Most people who submit to field sobriety tests during a traffic stop walk away believing those results have sealed their fate. If the officer wrote “failed” in the arrest report, the case must be open and shut. That assumption is exactly what the prosecution counts on, and it’s one of the first things we challenge. Our criminal defense attorney is a former prosecutor who worked in the Newport News Commonwealth’s Attorney’s Office, where he built DUI cases from the other side of the courtroom. He knows precisely where they break down.
Field sobriety tests aren’t the objective measurements most people imagine them to be. They’re physical exercises administered roadside, often at night, under stressful conditions, scored by a single officer using a standard that NHTSA itself acknowledges is imperfect even under ideal circumstances. Understanding what these tests actually measure and where they fail is the foundation of a serious defense.
What Field Sobriety Tests Are Actually Measuring
Virginia law enforcement relies on three tests developed and validated by the National Highway Traffic Safety Administration: the Horizontal Gaze Nystagmus test, which checks for an involuntary jerking of the eye associated with alcohol impairment; the Walk-and-Turn; and the One-Leg Stand. These three make up the Standardized Field Sobriety Test battery, and they’re the only FSTs backed by formal research with meaningful evidentiary weight in court.
Even so, NHTSA’s own validation data places the accuracy ceiling of the full three-test battery at roughly 82% for detecting a BAC of 0.08 or higher, and that figure applies only under ideal conditions with proper administration. Statistically, about one in five results can point to impairment when none exists. Non-standardized tests, such as alphabet recitation or a finger-to-nose exercise, aren’t NHTSA-endorsed, and their results aren’t typically admitted as evidence in Virginia DUI prosecutions.
Your Right to Refuse & Why It Matters
Field sobriety tests are voluntary under Virginia law. You aren’t legally required to perform them, and Virginia courts have confirmed this in cases including Hammond v. Commonwealth, 17 Va. App. 565 (1994) and Jones v. Commonwealth, 279 Va. 52 (2010). Refusing the roadside exercises carries no automatic license penalty. Under Jones, refusal can’t be treated as evidence of consciousness of guilt, though Virginia courts have recognized it may be weighed as one factor among many in a probable cause determination.
That right is entirely separate from Virginia’s implied consent law under Code 18.2-268.2, which governs post-arrest chemical testing. Once you’ve been arrested for DUI, refusing the breath or blood test triggers an immediate civil license suspension and can be introduced at trial. The roadside preliminary breath test, sometimes called a PBT, falls in a different category: it’s also voluntary, and under Virginia Code 18.2-267(E), the result isn’t admissible as evidence in a Newport News DUI prosecution. Officers sometimes present the PBT and the standardized tests as if they carry equal weight. They don’t.
How FST Results Can Be Challenged
A challenge to field sobriety test results usually starts with the footage. NHTSA’s own administration manual states that if any element of the standardized test is changed, the validity of the result is compromised. That standard applies to the officer’s instruction sequence, the physical demonstration, and the scoring criteria. Body camera and dashcam recordings often show deviations that never appear in the written arrest report.
The physical setting matters more than most people realize. Uneven pavement, loose gravel, passing traffic, and the strobing effect of cruiser lights during a Horizontal Gaze Nystagmus test can all affect performance independent of alcohol. Inner ear disorders, orthopedic injuries, neurological conditions that cause baseline nystagmus, and certain prescription medications can produce exactly the signs officers are trained to associate with impairment. We review medical history and the conditions at the scene as part of every defense evaluation.
When an officer orders a driver to perform field sobriety tests rather than asking, the line between voluntary consent and coercion becomes legally significant. If a driver reasonably believed they had no choice but to comply, we can argue the results weren’t freely given and may seek to suppress them under the Fourth Amendment. That argument requires specific facts from the stop, which is another reason the footage and the officer’s exact language matter.
What a Successful Challenge Can Mean for Your Case
Challenging FST results can take two distinct forms. The first is a pretrial motion to suppress, asking the court to declare the test results inadmissible before trial begins. The second is a trial argument that the results deserve little weight given the specific circumstances of the stop, the officer’s deviations from protocol, or the driver’s physical condition. Both are legitimate strategies, and the right approach depends on the facts.
Virginia courts do allow officer testimony about a driver’s field sobriety performance even when tests were improperly administered, so pointing to a procedural flaw alone is rarely enough. The challenge has to be built on concrete evidence: the footage, the officer’s training records, the road conditions, and any medical documentation. In Newport News General District Court, located at 2500 Washington Avenue, FST evidence is weighed alongside breath or blood test results and the officer’s testimony. Undermining it can weaken the probable cause underlying the arrest itself or reduce the persuasiveness of the prosecution’s case in ways that create real leverage.
Why a Former Prosecutor Sees These Cases Differently
When our attorney was working in the Newport News Commonwealth’s Attorney’s Office, he assembled DUI cases for prosecution. He knows which parts of an FST record a prosecutor considers strongest and where officers’ administration practices most often fall short of what the NHTSA manual requires. That background shapes how we evaluate whether the Commonwealth’s case is as solid as the arrest report makes it appear.
A failed field sobriety test isn’t the end of the road. The 82% accuracy ceiling, the voluntary nature of the tests, the environmental and medical variables, the coercion question, and the gap between what the officer wrote and what the footage shows all represent real opportunities for a defense that goes beyond accepting the arrest report at face value. Ehrenworth Law, PLLC has represented clients in Newport News and throughout the Hampton Roads area since 1998, and we’re available around the clock to start reviewing your case. Call (757) 663-4477 for a free consultation.