When an officer says you took the standardized field sobriety tests, that means three specific exercises and nothing else: horizontal gaze nystagmus, the walk and turn, and the one leg stand. These are the only three the National Highway Traffic Safety Administration studied, validated, and gave a fixed procedure. Under State v. Meador, 674 So. 2d 826 (Fla. 4th DCA 1996), the two physical exercises come in as the officer’s lay observations, while horizontal gaze nystagmus is scientific evidence that needs a predicate.
Standardization is the spine of all three. NHTSA’s manual is explicit that the exercises are only valid when they are administered in the prescribed, standardized way, and that changing any element compromises the validity. That single rule is why how the exercise was given matters at least as much as how you performed.
The three exercises NHTSA studied and standardized. The clue counts are fixed, and so is the procedure that makes them mean anything.
Three exercises, three different attacks
Each exercise has its own procedure, its own clues, and its own weak points. Horizontal gaze nystagmus asks the officer to watch your eyes for an involuntary jerk and to find up to six clues, and it is the one Florida treats as science. The walk and turn splits into an instruction stage and a walking stage, with eight clues spread across both. The one leg stand runs about thirty seconds and has four clues. We treat each one separately, because the way to challenge an eye exercise is nothing like the way to challenge a balance exercise.
Standardization is the spine
The reason every page here keeps returning to administration is that the validity studies were run under controlled conditions, with trained administrators following the procedure to the letter. The roadside is not that. When the surface slopes, the line is imaginary, the demonstrations are skipped, the instructions are garbled, or the timing is wrong, the officer has stepped outside the only conditions under which these exercises were ever shown to predict anything. In Florida those deviations usually go to the weight of the evidence rather than keeping it out, which means the fight happens at cross-examination and in front of the jury.
I started out as an Assistant Public Defender in Florida’s Thirteenth Judicial Circuit, in Tampa, and today I am one of six ACS-CHAL Forensic Lawyer-Scientists in Florida and an NHTSA-qualified field sobriety instructor. I was trained to administer this battery and to teach the officers who give it, so I can stand in front of a jury and show the exact point where the roadside exercises in your case left the standard. Learn more about my background.
Questions About the Standardized Tests
What are the three standardized field sobriety tests?
Horizontal gaze nystagmus, the walk and turn, and the one leg stand. These are the only three the National Highway Traffic Safety Administration studied and gave a fixed, validated procedure. Everything else an officer asks you to do at the roadside is non-standardized.
Are the standardized tests scientific?
Only one is treated that way in Florida. Under State v. Meador, horizontal gaze nystagmus is scientific evidence that requires a predicate, while the walk and turn and the one leg stand come in as the officer's lay observations of how you moved.
How accurate are they?
Less than they sound. The original validation classified horizontal gaze nystagmus correctly about 77 percent of the time, and the walk and turn and one leg stand lower than that, and only when administered perfectly under controlled conditions.
What is the most common defense?
Administration. The exercises are valid only when given in the exact standardized way, so the most common and effective attack is showing the officer departed from the trained procedure, which moves the result away from the only conditions where it was ever validated.
Why does it matter that you teach these tests?
Because I can read the officer's performance against the manual the officer was trained on. As an NHTSA-qualified instructor I know each required step and each scored clue, so I can show a jury exactly where the standardized procedure broke down.
Related: the field sobriety overview, why the results are unreliable, HGN and drugs, the one leg stand, and the NHTSA standard.
This page is general information, not legal advice, and it does not create an attorney-client relationship. Field sobriety exercises in Florida are governed by case law and by section 316.193, Florida Statutes. Procedures and rules change, and every case turns on its own facts. Past results do not guarantee a similar outcome.
