The question: Do I have to take a field sobriety test in Texas?

The short answer: No. Field sobriety tests are voluntary in Texas. You are not required to perform them, you cannot be charged with a separate offense for refusing, and there is no automatic license suspension for declining (unlike the breath or blood test which carries its own consequences for refusal). Officers will not always tell you these tests are voluntary. You can decline politely and consistently. The tests themselves are far less reliable than they are presented to be, and refusing them removes a meaningful piece of evidence the State will otherwise use to argue you were intoxicated.

Here is the longer answer: what field sobriety tests actually are, why they are voluntary, why their reliability is overstated, and what happens if you decline.

What Field Sobriety Tests Are

“Field sobriety tests” means the three Standardized Field Sobriety Tests (SFSTs) developed by the National Highway Traffic Safety Administration (NHTSA) in the 1970s and 1980s and still used today. The three tests are:

  • Horizontal Gaze Nystagmus (HGN). The officer asks you to follow a stimulus (a pen or finger) with your eyes only and watches for involuntary jerking of the eye.
  • Walk-and-Turn (WAT). The officer asks you to take nine heel-to-toe steps along a real or imaginary line, turn in a specific way, and take nine more steps back, while counting aloud and following specific instructions.
  • One-Leg Stand (OLS). The officer asks you to stand on one leg with the other leg held six inches off the ground, count out loud, and hold the position for thirty seconds.

Officers may also ask you to perform non-standardized tests such as reciting the alphabet, counting backwards, the finger-to-nose test or the Romberg balance test. None of these are validated by NHTSA, and all of them are voluntary.

Why They Are Voluntary

Texas law does not require a driver to perform field sobriety tests. There is no statute analogous to the implied consent law that governs breath and blood testing. There is no separate offense for refusing. There is no automatic license suspension. The tests are presented to you in a way that suggests refusal is a problem (“I just need you to do a few things for me”) but you have the legal right to say no.

This is one of the most important pieces of information in DWI defense, and one of the most consistently underexplained to the public. Officers are not required to tell you the tests are voluntary, and most do not. The presumption built into the encounter is that you will perform them. The legal reality is that you do not have to.

Why the Tests Are Less Reliable Than They Look

Field sobriety tests are presented as objective scientific assessments. They are not. They are observational tests scored by the officer based on the officer’s perception of “clues”. Clues are specific behaviors NHTSA has linked, with varying degrees of validation, to alcohol impairment. Each test has well-documented limitations:

  • HGN problems. Nystagmus has many causes other than alcohol such as fatigue, certain medications, neurological conditions, head injuries, exposure to certain chemicals, even high caffeine intake. The administration of the test (stimulus distance, angle, speed of movement, head positioning) has to follow precise protocols, and deviations are common. Body camera and dashcam review frequently shows administration that does not meet the NHTSA standard.
  • Walk-and-Turn problems. The test is designed to be administered on a flat, dry, hard, non-slippery surface. The reality of a roadside stop (sloped shoulder, gravel, mud, weather, traffic noise) is rarely that. Footwear, fatigue, age, weight, back and knee problems, vestibular conditions, and inner ear issues all affect performance. NHTSA itself has noted that subjects over 65 or with certain physical conditions may have difficulty with the test even when sober.
  • One-Leg Stand problems. Similar issues. Balance is affected by the same factors as walk-and-turn such as surface conditions, footwear, fatigue, age, weight, physical condition, and a host of medical issues. Anyone who has tried to balance on one foot in a stressful environment knows that thirty seconds is longer than it sounds.
  • Roadside conditions. Flashing emergency lights, traffic noise, weather, time of night, and the sheer stress of being investigated for DWI all affect performance. None of these are accounted for in the original NHTSA validation studies, which were conducted under controlled conditions that bear little resemblance to a real Texas DWI stop.

None of this means SFSTs are useless. It means they are observational evidence subject to interpretation, not chemical evidence with a defined error rate. The State will present a defendant’s SFST performance as objective proof of intoxication. A forensic-trained defense lawyer will present the same performance as an unreliable observational test administered under poor conditions to a person whose innocent factors were never accounted for.

