What Defenses Are Most Effective in DUI Cases Involving Field Sobriety Tests?
March 19, 2026
Being arrested for driving under the influence is stressful, especially when you have to undergo a field sobriety test. Officers often rely on these roadside exercises to build a DUI case, but those tests aren’t always as reliable as they appear.
At Schwartz, Hanna & Olsen, P.C., we don’t assume the officer’s conclusions are accurate in a DUI case. Instead, we review the facts, the procedures, and the conditions surrounding the stop to determine which defenses may be most effective. A strong DUI defense often begins with challenging how the field sobriety test was administered and interpreted.
With offices in South Plainfield, Hamilton Township, and Somerville, New Jersey, as well as Mineola, New York, we serve clients throughout Middlesex, Somerset, Morris, Essex, Passaic, Bergen, Sussex, and Hunterdon County. Contact us today to schedule a free consultation.
Defense 1: Challenging the Legality of the Stop
Before addressing field sobriety tests, it's essential to examine whether the traffic stop itself was lawful. If the officer lacked a valid reason to pull you over, the entire DUI case may be dismissed. Police must have reasonable suspicion that a traffic violation or criminal offense occurred. If the stop was based on a vague hunch or an unverified tip, that may not be enough. Some common stop-related defenses include:
Lack of reasonable suspicion: If there’s no clear traffic violation or observable behavior supporting impairment, we may argue that the stop violated constitutional protections.
Improper checkpoint procedures: DUI checkpoints must follow strict guidelines. If law enforcement failed to follow those protocols, any evidence gathered during the stop may be challenged.
Mistaken identity of the driver: In some situations, law enforcement officers may not clearly identify the driver before initiating a stop.
When a stop is invalid, the evidence gathered afterward, including field sobriety tests, may not be admissible in court. That’s often the first critical step in defending a DUI case.
Defense 2: Questioning the Administration of Field Sobriety Tests
If the stop was lawful, your next available defense is whether the field sobriety tests were conducted correctly. These tests are standardized by the National Highway Traffic Safety Administration (NHTSA), and police officers are required to follow specific procedures. The three standardized tests typically include:
Horizontal gaze nystagmus test: This measures involuntary eye movements as you follow an object.
Walk-and-turn test: This requires heel-to-toe steps along a straight line with specific instructions.
One-leg stand test: This involves standing on one foot for a set period while counting aloud.
If the officer deviates from proper instructions or scoring methods, the results may be unreliable. Officers could rush instructions, demonstrate the test incorrectly, or fail to account for medical conditions. When procedures aren’t followed carefully, the reliability of the test results can be questioned.
Defense 3: Environmental and Physical Factors
Field sobriety tests are often conducted on the side of a busy road, late at night, and under less-than-ideal conditions. These external factors can significantly affect your performance, even if you haven’t consumed alcohol. Some common defenses could include:
Poor lighting or uneven pavement: Gravel, sloped shoulders, or potholes can interfere with balance-based tests.
Weather conditions: Rain, wind, or extreme cold can affect coordination.
Traffic distractions: Passing vehicles and flashing lights can make it difficult to concentrate.
Medical conditions: Inner ear disorders, back injuries, neurological issues, or even anxiety can impact balance and coordination.
Age and physical limitations: Older individuals or those with mobility concerns may struggle with these physical tasks regardless of sobriety.
When these factors are presented in court, you and your attorney can show that poor performance on a roadside test doesn’t automatically equal impairment. In many instances, raising these issues creates reasonable doubt in a DUI case.
Defense 4: Subjectivity and Officer Bias
Even when field sobriety tests are performed according to the guidelines, they still involve a degree of subjectivity. Officers are trained to look for “clues” of impairment, but those clues aren’t always clear-cut. For example, during the walk-and-turn test, an officer may mark someone down for starting too soon, missing heel-to-toe contact, stepping off the line, or using their arms for balance.
However, slight missteps can happen for many reasons unrelated to alcohol. In a DUI case, we often review dashcam or body camera footage to see whether the officer’s written report accurately reflects what occurred. If video evidence contradicts the officer’s description, that discrepancy can significantly weaken the prosecution’s position.
Defense 5: Miranda Warnings and Statements
Following a field sobriety test, law enforcement will often ask additional questions or request chemical testing. If you made statements during this process, we can examine whether you rights were protected. The key issues that can be used in your defense include:
Failure to provide Miranda warnings when required
Coercive questioning tactics
Confusion about the right to refuse certain tests
If your constitutional protections were violated, any statements you made during the stop could be suppressed. Suppressing incriminating statements can shift the direction of a DUI case and significantly affect the prosecution’s strategy.
Defense 6: A Lack of Corroborating Evidence
Field sobriety tests are only part of the prosecution’s case. If there’s no strong corroborating evidence, such as erratic driving, slurred speech, or a failed breath test, the case may rely heavily on subjective observations. Common missing corroborating evidence may include:
No video evidence of poor driving
Clear speech and normal behavior during the stop
Low or borderline breath test results
Inconsistent police reports
When the evidence doesn’t align with the charge, we can argue that the field sobriety results alone aren’t enough to prove impairment beyond a reasonable doubt. That approach often becomes central to defending a DUI case in court.
Contact Our DUI Defense Lawyers in New Jersey and New York Today
Facing a DUI charge can be stressful, but there are ways you can defend against the charges and challenge the evidence. At Schwartz, Hanna & Olsen, P.C., we are determined to review every detail of your case and explain your options. If you’re facing a DUI charge, contact us today to schedule a free consultation and discuss your situation.
With offices in South Plainfield, Hamilton Township, and Somerville, New Jersey, as well as Mineola, New York, we serve clients throughout Middlesex, Somerset, Morris, Essex, Passaic, Bergen, Sussex, and Hunterdon County. Call today.