Field Sobriety Tests in Texas: How We Challenge Them in Montgomery County

Field Sobriety Tests in Texas DWI Defense

Field sobriety tests are often a major part of a DWI arrest. The officer may ask a driver to follow a stimulus with their eyes, walk a straight line, or stand on one leg. The officer then writes down clues that are used to support an arrest.

These tests can look simple, but they are not simple in court. They are based on training protocols. They must be explained properly, demonstrated properly, and judged fairly. Weather, lighting, road surface, age, injuries, nerves, footwear, and medical conditions can all affect performance.

This article explains the three common standardized field sobriety tests, common protocol errors, and how Tim Rose reviews these tests in Montgomery County DWI cases.

For the full DWI overview, read the Complete Guide to DWI Defense in Montgomery County.

What Are Standardized Field Sobriety Tests?

The National Highway Traffic Safety Administration, often called NHTSA, provides training materials for DWI detection and standardized field sobriety testing. The three main standardized tests are:

• Horizontal Gaze Nystagmus, often called HGN
• Walk and Turn
• One Leg Stand

These tests are supposed to help officers look for signs of impairment. But the word standardized matters. If the officer changes the instructions, rushes the test, skips steps, grades unfairly, or ignores medical issues, the test may be less reliable.

The HGN Eye Test

The HGN test is the eye test. The officer asks the person to follow a stimulus, often a pen or finger, while keeping the head still. The officer looks for involuntary jerking of the eyes.

Defense issues may include:

• The officer moved the stimulus too fast
• The officer held the stimulus too high or too close
• The person moved their head because instructions were unclear
• The officer failed to check for equal tracking
• Flashing lights affected the test
• Medical conditions affected the eyes
• The officer recorded clues that are not visible on video

HGN can be powerful evidence when done correctly, but it is also easy for officers to overstate. Video review is important.

The Walk and Turn Test

The Walk and Turn test asks the person to stand heel-to-toe, listen to instructions, take nine heel-to-toe steps, turn in a specific way, and take nine steps back. It is a divided-attention test, meaning the person must listen, remember, balance, and move at the same time.

Common defense issues include:

• The surface was uneven, sloped, wet, or poorly lit
• The person was not given a real line
• The officer gave confusing instructions
• The officer did not properly demonstrate the turn
• The person had knee, back, ankle, hip, or balance problems
• The person wore boots, heels, sandals, or poor footwear
• Traffic or emergency lights created stress
• The officer counted a clue that was caused by the testing conditions

This test can punish people who are nervous, tired, injured, older, or simply confused by the instructions.

The One Leg Stand Test

The One Leg Stand test asks the person to raise one foot, keep both legs straight, keep arms at the side, look at the raised foot, and count until told to stop.

Common problems include:

• The officer did not explain the instructions clearly
• The officer stopped the test too early or ran it too long
• The person had medical or balance issues
• The ground was unsafe or uneven
• The person was wearing poor footwear
• The person used arms for balance because of nerves or conditions
• The officer failed to consider age, weight, or injury

A person can struggle with this test for reasons that have nothing to do with intoxication.

Common NHTSA Protocol Errors

Field sobriety testing is only useful when the officer follows the training. Common errors include:

• Giving incomplete instructions
• Failing to demonstrate the test correctly
• Starting the test before the person understands
• Testing on an unsafe or uneven surface
• Ignoring medical conditions
• Counting clues that do not match the video
• Using non-standard instructions
• Rushing through the test
• Failing to ask about injuries
• Failing to record important parts of the test
• Writing a report that sounds worse than the video looks

These mistakes may not automatically dismiss a DWI case, but they can weaken the State’s evidence.

Why Body Camera and Dash Camera Video Matter

The police report is only one version of events. Video may show something different. A report may say the driver was unsteady, but video may show steady movement. A report may say the person failed instructions, but video may show the officer gave unclear instructions.

Video can also show weather, traffic, officer tone, lighting, road conditions, shoes, fatigue, stress, and how the person actually looked and sounded.

For more on the arrest timeline, read What Happens After a DWI Arrest in Montgomery County, Texas.

Tim Rose’s Review Approach

At the Law Office of Timothy Rose, field sobriety tests should be reviewed step by step, not accepted at face value. A careful review looks at what the officer said, what the person did, what the video shows, and whether the test was fair.

The review should include:

• Comparing the police report with the video
• Checking whether the stop itself was lawful
• Reviewing the exact instructions given
• Looking for missed or exaggerated clues
• Checking road, weather, and lighting conditions
• Identifying injuries or medical issues
• Comparing field tests with breath or blood results
• Looking for signs the officer decided too early to arrest

This approach helps separate real evidence from assumptions.

How Field Tests Connect to Breath and Blood Evidence

Field sobriety tests should be compared with chemical testing. If field tests look strong but the breath or blood result is low, that can raise questions. If the alcohol number is high but the field tests look normal, that can also raise questions.

For more on testing evidence, read Breath Test vs. Blood Test in Texas DWI Cases.

Can You Refuse Field Sobriety Tests?

Many people do not realize that roadside field sobriety tests are different from breath or blood testing. The consequences and rules are not the same. Whether refusing was smart depends on the facts.

Some people try the tests because they think they will pass. Others refuse because they are nervous, injured, tired, or do not trust the process. Either way, the officer may still make an arrest if the officer believes there is probable cause.

Talk to a Montgomery County DWI Lawyer

Field sobriety tests can strongly affect a DWI case, but they should never be accepted blindly. The instructions, conditions, video, and medical facts all matter.

If you were arrested for DWI in Conroe, The Woodlands, Magnolia, Willis, or anywhere in Montgomery County, contact the Law Office of Timothy Rose or visit the firm’s DWI defense page.

Disclaimer: This article provides general information about Texas DWI defense. It is not legal advice and does not create an attorney-client relationship.