What Are Field Sobriety Tests in Texas?

If you’ve ever been pulled over and asked to “step out of the vehicle,” you know that moment can make your heart race. In Texas, this often leads to a field sobriety test — a set of physical and mental tasks police officers use to check if a driver might be intoxicated. But what exactly are these tests? Are they reliable? And do you really have to take them?

Whether you’re trying to make sense of what happened during your traffic stop or just want to understand your rights before anything happens, this article walks you through what field sobriety tests are, how they’re used in Texas, and what they mean for you legally.

Field Sobriety Test Simplified

Most DWI investigations in Texas start with something simple — speeding, swerving, or a busted taillight. Once an officer pulls you over, they’re looking for any signs of impairment: the smell of alcohol, slurred speech, bloodshot eyes, or slow movements.

If the law enforcement officer thinks you might be under the influence, the stop usually escalates to the next stage: the request to step out to perform a field sobriety test.

A field sobriety test (FST) is a set of physical and cognitive tasks that police use during a traffic stop to assess whether a driver might be intoxicated. These tests are designed to check for signs of impairment, like poor balance, lack of coordination, and slow reaction times.

The key word here is designed. These tests are not foolproof or scientifically perfect. They’re tools that officers use in the field to help decide whether to make a DWI arrest.

Standardized vs. Non-Standardized Field Sobriety Tests

In Texas—and across the U.S.—there are three standardized field sobriety tests recognized by the National Highway Traffic Safety Administration (NHTSA):

1. Horizontal Gaze Nystagmus (HGN) Test: The officer moves a pen or small object side to side in front of your eyes and watches how smoothly your eyes follow it.
2. Walk-and-Turn (WAT) Test: You’re asked to take nine heel-to-toe steps in a straight line, turn, and return the same way.
3. One-Leg Stand (OLS) Test: You’re asked to stand on one leg and count aloud until told to stop.

These three tests are part of what’s called the Standardized Field Sobriety Test (SFST) battery. They’re meant to be administered in a specific way, under specific conditions, and scored using specific criteria.

Officers might also use non-standardized tests like reciting the alphabet or touching your nose. These are not scientifically validated, but some departments still use them.

Is It Required to Take a Field Sobriety Test in Texas?

Here’s a crucial piece of information: you are NOT legally required to take field sobriety tests in Texas.

You can politely refuse. Field sobriety tests are voluntary, and refusing to take them is not a crime. However, refusing may still raise suspicion, and the officer may choose to arrest you and request a chemical test (like a breath or blood test).

But—and this is a big “but”—if you do agree to the test, your performance can be used as evidence against you in court.

How Accurate Are Field Sobriety Tests?

According to the NHTSA, the three standardized tests have the following accuracy rates when used individually:

• HGN: 77% accuracy
• Walk-and-Turn: 68% accuracy
• One-Leg Stand: 65% accuracy

When used together, the NHTSA claims the SFST battery can detect intoxication about 91% of the time. But that’s under ideal conditions—not in the dark, on a sloped road, in bad weather, or with someone who has a medical condition.

Things that can skew the results:

• Fatigue
• Anxiety
• Medical issues (vertigo, leg injuries, eye movement)
• Poor lighting or uneven pavement
• Age and weight

Can You Challenge the Results in Court?

Experienced DWI criminal defense attorneys in Texas often challenge the administration and reliability of field sobriety tests.

Common challenges include:

• The officer didn’t follow proper instructions.
• The test was given under poor conditions.
• Your physical or medical condition affected your performance.
• Video footage contradicts the officer’s report.

This is why it’s essential to speak with a lawyer immediately after a DWI arrest. They can analyze the body cam footage, test procedures, and cross-examine the officer if your case goes to trial.

Arrested? Don’t Plea, Call Me!

Field sobriety tests may look simple on the surface, but in reality, they carry serious legal weight—and they’re far from perfect. In Texas, just a few missteps or misunderstood signs can be used as evidence in a DWI case, even if you’re completely sober. Understanding your rights, how these tests work, and how to respond in the moment can make a world of difference.

If you’ve been arrested after a field sobriety test or believe your rights were violated during a DWI stop, Texas Criminal Defense Group is here to fight for you. Our experienced DWI attorneys know how to challenge flawed roadside tests and build a strong defense based on facts—not assumptions.