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In Focus: Challenging the Results of Field Sobriety Tests
Field sobriety exercises are one part of a DUI investigation. Standardized testing has a research basis, but performance and officer interpretation remain open to case-specific challenge. There is no universal rule that every exercise lacks scientific support or may never be called a test in court.
How are Field Sobriety Exercises Conducted?
The most common standardized field sobriety exercises include:
- One Leg Stand — The driver is instructed to raise one leg six inches off of the ground, look at the raised foot and count out loud until instructed to stop, to determine if the driver’s balance is affected by impairment.
- Walk and Turn — The driver is instructed to take nine heel to toe steps along a straight line, turn and repeat all while looking at your feet and keeping your arms by your side.
- Horizontal Gaze Nystagmus (HGN) — The officer observes how the driver’s eyes react to external stimuli such as following a pen with your eyes without moving your head.
How can I challenge the results of a field sobriety exercise?
If you have been charged with DUI based on the results of field sobriety exercises, this does not mean that a conviction is inevitable. Because these are subjective exercises that are subject to human error, the results can be challenged in a number of ways.
First, it may be possible to question the training and experience of the police officer who administered the exercise. If the officer improperly administered the exercise, then the results may be flawed. Additionally, having a physical condition, such as a disability, ear infection, vision problems, or other issues affecting equilibrium and balance, may skew field sobriety exercise results.
Finally, the officer must provide proper instructions on how to perform the exercise, and also consider the lighting, terrain, and relevant weather conditions at the time the exercise is being administered. If the police provide inadequate instructions or the road is poorly lit or uneven, the results of the field sobriety exercise can be challenged.
Standardized Exercises Have Limits
NHTSA training materials describe a standardized battery of horizontal gaze nystagmus, walk-and-turn, and one-leg-stand tests and the research supporting their use under specified conditions. They are not infallible, do not directly measure blood-alcohol concentration, and should not be treated as automatic proof of guilt. Nonstandard exercises do not necessarily share the same validation.
Reliability depends on the exercise, instructions, administration, scoring, and individual circumstances. An attorney can compare the officer’s report with video, training, and the applicable protocol.
Issues Worth Examining
- Whether instructions and demonstrations followed the required protocol.
- Whether the surface, lighting, weather, footwear, or nearby traffic affected performance.
- Whether injury, balance problems, age, medication, hearing, language, or another condition provides an alternative explanation.
- Whether the reported clues match the video and were scored correctly.
Flashing lights and moving visual stimuli may matter to particular observations, but they do not automatically invalidate every exercise. A medical condition or administration error may affect weight, admissibility, or probable cause; suppression is not guaranteed. Permitted testimony and terminology depend on the test, foundation, governing law, and the judge’s rulings.
Physical Exercises Versus Chemical Tests
Roadside exercises are different from breath, urine, or blood testing under Florida’s implied-consent law. Refusing a physical exercise does not itself trigger the chemical-test-refusal suspension, but may have evidentiary consequences. Chemical-test refusal has separate statutory prerequisites and consequences. Do not assume the same advice applies to every kind of test.
The Takeaway
In the end, being charged with DUI is serious matter because a conviction can lead to a loss of your driving privileges, fines, and, depending on the circumstances, imprisonment. When it comes to challenging field sobriety exercise, it is crucial to enlist the services of an experienced DUI defense attorney.