What could cause poor performance of a field sobriety test during a Texas DWI stop?

Have you recently been arrested for DWI and perform poorly on roadside sobriety tests? Alcohol may not be to blame. There are many factors that can impact test results. If you want to beat DWI charges in Houston it's important to hire an attorney who knows how to attack field sobriety test results.

At the Doug Murphy Law Firm, our Houston DWI defense attorneys are dedicated to protecting your future. We will thoroughly investigate your arrest and determine all of the factors that could have caused you to perform poorly on sobriety tests. Using this information, we'll attack the state's evidence against you. This will help you secure the best possible result in your Houston DWI case.

Field Sobriety "Tests" Aren't Reliable - Sober People Fail them Too

Field sobriety tests are supposed to help police officers determine if you are intoxicated. Police rely on these tests to gather proof to make an arrest for DWI. They're often used when you smell like alcohol, admit drinking alcohol, have red bloodshot eyes, slurred speech or show others clues of intoxication that police officers are trained o recognize as a sign of impairment. Remember, all that is need to be arrested for DWI in Texas is the police to have a "reasonable suspicion" that you are intoxicated. A reasonable suspicion is, more often than not, nothing more than the odor of alcohol and visual cues of your eyes and speech. Add on any clues from the field sobriety exercises, and even a sober person will be arrested for DWI.

The problem with field sobriety tests, however, is that they're not a particularly good indicator of intoxication. In fact, the National Highway Traffic Safety Administration found that field sobriety tests are only 66-75 percent accurate--at best. And that's only when tests are administered properly. Police typically make mistakes when administering sobriety tests that can invalidate the results.

Factors That Can Cause Poor Performance on Field Sobriety Tests


It is a frightening experience to be pulled over by a police officer during the day. But when a person is pulled over at night by a police officer and they only drank a small amount of alcohol, it will certainly cause nervousness to rise even higher. Most people do not respond well to stress and the nervousness can create the clues officers are looking for to make an arrest decision. Further, the nervousness blocks a person's ability to listen to all the drill sergeant-like instructions given prior to performing field sobriety test. These tests resemble a game of "Simon says, Simon does" that result in an arrest if a person doesn't follow police orders.

Poor Instructions

You can't do well on a test if you aren't given good instructions. Unfortunately, this is a common reason that drivers perform poorly on field sobriety tests. Police officers tend to have a difficult time explaining a complex set of rules in a short period of time in a way that's easy to understand. It's easy to perform poorly on a test or seem as if you are intoxicated if you're confused about what you're supposed to do to complete the test successfully.

Poor Coordination

A major problem with field sobriety tests is that officers don't know you. This means that they don't know how you would have performed on the tests if you were (a) sober and (b) not under immense pressure. Without this knowledge, police officers can't really set a benchmark for “success.” What if you are just an uncoordinated individual? What if you are prone to tripping or walking at an angle? These factors can definitely cause you to perform poorly on field sobriety tests.

Medical Conditions

Police should ask you if you have any medical conditions that may affect your ability to perform field sobriety tests. However, they may not believe you or take those conditions into account. Medical conditions that could affect your field sobriety test performance could include:

  • Arthritis
  • Knee problems
  • Foot injury
  • Brain injury
  • Speech impediments
  • Hearing difficulty
  • Poor circulation
  • Back problems
  • Ear and balance issues, or
  • Recent surgery.

In theory, any medical condition could affect your field sobriety test performance. An experienced DWI attorney will use this information to undermine the validity of your test results.


Symptoms of fatigue can look a lot like intoxication. Fatigue can also cause you to perform poorly on roadside sobriety tests. When police ask you to walk in a straight line or balance on one foot, the fact that you're tired will definitely be a factor. Make sure that you identify why you are fatigued to help explain why the field sobriety test results are not an accurate indicator of intoxication.


Did you consume caffeine before hitting the road? Caffeine is a stimulant that can cause you to have a lot of nervous energy. Caffeine can elevate your heart rate, send adrenaline rushing through your system, and affect your nervous system. These can all be a detriment when you are trying to complete tests with accuracy.

