Understanding the Role of Field Sobriety Tests in DWI Arrests

You’re driving through gorgeous Beaufort with the windows down, the scent of salt air swirling through your car. Then, blue lights in your mirror. Minutes later, you’re on the side of the road, balancing on one foot with a pounding heart. An officer has asked you to perform a field sobriety test, meaning you’ll be required to complete physical and cognitive exercises to assess your level of impairment. You’re not drunk, just tired and anxious. You might be wondering, How do field sobriety tests work? What happens if I fail one? In that moment, understanding your rights during a DWI stop and the role of field sobriety tests in DWI arrests can make all the difference.

What Does a Field Sobriety Test Include?

A field sobriety test involves tasks that assess a driver’s physical and mental abilities to detect potential impairment by alcohol or drugs. The National Highway Traffic Safety Administration (NHTSA) developed the widely used standardized field sobriety tests (SFST).

What Are the 3 Standard Field Sobriety Tests?

The SFST includes three tests:

• Horizontal gaze nystagmus (HGN). The officer tracks your eye movement as you focus on a moving object in front of you while keeping your head still. 
• Walk-and-turn (WAT). You walk heel-to-toe along a straight line, turn, and repeat. This test assesses coordination and the ability to follow instructions.
• One-leg stand (OLS). You stand on one foot while counting aloud for a set period of time, often 30 seconds. 

These tests give officers a structured way to evaluate suspected impairment, but they rely heavily on observation and interpretation.

What Do Police Look for in a Field Sobriety Test?

Each test has specific “clues” police use to support a decision to arrest:

• HGN—involuntary jerking as eyes move to the side, especially if it starts before eyes reach a 45-degree angle or when looking as far to the side as possible;
• WAT—stepping off the line, losing balance, using arms, or turning incorrectly; and
• OLS—swaying, putting your foot down, or needing your arms for balance.

While these behaviors could indicate impairment, factors like fatigue, anxiety, medical conditions, or uneven ground can also lead to similar results. These tests are subjective, and mistakes can happen.

How Field Sobriety Tests Are Used in North Carolina

It is illegal to drive while noticeably impaired or with a blood alcohol concentration (BAC) of 0.08% or higher. Failing an SFST, meaning you demonstrate signs of poor balance, coordination, or focus, could give the officer probable cause to make a DWI arrest—even before a breathalyzer or blood test is conducted. 

Do You Legally Have to Do a Field Sobriety Test?

Field sobriety tests are voluntary, meaning drivers are not required to take them. Yet many comply because they don’t realize participation is voluntary.

Refusing to take one will not result in automatic license suspension. Refusing a field sobriety test does not carry the same immediate legal repercussions as refusing a chemical test like a breathalyzer. Unlike a chemical test refusal, which triggers automatic license suspension under implied consent laws, the penalties for refusing a field sobriety test are not as severe.

Law enforcement officers in Beaufort and Carteret County are trained to conduct SFSTs during DWI investigations, and how you perform these tests can significantly impact the likelihood of your arrest.

How Accurate Are Field Sobriety Tests?

Field sobriety tests may look scientific, but they’re built on human observation. According to various studies, the HGN test is about 77% accurate, the WAT is about 68%, and the OLS is roughly 65%. When all three are combined, the accuracy can reach 91%—but that assumes ideal conditions and perfect execution.

In reality, roadside tests often happen at night, on uneven ground, and with nervous drivers. Weather, health conditions, and even your shoes can distort results. While the role of field sobriety tests in DWI arrests is to help justify DWI arrests, they’re also vulnerable to human error—making them far from conclusive.

What Happens After a DWI Arrest?

North Carolina imposes strict penalties for DWI, including fines, license suspension, jail time, and mandatory substance abuse treatment. Penalties increase if you have prior convictions, a BAC above 0.15%, or aggravating factors, like transporting a minor during the offense. In the case of repeat DWI arrest, your case may be heard in a DWI treatment court, where you may be required to complete a treatment or counseling program.

Don’t Surrender to a DWI. Take Control

Don’t face the legal system alone if you’ve been charged with DWI in Beaufort or Carteret County. At Tetterton Law Firm, PLLC, we focus exclusively on criminal and traffic defense and understand how to challenge questionable field sobriety test results.

We know the local courts, prosecutors, and law enforcement procedures and use that insight to protect your rights.

Contact us for a confidential consultation. Let’s take back control of your defense starting today.

Resources:

• Accuracy of Field Sobriety Tests. Field Sobriety Tests.org, link
• Statistical Evaluation of Standardized Field Sobriety Tests. U.S. Department of Justice. (2005), link
• The Standardized Field Sobriety Tests (SFST) and measures of cognitive functioning. Science Direct (2015), link
• Field Sobriety Test Review. Texas District & County Attorneys Association, link
• Driving and Alcohol. North Carolina Department of Public Safety, link
• North Carolina G.S. § 20-16.2, link.