What Happens If You Refuse

If you decline to perform field sobriety tests at the roadside, here is what does and does not happen:

  • You are not charged with refusing. There is no separate offense for declining SFSTs in Texas.
  • Your license is not automatically suspended. The Administrative License Revocation process is triggered by refusal of a breath or blood test but not by refusal of field sobriety tests.
  • The officer may still arrest you. If the officer believes there is probable cause for DWI based on driving behavior, observations, statements, and other indicators, the officer can arrest you without SFSTs.
  • Your refusal can be mentioned at trial. Some Texas courts allow the State to introduce evidence that the defendant declined SFSTs, and to argue that refusal suggests consciousness of guilt. The defense response is straightforward: the tests are voluntary, the defendant exercised a legal right, and a refusal of an unreliable observational test does not equal an admission of intoxication.

The trade-off is real but generally favorable to the defendant: by declining, you remove a category of evidence the State would otherwise use, in exchange for the possibility that the prosecution will mention your refusal. In most cases, that is a trade worth making because once you perform the tests, the officer’s scoring of your performance, on video, becomes part of the State’s case against you.

How to Decline

Politely and consistently. The same script that works for declining other roadside requests works here:

  • “Officer, I respectfully decline to perform any tests.”
  • “I’d prefer not to do that without a lawyer.”
  • “I understand you’re asking, but I’d rather not.”

Do not argue. Do not lecture the officer about the validity of NHTSA studies. Do not explain why you would have failed even sober. Decline once, decline again if asked again, and stop talking. The video should show a calm, polite person exercising their rights and not a person trying to talk their way out of a stop.

What About the Portable Breath Test (PBT)?

After or during the SFSTs, officers often ask the driver to blow into a small handheld device on the side of the road. This is the portable breath test, or PBT. It is a screening device, not the evidentiary instrument used at the station. The roadside PBT is voluntary in Texas, and you can decline it the same way you decline SFSTs.

Declining the PBT is a separate decision from declining the breath or blood test at the station. The DIC-24 statutory warning, the implied-consent framework, and the ALR consequences all apply to the station test but not the roadside PBT.

If You Have Already Performed Field Sobriety Tests

If you took the tests before reading this post or talking to a lawyer, you are not without recourse. SFST evidence is one of the most challengeable categories of evidence in a DWI case. Defense counsel can:

  • Review the video. Body cam and dashcam footage usually tells a different story than the officer’s narrative report. Administration errors, scoring inconsistencies, and conditions that confound the test are routinely visible.
  • Examine the officer’s training and certification records. SFST certification has expiration dates, refresher requirements, and documented standards. Lapses and gaps are common.
  • Develop the medical and physical issues that affected performance. Age, weight, back and knee problems, vestibular issues, neurological conditions or eye conditions can all can be developed through medical records and expert testimony.
  • Cross-examine on the conditions of administration. Surface, lighting, weather, traffic, footwear, and the officer’s adherence to NHTSA protocol are all fair game.

Performing the tests is not the end of the case. It just means the defense work has to be more thorough.

The Bottom Line

Field sobriety tests are voluntary in Texas. They are observational, subjective, and far less reliable than the State will lead a jury to believe. Declining them removes a category of evidence the prosecution will otherwise use, while exposing the defendant to only a manageable trial argument about why the refusal occurred. If you can remember anything before a DWI stop ever happens, remember this: identify yourself, hand over your license, decline the tests, request a lawyer, and stop talking. The roadside is the wrong place to try to win a DWI case. The right place is a courtroom with a defense lawyer who knows the science.

For a more detailed history of the development of the SFST’s please read our guide to the history and science of field sobriety tests.

DWI Defense at Deandra Grant Law

Deandra Grant Law defends DWI and intoxication-offense cases across North and Central Texas including Dallas, Fort Worth, Plano, McKinney, Frisco, Allen, Lewisville, Denton, Rockwall, and Waco. We review SFST administration on every traffic stop video, identify the protocol failures and confounding factors that the offense report leaves out, and challenge the evidence at the level the science requires. Deandra Grant herself is an SFST instructor.

If you have been arrested for DWI in Texas (whether you took the field sobriety tests or declined them) call Deandra Grant Law at (214) 225-7117 to schedule a confidential consultation. And remember that the 15-day ALR deadline runs from the date of service of the notice of suspension.

Have a DWI question you want answered in this series? Submit it at texasdwisite.com — you might see it featured in a future Ask Deandra post.