Road Surface

Field sobriety tests are most accurate when they are administered according to departmental guidelines. This typically means that officers should find a flat, paved surface that can give you the best chance to complete the tests successfully. However, most officers just administer tests wherever the traffic stop occurred. As a result, you may be asked to perform on:

  • Gravel
  • Cracked or uneven surfaces
  • Mixed surfaces (e.g., gravel, concrete, and pavement)
  • Uneven surfaces, or
  • Slippery surfaces.

These conditions do not set you up for success. Poor performance could definitely be connected to the officer's poor administration of the test.


Were you wearing high heels or sandals when you were asked to complete field sobriety tests? Or maybe you had on boots with a broken heel. The shoes you wear will definitely play a role in your performance. Your best performance will happen when you are wearing flat, tightly-laced shoes with good traction. Any other shoes can limit your ability to walk in a straight line and stand on one foot.


Age can definitely be a factor in field sobriety test performance. If you are older, you may have difficulty standing or walking for extended periods of time. You may also be more prone to suffering from physical conditions that limit your ability to pass these roadside tests.


Did the officer take your weight into account when giving your instructions for the field sobriety tests? Did they consider the fact that you are obese or overweight may affect your ability to perform well on those tests? Probably not. However, they should have. If you are overweight you will have a more difficult time walking a narrow line or demonstrating balance for an extended period of time. Obesity can also cause you to suffer from other health conditions (e.g., diabetes, vision problems) that could factor into your performance.


Traffic conditions can affect your field sobriety test performance. Why? Traffic can be a huge distraction. Distractions may include:

  • High-speed travel
  • Accidents
  • Traffic lights (and unwelcome spectators)
  • Pedestrians
  • Traffic sounds (e.g., horns, hard brakes), and
  • Lights.

If you find that it is difficult to focus on the sobriety test, you may not do particularly well.


The weather during your field sobriety tests can also play a part in your performance. You're less likely to do well if it is:

  • Raining
  • Snowing
  • Windy
  • Sleeting
  • Icy
  • Extremely cold or hot, or
  • Wet because of a recent storm.

It's important to make note of the weather conditions during your field sobriety tests. Your attorney can bring these issues to light when you are fighting your DWI.


Getting stopped for DWI can be a nerve-wracking experience. This is particularly true if you have been falsely accused of drinking and driving. Your nerves can be your worst enemy while you are completing sobriety tests. You'll be more likely to have a misstep, fall, or lose your balance. Officers will think that these are all signs of intoxication. However, in reality, it's simply your nerves getting the best of you.

Attacking the Validity of Field Sobriety Test Results

Did any of these factors contribute to your poor performance on field sobriety tests? If so, it's important to speak with an experienced DWI defense attorney immediately. Your attorney will know how to use this information to attack the state's case against you.

The state has to prove that you are guilty of DWI beyond a reasonable doubt. If you did not fail chemical tests (e.g., breath or blood test), the police will try to say that other evidence shows that you were intoxicated. The results of field sobriety tests are usually at the forefront. Attacking the validity of those results and giving valid reasons for your poor performance is the best strategy for your defense. Without evidence to support its case, the state will be forced to offer a plea or drop the charges against you.

Houston DWI Lawyer

If you want to win your case you'll need the best Houston DWI defense attorney by your side. Doug Murphy is one of four lawyers in Texas who is Board Certified in DWI Defense. Doug has been handling the most complex DWI matters in Texas for more than 19 years and has taught others lawyers how to successfully challenge field sobriety exercises all over the United States. He understands that field sobriety tests can be influenced by a number of external factors. By requesting and reviewing a recording of your test, Doug Murphy will identify the issues that may have contributed to poor performance. He'll pair these issues with the information you've provided and devise a winning defense strategy.

Are you interested in fighting DWI charges in Houston? Call the Doug Murphy Law Firm, P.C. to schedule a free case evaluation. We are here to help you fight to protect your future.

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If you are facing DWI or other criminal charges in Texas, contact our office today to discuss your case, so we can begin working on your defense. Please provide only your personal email and cell phone number so that we can immediately and confidentially communicate with you.