The one leg stand is the third standardized exercise. You stand with your feet together, then raise one foot about six inches off the ground, point your toe, look at it, and count out loud, one thousand one, one thousand two, until the officer tells you to stop, which is about thirty seconds. Like the walk and turn, it is a divided attention exercise, and under State v. Meador, 674 So. 2d 826 (Fla. 4th DCA 1996), the officer describes your performance as a lay observation rather than a scientific score.
There are only four clues. The officer watches for swaying while you balance, for using your arms to balance, for hopping, and for putting your foot down before being told to stop. Two or more of those four is the training’s decision point, which is an even lower bar than the walk and turn. One genuine sway plus one instinctive arm raise, the things a sober person does when balancing on one foot at the edge of a road, can put you at the threshold.
Four clues over roughly thirty seconds. Two or more is the decision point, which means a single extra sway and one arm raise can be enough.
Thirty seconds is a long time to stand on one leg
The count runs to about thirty seconds, and standing on one leg for thirty seconds is harder than it sounds, especially for anyone who is tired, older, carrying extra weight, or wearing work boots. The validation assumed a fit person on a good surface. Add a sloped shoulder, gravel, passing traffic, headlights in your eyes, and the adrenaline of a traffic stop, and swaying is the expected human response, not evidence of a blood alcohol level.
The conditions and the exclusions
The procedure calls for the same kind of surface as the walk and turn, hard, dry, level, and non-slip, with adequate lighting so you have a frame of reference, and the officer is supposed to stand back about three feet rather than crowd you. The guidance also excludes the same groups, people over 65, people more than 50 pounds overweight, and people with conditions that affect balance, and lets anyone in heels over two inches remove their shoes. If your foot touches down, the officer is supposed to tell you to pick it back up and continue, not end the exercise on the spot.
Who NHTSA said should not be graded on this, in its own numbers
The other half of the problem is the clock. The research used a 30-second count, but the officer decides when the count stops, so a person can be held on one leg far past that, and the sway and the arms that come from simple fatigue late in a long hold get written down as the same clues that are supposed to mean alcohol. The manual even concedes the point in its own words, that tests which are difficult for a sober person to perform have little or no evidentiary value, and this is the hardest of the three to do sober. In the government’s own San Diego data, 41 percent of the drivers who were under the limit still showed two or more clues on it, so a “clue” here says far less than a jury assumes.
| Clue | A sober reason it happens |
|---|---|
| Sways while balancing | Almost everyone sways on one leg, and more so the longer it runs |
| Uses arms to balance | The natural reflex the body reaches for to stay upright |
| Hops | A tired supporting leg, or a slope or loose surface underfoot |
| Puts the foot down | Age, weight, footwear, an injury, or a count that ran long |
Two of these four is the decision point. Every one of them is something a sober person does when asked to balance on one leg on the side of a road.
What the numbers showed
Even under ideal conditions, the one leg stand was never a precise instrument. In the original validation, scoring two or more clues classified people correctly only about 65 percent of the time, which means roughly one in three were misclassified. As an NHTSA-qualified instructor, I put that number, the roadside conditions, and any physical reason you might sway in front of the jury, so a single arm raise on a gravel shoulder is not allowed to stand in for proof beyond a reasonable doubt.
On this one I look first at who was asked to do it and for how long. I go through your age, your weight, your shoes, and any back, leg, or ear trouble against the cautions NHTSA printed itself, and I watch the video for how long the officer really kept you balancing before writing down a clue. I teach this battery, so I can hold up the agency’s own limits and its own words next to what happened to you. When a 30-second exercise runs long on a person the manual said should not be graded this way, two clues out of four tells a jury one honest thing, that standing on one leg is hard.
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.
A 65 Percent Test Scored in 30 Seconds
NHTSA’s research assigns this exercise the weakest number of the three original classification rates: two or more of its four clues classified about 65 percent of suspects correctly against a 0.10 standard, with the 1998 San Diego study publishing 83 percent at 0.08. Swaying counts. Using your arms counts. Hopping counts. Putting your foot down counts. Two of those in thirty seconds, on the side of a road, and the scoring says over the limit.
The published figure is the flattering one. Calculated from the San Diego study’s own tables, 31 of the 75 tested drivers who were below 0.08 were flagged as over, a 41.3 percent false positive rate. The training materials themselves acknowledge that age, weight, footwear, and physical condition affect performance. When the video shows a composed driver who swayed once and steadied a wobble with an arm, the clue count and the reality on screen tell two different stories, and the jury gets to compare them.
Questions About the One Leg Stand
What is the one leg stand test?
You raise one foot about six inches off the ground, look at your toe, and count out loud until told to stop, which is about thirty seconds. It is a divided attention exercise, and the officer watches for four clues while you balance.
How many clues are on the one leg stand?
Four: swaying while balancing, using your arms to balance, hopping, and putting your foot down early. Two or more is the training's decision point, which is a low threshold that an ordinary sway and one arm raise can reach.
Is it hard to do even when sober?
Yes. Holding one leg up for thirty seconds is difficult for anyone tired, older, heavier, or in stiff shoes, and a sloped roadside, gravel, headlights, and the stress of a stop all make swaying the normal response rather than a sign of alcohol.
Who should not be given the one leg stand?
The procedure excludes people over about 60, people more than 50 pounds overweight, and people with conditions that affect balance, and it lets anyone in heels over two inches remove their shoes. Grading an excluded person is a strong point for the defense.
How accurate is the one leg stand?
Not very. In the original validation, two or more clues classified people correctly only about 65 percent of the time, so roughly one in three were misclassified, and that was under controlled conditions rather than a real roadside.
How do you challenge it?
I check the surface, the lighting, your footwear, and any physical condition against the NHTSA procedure, review the bodycam, and show the jury why a sway or an arm raise here is an expected human reaction, not proof of impairment.
Related: the walk and turn, the HGN eye test, the NHTSA standard and accuracy, medical conditions, and the roadside conditions.
Does my age or weight matter on the one leg stand?
Yes. NHTSA’s own research warned that people over 65, anyone with a back, leg, or middle-ear condition, and people 50 or more pounds overweight had difficulty with this exercise, and that heels over two inches should come off first. When the officer ignores those cautions, the result is unreliable from the start.
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.
