DWI Testing

Closeup of a man blowing into a breathalyzer DWI test

If you were pulled over for suspected drinking and driving in Dallas, TX, the officer will probably ask you to take a set of field sobriety tests. You may also be asked to blow on a breathalyzer machine to measure your breath-alcohol concentration. You have the option to refuse alcohol testing in Texas.

There are consequences for refusing, though. Your driver’s license will automatically be suspended. If you are convicted of DWI in court, other court imposed penalties can result after a conviction for any driving while intoxicated (DWI or DUI) offense.

In Texas, many communities have implemented “No Refusal Weekends.” If an individual is suspected of driving while intoxicated by alcohol or drugs, they will be asked to submit to a blood- or breath-alcohol concentration (BAC) test. If they refuse, the officer can quickly get a judge to sign a warrant to take your blood by force.

This website is intended to provide you with general information about the testing process for DWI cases in Texas. In this article, we will briefly cover a number of DWI-related topics. For more detailed information, we provide dedicated pages for each of the following topics:

Consulting with an experienced attorney can provide you with deeper insight into your situation after a detailed analysis of your case.

Lawyer for DWI Testing in Dallas, TX

Contact the Law Offices of Richard C. McConathy if you have been charged with a DWI offense in Dallas. Their attorneys have represented clients across North Texas, including Garland, Irving, Grand Prairie, Irving, and Mesquite.

Attorney Richard McConathy is an experienced DWI lawyer. He will scrutinize the evidence in your case for defenses or mitigating factors. Whenever possible, he will fight to have your DWI charge reduced or dismissed.

Contact the Law Offices of Richard C. McConathy for a free consultation if your DUI arrest involved the use of chemical or field testing.


Dallas DWI Testing Information Center


Back to top

Texas Transportation Code Section 724.011 defines the concept of implied consent. Implied consent means every individual who drives on Texas roads automatically consents to breath or blood testing when pulled over for suspicion of DWI.


Back to top

Texas DWI Field Sobriety Tests

Texas law enforcement officers typically first use a field sobriety test to detect impairment if they have pulled an individual over for DWI. The standard field sobriety tests (FSTs) law enforcement officers may use include those described below.

A police officer may have you walk a number of steps in a straight line, turn, and repeat. The test requires you to walk heel-to-toe for the number of steps the officer tells you to take, then the same amount of steps back. The officer is typically looking for a lack of balance, stumbling or falling, using arms for balance, and the ability to follow instructions.

The officer may have you stand on one leg and count numbers out loud. The officer is testing your ability to do two tasks involving normal mental and physical abilities. During this test, the officer will determine if you are capable of performing the task without stumbling, losing balance, hopping, putting your foot down, moving your arms, or incorrectly reciting the numbers.

The officer may move a pen or small light back and forth in front of your eyes while your head is still. This test, also called the horizontal gaze nystagmus (HGN) test, is used to determine whether an individual’s eyes are able to follow an object without nystagmus, or involuntary jerking of the eyes. A failure of this test usually indicates a very high BAC. However, many people suffer from nystagmus without the consumption of alcohol.

The officer may also have you stand with your feet apart while you tilt your head backward to test balance. You could also be asked to fully or partially recite the alphabet in reverse.

These tests do not conclusively show whether an individual is intoxicated. The results of a field sobriety test are ultimately a matter of the officer’s opinion. It’s possible to “fail” a field sobriety test for a variety of reasons. Some people are uncoordinated or have nystagmus of the eyes regardless of their level of intoxication. The closest method to determining whether an individual has consumed alcohol is through a breath or blood chemical test, but even those are not completely accurate.


Back to top

DWI Breath Tests in Texas

An individual suspected of DWI may also be requested to submit to a breath test to determine their alcohol concentration level. If they consent and blow over the legal limits of 0.08, they will automatically be arrested for DWI under Texas’s per se DWI law. However, they can also be arrested if the law enforcement officer believes their normal mental and physical faculties are impaired from the use of alcohol or drugs.

According to Texas Transportation Code Section 724.016, an arrested DWI offender’s breath specimen is permitted to be taken by a peace officer and analyzed by a qualified individual.

If an individual takes a breath test and blows over the legal limit, the results of the test may be challenged in court. The results of the Intoxilyzer 5000, also known as a breath test machine or breathalyzer, can sometimes be inaccurate or unreliable. For example, failure to calibrate the machine could result in readings showing a spike in breath-alcohol concentration. The breathalyzer will also output an inaccurate reading if the person administering is not properly trained or does not follow proper procedure. If the suspect has toothpaste or mouthwash residue in their mouth, the machine is also likely to produce an inaccurate reading.


