The finger dexterity test (also called the finger-count or finger-to-thumb test) asks you to touch the tip of your thumb to each fingertip in sequence while counting. It seems trivial, which is part of the problem. I am Joel Brand, and here is what the officer is really doing and why this test carries little weight.
How it is administered
You touch your thumb to the tip of each finger, often counting "one, two, three, four" forward and back, for a set number of repetitions. The officer watches your coordination, your counting, and whether you can follow the instructions, treating it as a divided-attention task that combines a fine-motor movement with a counting sequence under the pressure of a roadside stop.
It is not a standardized test
Like the alphabet and Romberg tests, this is not one of the three NHTSA-standardized field sobriety tests (HGN, walk-and-turn, and one-leg stand). There is no validated scoring and no scientific basis for treating a fumble as proof of intoxication. The non-standardized status is not a technicality; it means the test was never subjected to the validation research that even the flawed standardized battery underwent, so there is nothing tying a particular performance to a particular level of impairment.
Why fine-motor tasks are a poor measure
Fine-motor coordination is exactly the kind of ability that varies enormously between people for reasons having nothing to do with alcohol. Manual dexterity differs by age, by occupation, by the presence of arthritis or a prior hand injury, and by how cold the person's hands are at the roadside. Some perfectly sober people simply are not coordinated at a quick, unfamiliar finger-counting task performed on command. Because there is no baseline for how a given individual performs sober, the officer has no way to know whether a fumble reflects alcohol or just that person's ordinary coordination under stress.
Why it is unreliable
Coordination on a fine-motor task varies enormously between sober people and is affected by nerves, cold hands, arthritis, injuries, and simple unfamiliarity with an odd request given under stress on the side of the road. The "scoring" is entirely the officer's subjective impression, with no defined threshold for how many miscounts or fumbles supposedly indicate impairment. What gets written into the report as a clue is, in reality, one person's opinion about a task most people have never practiced.
Conditions at the scene matter
The setting in which this test is given makes it even less reliable. Roadside conditions, poor lighting, an uneven surface, cold weather, passing traffic, and the glare of headlights all interfere with concentration and physical performance. Add the adrenaline of a police encounter, and a task that would be easy in a calm, warm room becomes genuinely difficult for a sober person. I look closely at exactly where and how the test was administered, because the conditions frequently explain the very performance the officer attributes to alcohol.
Why officers use it anyway
If this test proves so little, why do officers still administer it? It is fast, needs no equipment, and gives the officer another item to record in support of an arrest decision. Like the other non-standardized tests, it functions less as a neutral scientific measurement and more as a way to build a record that justifies the stop turning into an arrest. Seeing it for what it is, a quick, subjective add-on rather than a reliable indicator of impairment, is the first step to challenging how much weight a prosecutor can fairly put on it.
How it fits the bigger picture
The finger dexterity test rarely carries a case by itself. The prosecution stacks it alongside the driving pattern, the officer's observations, the standardized tests, and any chemical result, hoping the accumulation suggests impairment. Discrediting this piece matters because each weak link removed makes the overall impression less persuasive and pushes attention back to the evidence that actually decides DUI cases, above all the reliability of the chemical test. When a fine-motor task with no validated scoring is shown to be the officer's subjective impression, it stops doing the work the prosecution wanted it to do.
How I challenge it
These tests are scored on an officer's opinion, and that opinion is what I take apart: deviations from the standardized instructions, the conditions at the scene (lighting, slope, traffic, your footwear), your age, weight, and any injury or medical condition, and the innocent reasons a sober person stumbles on the side of a road. It rarely stands alone, and discrediting it weakens the whole impairment case. See the unfair field sobriety test defense and my top DUI defenses.
What the recording usually shows
The body-cam and dash-cam footage often tells a very different story than the report. A report may say a defendant "failed to keep count" or "lost the sequence," while the video shows someone whose hands were visibly cold, who was distracted by traffic, or who simply performed an unfamiliar task imperfectly the way most sober people would. I obtain the footage in every case, because comparing what the officer wrote to what the camera captured frequently exposes just how subjective and shaky this kind of test really is.
Why it should not anchor a case
Given everything, a finger dexterity result should never be the anchor of a DUI case, and when the prosecution leans on it, that reliance is itself a sign of a weak case. A test with no validated scoring, performed once, under stress, in poor conditions, on an unfamiliar task, simply cannot bear much weight. The more the prosecution emphasizes this test, the more it suggests the genuinely probative evidence, the driving and the chemical result, is not as strong as the state would like, which is exactly the opening a careful defense looks for.
You can decline field sobriety tests
For drivers 21 and over, the roadside tests are generally voluntary, and there is usually no penalty for politely declining. That is very different from the post-arrest chemical test, which is not optional. I explain the distinction in whether to refuse field sobriety tests. Compare the others: the HGN eye test, walk and turn, and one-leg stand.
Did a roadside test help convict you? Let's look.
If a field sobriety test is driving the case against you, it deserves a hard, informed challenge. Use the free case analysis on this page, or call me directly at (888) 271-6644. I answer my own phone, 24/7.