The Role of Field Sobriety Tests in DUI Cases: Can They Be Disputed?

When a police officer pulls someone over for suspected driving under the influence (DUI), field sobriety tests frequently play a pivotal role in determining whether an arrest will follow. These tests, conducted roadside, are designed to evaluate a driver’s balance, coordination, and ability to follow directions as potential indicators of impairment. Most people, however, are unaware of how these tests work—or how their results can be contested in court.

If you or someone you know has been charged with a DUI in Hampton, Virginia, understanding how field sobriety tests operate and their legal implications can be crucial to your defense. This blog will cover the basics of field sobriety tests, their reliability (or lack thereof), and how a skilled defense lawyer can challenge their findings in court.

Understanding Field Sobriety Tests

Field sobriety tests aim to give law enforcement an initial assessment of whether a driver is impaired. The National Highway Traffic Safety Administration (NHTSA) recognizes three standardized field sobriety tests (SFSTs) commonly used by officers during roadside stops.

The Horizontal Gaze Nystagmus (HGN) Test

The Horizontal Gaze Nystagmus test focuses on involuntary eye movement. An officer asks the driver to follow an object, like a pen or flashlight, with their eyes while holding their head steady. Jerky or erratic eye movement at certain angles, referred to as “nystagmus,” can indicate impairment. This test is based on the premise that alcohol consumption affects the smooth movement of the eyes.

The Walk-and-Turn Test

During the Walk-and-Turn test, the individual is instructed to take several heel-to-toe steps in a straight line, turn on one foot, and return in the same manner. This test evaluates the subject’s balance, ability to follow instructions, and coordination. Officers often look for indicators of impairment such as difficulty balancing, improper turning, or failing to walk heel-to-toe.

The One-Leg Stand Test

The One-Leg Stand test involves standing on one leg with the other foot slightly elevated while counting aloud. Officers observe for signs like swaying, raising arms for balance, hopping, or setting the foot down early—all considered evidence of potential impairment.

These three tests form the foundation of field sobriety evaluations. The NHTSA uses them because they are designed to assess specific physical and cognitive functions that alcohol may impair.

The Reliability of Field Sobriety Tests

While field sobriety tests are widely used, their reliability is far from absolute. Here are some critical factors that may question their accuracy:

Environmental Conditions

Roadside environments can be less than ideal for these assessments. Uneven or slippery pavement, poor lighting, bad weather, or distracting traffic can undermine a person’s ability to perform the tests—regardless of whether they are sober. For example, even dry pavement can have tiny inconsistencies that make walking heel-to-toe awkward.

Personal Physical and Mental Health

Not everyone is physically capable of performing these tests clearly. Medical issues, such as inner ear problems, arthritis, or past injuries, can compromise balance and coordination. Similarly, anxiety, stress, or fatigue—common feelings during a police stop—can lead to poor performance on tests that require focus and precise motor control.

Officer Training and Administration

The effectiveness of these tests also hinges on the officer’s preparation and adherence to proper protocol. If the officer administering the test lacks adequate training or fails to follow standardized procedures, the results may be unreliable. Misinterpreting results or providing confusing instructions can further distort the outcome.

Questioning Studies and Accuracy

Although the NHTSA claims that SFSTs are accurate indicators of impairment, studies reveal potential flaws. The HGN test is considered about 77% accurate, the Walk-and-Turn test 68% accurate, and the One-Leg Stand test 65% accurate when indicators of impairment are properly evaluated. This means that even when conducted under ideal conditions, these tests can produce false positives that unfairly incriminate sober individuals.

Challenging Field Sobriety Tests in Court

If you’ve been charged with a DUI in Hampton based on field sobriety test results, it’s important to know that you can challenge their validity in court. Effective legal defense strategies include questioning the circumstances, the administration of the tests, and their scientific reliability.

Legal Grounds for Disputing Field Sobriety Tests

Defense attorneys commonly challenge these tests on the grounds of incorrect procedures, environmental factors, or preexisting medical conditions. An officer’s failure to properly instruct the individual or to calibrate their observations with standardized guidelines can also be fertile ground for dispute.

Strategies for Disputation

• Cross-examining the arresting officer: Your lawyer may question the officer on whether proper protocols were followed or if external factors may have influenced the test results.
• Bringing in medical evidence: If physical conditions or past injuries could have affected your performance, these details can be submitted as evidence in your favor.
• Highlighting the science: Lawyers can introduce expert witnesses or studies demonstrating the inherent limitations and fallibility of SFSTs.
• Scrutinizing the training of the officer: Demonstrating that the officer lacked adequate training or credentials to administer SFSTs could weaken the prosecution’s case.

Successful DUI defenses often rely on experienced legal representation equipped to challenge the credibility of field sobriety tests.

Why Legal Representation Matters

Being charged with a DUI is a serious matter, and the results of field sobriety tests are often heavily relied upon by prosecutors. However, these results are not foolproof, and with the right legal expertise, they can be contested.

If you find yourself facing DUI charges in Hampton, Virginia, having a knowledgeable defense lawyer on your side can make a significant difference. Shannon & Associates, P.C. has extensive experience handling DUI cases and challenging field sobriety tests. Our team will work relentlessly to ensure your rights are protected and to seek the most favorable outcome for your case.

Take Action Today

Don’t leave your case up to chance. If you’ve been charged with a DUI and question the validity of field sobriety tests, it’s time to consult an experienced legal team. Call Shannon & Associates, P.C. today at (757) 228-5529 to schedule your consultation. We’ll work with you every step of the way to build a strong defense tailored to your situation.