If you were arrested for DUI, an officer almost certainly asked you to perform a series of roadside exercises: walk a line, stand on one leg, follow a pen with your eyes. Those are field sobriety tests, and the officer wrote down that you "failed." Here is what most people do not realize, and what I want every client to understand: these tests are subjective, they are administered under terrible conditions, and they are designed in a way that lets a completely sober person fail them. I am Joel Brand, and challenging unfair field sobriety testing is one of the most reliable ways I weaken a California DUI.
The tests are built to produce "clues," not truth
A field sobriety test is not a pass/fail exam in the way you would expect. The officer is trained to watch for a list of small "clues," and only a couple of them count as failing. On the walk-and-turn, two clues out of eight is a fail. On the one-leg stand, two out of four. That means a single stumble, a moment of arm-raising for balance, or starting a beat too early can be written up as evidence of intoxication. The deck is stacked before you take a single step.
Only three tests are even standardized
The federal government, through the National Highway Traffic Safety Administration (NHTSA), recognizes only three "standardized" field sobriety tests: the horizontal gaze nystagmus (HGN) eye test, the walk-and-turn, and the one-leg stand. Even those were validated only at limited accuracy rates and only when administered exactly according to protocol. Any other roadside exercise an officer uses, the Romberg balance test, the finger-count test, or reciting the alphabet, has no scientific validation at all. When the prosecution leans on a non-standardized test, that is an immediate target.
The conditions almost never match the laboratory
The accuracy numbers NHTSA reports come from controlled settings. Your test did not happen in a controlled setting. It happened on the shoulder of a road, probably at night, likely with traffic rushing past, patrol lights strobing in your eyes, on pavement that may have been sloped, cracked, gravelly, or wet. You may have been cold, exhausted, frightened, and wearing dress shoes, boots, or heels. Every one of those factors degrades performance, and none of them has anything to do with alcohol. A test that is unreliable in a lab is far less reliable on the side of Highway 101 at 1 a.m.
Some people simply cannot pass
NHTSA's own materials acknowledge that certain people should not be expected to perform these tests normally even when sober. That includes people over 65, people who are roughly 50 or more pounds overweight, and people with back, leg, hip, knee, or inner-ear problems. Add neurological conditions, vertigo, anxiety, fatigue, and the fact that English may not be your first language, and you have a long list of innocent explanations for a "failed" test. I look closely at your physical condition and medical history, because they frequently rewrite what the officer's report claims to show. See medical conditions that can affect a DUI.
Officers make the tests even less reliable
The standardized tests are only valid if they are given in the standardized way, and in the real world they often are not. Officers rush the instructions, demonstrate incorrectly, use the wrong stimulus distance on the eye test, fail to account for the surface, and score ambiguous movements as clues. There is also a powerful confirmation bias at work: by the time the tests start, the officer usually already suspects you are impaired, and that belief colors how every wobble gets recorded. When the body-camera video and the written report do not match, that gap is where I go to work.
How I challenge field sobriety evidence
I obtain and study the dash-cam and body-cam footage frame by frame and compare it against the officer's report and the NHTSA manual. I cross-examine the officer on the exact protocol, the conditions, your physical limitations, and every deviation from how the test was supposed to be run. Where it helps, I bring in an expert to explain to the jury just how shaky these tests are. The goal is to show that the "failure" reflects the test and the conditions, not your sobriety, which also undercuts the officer's probable cause to arrest and can support a broader challenge to the stop. See my top DUI defenses and the most common police mistakes at a DUI stop.
Remember: you could probably have said no
One last point that surprises people. For drivers 21 and over, field sobriety tests are generally voluntary, and there is usually no penalty for politely declining them. That is very different from the post-arrest chemical test, which is mandatory. Officers are not required to tell you the roadside tests are optional, and they rarely do.
Why "passing" is almost impossible by design
Step back and look at the scoring and the unfairness becomes obvious. On the walk-and-turn, two clues out of eight is a fail. On the one-leg stand, two out of four. The HGN test is graded entirely on what the officer claims he saw in your eyes, with no recording and no number you can check. There is no objective score sheet you sign, no second opinion, and no way for you to know in the moment whether you are doing well. The officer decides, the officer records, and the officer testifies. A "battery" of three tests is really just three more chances for ordinary nerves, bad footing, and innocent movements to be logged as evidence against you. That is not a neutral measurement of sobriety. It is a system that converts the normal imperfections of a frightened person on the side of a road into "proof" of a crime, and it deserves to be treated with the skepticism it has earned.
Did a field sobriety test help convict you? Let's look at it.
If your case rests on a "failed" roadside test, it deserves a hard, informed challenge, because that evidence is far weaker than it sounds. Use the free case analysis on this page, or call me directly at (888) 271-6644. I answer my own phone, 24/7, and the first conversation is free.
From the DUI blog: It Was Raining the Night of Your DUI Arrest. Can Weather Affect Your Field Sobriety Tests?.