Horizontal Gaze Nystagmus (HGN) — More commonly known as the “eye test,” nystagmus is the medical term for the involuntary jerking of the eye. If an alleged offender is under the influence of alcohol or a controlled substance, the jerking effect becomes more pronounced. When an officer administers an HGN test, he or she observes how well a person’s eyes follow a small object moving slowly from side to side about a foot from the subject’s face. When a subject’s eyes do not smoothly follow the object, it is often construed as probable cause for a DWI arrest.
  • Walk-and-Turn (WAT) — Officers instruct alleged offenders to take nine heel-to-toe steps along a straight line, turn on one foot, and return in nine heel-to-toe steps in the opposite direction. Any one of a number of mistakes can be used as probable cause for a DWI arrest.
  • One-Leg Stand (OLS) — Officers instruct alleged offenders to stand with one foot roughly six inches off the ground and count aloud by thousands for about 30 seconds. If an alleged offender has any kind of issue maintaining balance or counting, it is used as probable cause for a DWI arrest.

If a police officer uses any other non-sanctioned kind of field sobriety test (such as the Romberg Balance Test, the Finger-to-Nose Test, or any request to recite any portion of the alphabet in any order), courts may declare the test results invalid. Even if the alleged offender fails one or more of the standardized field sobriety tests, any one of a number of other issues can be cited as reason for the results.

A few of the most common reasons people fail NHTSA-standardized field sobriety tests include, but are not limited to:

  • Medical conditions;
  • Poor weather;
  • Disabilities;
  • Driver fatigue;
  • Improperly administered tests; or
  • Inaccurate police description of actual performance.

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Attacking DWI Breath Test Results in Tarrant County

Texas Transportation Code § 724.011 states that any person arrested for an offense arising out of acts alleged to have been committed while the person was operating a motor vehicle while intoxicated is deemed to have consented “to submit to the taking of one or more specimens of the person's breath or blood for analysis to determine the alcohol concentration or the presence in the person's body of a controlled substance, drug, dangerous drug, or other substance.” In essence, every motorist agrees to submit to breath testing simply by receiving a driver’s license in Texas, and refusal to submit to a breath test can lead to an automatic suspension of driving privileges—even if that person is not convicted of DWI.

Breath tests are the most common way authorities measure the intoxication level of alleged offenders because the equipment is much easier to use and the results are instantaneous. Even when an alleged offender submits to a test and the results show an alcohol concentration of 0.08 or higher, certain errors can lead to the test results being declared inadmissible.

A few common issues with breath tests (commonly referred to as breathalyzers) include, but are not limited to:

  • Breathalyzer not properly calibrated;
  • Breath test operator not certified;
  • Tests conducted without observation period;
  • Mouth alcohol from other sources produced false positive; or
  • Results contaminated by interference from electronic devices.

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Attacking DWI Blood Test Results in Fort Worth

In certain cases when alleged offenders either are physically unable or otherwise refuse to provide breath samples, authorities may ask—or possible even force—alleged offenders to submit to blood testing. Blood tests are viewed as the most accurate way of testing a person’s blood alcohol concentration (BAC), but they are also the most invasive.

The taking of a blood specimen also has much stricter requirements under state law. Texas Transportation Code § 724.017 establishes that the only people authorized to take a blood specimen at the request or order of a peace officer are:

  • A physician;
  • A qualified technician;
  • A registered professional nurse;
  • A licensed vocational nurse; or
  • A licensed or certified emergency medical technician-intermediate or emergency medical technician-paramedic authorized to take a blood specimen under Texas Transportation Code § 724.017(c).

The most common issues relating to blood test results in DWI cases revolve around how the samples were handled. Some of the reasons a blood sample might be inadmissible in a DWI case include, but are not limited to:

  • Failure to use tamper-proof seals
  • Contaminated sample;
  • Failure to sterilize medical equipment;
  • Illegally obtained sample;
  • Improper storage of sample;
  • Test performed by unauthorized individual;
  • Decomposition of sample produced false positive; or
  • Whole blood value was actually plasma or serum.

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Texas Resources for Attacking DWI Test Results

Chapter 724 | Texas Transportation Code — View the full text of state laws in Texas relating to implied consent. Find information about consent to the taking of a specimen, prohibitions on the taking of a specimen, and information that must be provided by officers before requesting specimens. Learn more about the different requirements relating to breath and blood specimens as well as an individual’s rights concerning additional analysis.

Texas Breath Alcohol Testing Program Operator Manual — View the manual that serves as a textbook for breath alcohol testing operator initial certification training. The manual’s chapters cover laboratories, instrumentation, and evidential breath analyses. One chapter is also dedicated to the metric system and the manual contains various ilustrations.


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Townsend, Gebhardt & Eppes, PLLC | Fort Worth DWI Test Defense Attorney

If you were arrested in the greater DFW area for an alleged drunk driving crime after failing any kind of sobriety test, it is in your best interest to immediately retain legal counsel. Townsend, Gebhardt & Eppes, PLLC can investigate how these tests were administered and fight to possibly get the criminal charges reduced or dismissed.

Fort Worth criminal defense lawyers Andrea Townsend, Steven Gebhardt, and Brian Eppes represent clients in Weatherford, Fort Worth, Cleburne, Arlington, and several surrounding areas of Tarrant County, Parker County, and Johnson County. Call 817-502-3600 or complete an online form to let our lawyers review your case and answer all of your legal questions during a free initial consultation.


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