Field Sobriety Tests in Houston DWI Cases: What They Really Measure and Why They Matter

Are Field Sobriety Tests Required After a DWI Stop in Houston?

After a DWI stop in Houston, many drivers find themselves standing on the side of the road being asked to perform field sobriety tests. These roadside exercises often feel mandatory — but that perception isn’t always accurate.

As a Houston DWI defense attorney, I regularly review cases where field sobriety tests play a major role in the arrest decision. Understanding what these tests actually measure — and their limitations — is critical to understanding how DWI cases are built in Texas.

Are field sobriety tests there to judge your level of intoxication or are they designed for you to fail?

What Are Field Sobriety Tests?

Field sobriety tests are physical and cognitive exercises used by law enforcement to assess signs of impairment. In Texas, officers typically rely on three standardized tests:

• Horizontal Gaze Nystagmus (HGN)

• Walk-and-Turn Test

• One-Leg Stand Test

These tests are designed to help officers decide whether they believe probable cause exists for a DWI arrest — but they are not scientific proof of intoxication.

Are You Required to Perform Field Sobriety Tests in Texas?

This is one of the most misunderstood aspects of DWI law.

In Texas:

• Field sobriety tests are voluntary

• You are not legally required to perform them

• Refusing field sobriety tests does not automatically mean guilt

However, refusal may influence the officer’s decision-making, which is why the situation requires careful judgment.

Why Field Sobriety Tests Are Often Unreliable

Field sobriety tests are conducted:

• On uneven surfaces

• In poor lighting

• Under stress

• Often late at night

• Sometimes in bad weather

Additionally, many factors unrelated to alcohol can affect performance, including:

• Fatigue

• Anxiety

• Medical conditions

• Injuries

• Age

• Footwear

These variables make field sobriety tests far less reliable than many people assume.

The Role of Field Sobriety Tests in Houston DWI Arrests

In Houston and Harris County, field sobriety tests are frequently used to justify:

• The DWI arrest itself

• Requests for breath or blood testing

• License suspension proceedings

They often appear prominently in police reports and officer testimony. However, these tests are subjective, meaning they depend heavily on the officer’s interpretation.

This is why field sobriety tests often become a focal point in both the ALR hearing and the criminal DWI case.

How Field Sobriety Tests Affect License Suspension (ALR Hearings)

Field sobriety test observations are often used to support license suspension claims during the ALR process.

Understanding how these tests are interpreted is an important part of protecting driving privileges. This issue is discussed further in our Houston DWI ALR hearing guide, which explains how early hearings can impact both license suspension and the broader defense strategy.

Can Field Sobriety Tests Be Challenged in Court?

Yes — and they often are.

Common challenges include:

• Improper administration of the tests

• Failure to follow standardized protocols

• Inaccurate instructions

• Officer bias or assumptions

• Video evidence contradicting written reports

Video footage from dash cameras or body cameras frequently tells a different story than what appears in police reports.

Field Sobriety Tests vs. Chemical Testing

It’s important to distinguish between field sobriety tests and chemical tests.

• Field sobriety tests assess behavior and coordination

• Breath and blood tests attempt to measure BAC

Both can be challenged — and understanding the differences between blood and breath tests is especially important when chemical testing becomes part of the case.

What This Means for Drivers Arrested for DWI in Houston

Field sobriety tests often feel like a formality, but they can significantly influence what happens next — including arrest decisions, license suspension, and charging.

The key takeaway is this:

Field sobriety tests are tools, not proof — and they deserve careful legal scrutiny.

Understanding their limitations can change how a DWI case is defended.

Learn More About Houston DWI Defense Options

If you’ve been arrested for DWI in Houston or Harris County, knowing how field sobriety tests, chemical testing, and license suspension interact can help you make informed decisions early.

For a broader overview of the entire process, see our complete Houston DWI defense guide, which explains each stage of a DWI case and what to expect.