Back to top

Portable Breath Test vs. Post-Arrest Breath Test

The police use two different types of breath test during a DWI investigation. The first, a portable breath test, is administered during a traffic stop. The second is a post-arrest breath test performed on a DWI suspect after they’ve been arrested.

When a police officer pulls you over for suspicion of DWI, they are looking for a reason to arrest you and get you off the road. You may be asked to submit to a portable, pre-arrest breath test to provide a reading of your breath-alcohol content during the traffic stop. This test is also known as a preliminary alcohol screening (or PAS).

You are allowed to refuse the portable test, but there’s a catch. Your refusal will be used as probable cause to arrest you, and your license will be automatically placed on administrative suspension. We will briefly cover the administrative license suspension process in a separate section. You can also find more detail on our page about administrative license revocation.

If the officer decides he or she has probable cause to arrest you for DWI, you’ll be handcuffed and taken to jail. Most police stations will have a non-portable infrared breathalyzer you’ll be asked to submit to. If you refuse this test, you also face suspension of your license. The police may then request that a judge issue a warrant to allow them to take a sample of your blood as evidence. In that situation, you would have no choice but to submit.


Back to top

Dallas DWI Blood Testing

When an individual is arrested for DWI in Dallas, the arresting officer may take the alleged offender’s blood sample to test for alcohol concentration levels. Blood-alcohol concentration (BAC) is usually tested through a process called gas chromatography. This method compares the individual’s blood sample against a control sample.

According to Texas Transportation Code Section 724.017, only certain people may take a DWI suspect’s blood when requested by a peace officer.

Inaccuracies may also arise when an individual’s blood is tested for alcohol concentration levels. If an unauthorized person performs the blood draw, the results of the test may be thrown out in court. Also, samples taken in a hospital after the individual was involved in a car accident are taken from the blood serum and not the whole blood. This often results in a less accurate measurement.


Back to top

Administrative License Suspension in Dallas

If an individual refuses to submit to chemical testing in Dallas for a DWI, their license will automatically be revoked. This is not a criminal penalty for a DWI, but a civil penalty. If the individual is subsequently convicted of a DWI in Dallas, they may also have their license suspended as part of a criminal penalty.

After the individual receives notice of a suspension, they can submit a written request for a hearing. This must be done within 15 days of the notice of suspension. At the hearing, the Office of Administrative Hearings will determine if the license suspension was justified.

According to Texas Transportation Code Section 724.035, the period of suspension is 180 days for a first DWI refusal. Subsequent refusals will result in a two-year license suspension each time.


Back to top

Resources for Driving While Intoxicated (DWI) Testing in Texas

Texas Constitution and Statutes – This link is to chapter 724 of the Texas Transportation Code. Here you can read about implied consent and chemical DWI testing in Texas. You can also view the potential penalties for a testing refusal.

Texas Breath Alcohol Testing Program Requirements – This link is to the operator’s manual of the Texas Breath Alcohol Testing Program. The manual contains information about how breath tests in Texas must be administered. Here you can view information about alcohol concentration levels, invalid tests, ethanol information, and details about the Intoxilyzer 5000.

Texas Alcoholic Beverage Commission – The Texas Alcoholic Beverage Commission (TABC) is a state agency that regulates the alcoholic beverage industry throughout Texas. This link provides access to information about Texas’s DWI laws, signs of intoxication, and miscellaneous alcohol consumption information. A local field office is located at:

TABC
2225 East Randol Mill Road, Suite 200
Arlington, Texas 76011
Phone: (817) 652-5912


Back to top

Finding an Attorney for DUI Testing in Dallas-Fort Worth, TX

Portrait of Dallas criminal defense attorney Richard McConathyContact Law Offices of Richard C. McConathy today if you’ve recently failed a DWI sobriety test. Richard McConathy is a knowledgeable Dallas DWI attorney who has represented thousands of clients just like you. He will make every effort to help you achieve the best possible outcome for your alleged DWI offense.

Complete the online form to schedule a free consultation. The Law Offices of Richard C. McConathy represents North Texas clients in the counties of Johnson, Ellis, Rockwall, Dallas, Tarrant, and Collin.


Back to top

This article was last updated on Tuesday, January 29, 2019.

Client Testimonials

Read More Stories
(972) 233-5700
  1. videosVideos
  2. phone
  3. case resultsResults
  4. contactContact
X