Prince William County Field Sobriety Tests

Field sobriety tests are a series of roadside evaluations that police may use to confirm or falsify their suspicions of a driver’s impairment. The most common field sobriety tests are the horizontal gaze nystagmus, nine-step walk and turn, and one leg stand. These three field sobriety tests used in Prince William County have been standardized by the National Highway Traffic Safety Administration (NHTSA) and may be used at an officer’s discretion during DUI stops and checkpoints.

The Horizontal Gaze Nystagmus

A horizontal gaze nystagmus, or HGN, involves an officer holding a pen or some other object in front a person’s face. They would move that object left to right and watch how well the driver’s eyes track it.

A person who is under the influence of drugs or alcohol may be unable to smoothly follow an object in motion and is likely to have a delayed or lagging visual response. Anything other than a smooth pursuit of an officer’s pen would indicate impairment to law enforcement.

When performing this field sobriety test, Prince William County police will instruct a person to keep their head still while they attempt to follow the object. Doing so allows an officer to focus on their eyes and whether they track the object smoothly. If there is a lack of smooth pursuit, police will count that against them in their investigation.

Nine-Step Walk and Turn

The nine-step walk and turn test requires a person to stand with one foot directly in front of the other and touching heel to toe. They have to hold that position for a period of time while police instruct them on how to perform the remainder of the test.

Once told to begin, a driver must take nine heel-to-toe steps and follow a line ⁠— either imaginary or painted on the road. After the nine steps, they must turn around and return back to the starting location using nine heel-to-toe steps. During this test, a person must keep their hands at their sides and count aloud for each step they take. Once complete, an officer will document any discrepancies in the driver’s test performance in their field notes, which may ultimately be presented at trial to the prosecutor.

The One Leg Stand Test

A driver undergoing the one leg stand test must stand at attention with their hands at their sides while raising one foot six inches above the ground. It is important to keep their foot parallel to the ground while is it is raised. They must then hold that position as steady as they can for 30 seconds while counting aloud. They cannot hop or use their arms for balance for the entirety of those 30 seconds.

Regulations for Administering Field Sobriety Tests

These three tests have been standardized by NHTSA and must be described, demonstrated, and evaluated uniformly in every jurisdiction. Every officer in Prince William County is trained on how to administer these tests and knows what to look for, how to demonstrate them, and how to evaluate them.

Standardizing field-testing helps eliminate subjectivity in an officer’s evaluation of a person’s fitness to continue driving. Therefore, any deviation from how Prince William County field sobriety tests are typically performed may jeoporadize their validity and strength.

Refusing to Perform Field Sobriety Tests in Prince William County

A person can refuse to participate in a field sobriety test at anytime. However, a refusal could indicate to the courts that a driver is afraid of what the test will reveal. Prosecutors may cite a person’s refusal to participate in a field sobriety test as evidence of their guilty conscience.

Although, compliance with the tests may lead to meaningful evidence against them. This has led to a great deal of legal debate among lawyers who practice this area of law. Every person has the right to refuse Prince William County field sobriety tests at any time, as no one is obligated to provide evidence or testimony against themselves even when under the direction of an officer.