Challenging Field Sobriety Tests in Tennessee
Challenging field sobriety tests starts somewhere most people do not expect: Tennessee's implied consent statute does not mention them at all. What they are, what NHTSA says counts as failing one, and where a challenge actually lands.
The Implied Consent Statute Covers Breath and Blood, Not These
Tennessee Code Annotated § 55-10-406 provides that the operator of a motor vehicle "is deemed to have given implied consent to breath tests, blood tests, or both tests." Breath and blood. The walk and turn, the one leg stand and the eye test are not named anywhere in the section, and no penalty in that statute attaches to declining them.
That is a narrower statement than most pages on this subject make, and it is narrower on purpose. Challenging field sobriety tests means separating what the statute does not require from what a prosecutor may later say about a refusal, and only the first of those has a clean answer.
So here is the honest version. Declining a field sobriety test does not trigger the license consequences that a breath or blood refusal does under § 55-10-406, which requires the officer to advise that refusal will result in suspension of the license by the court. It also does not prevent an arrest, and it does not make the case go away. Whether the fact that you declined can be raised at trial is a separate question this page does not answer, and anyone telling you flatly that it cannot is making a promise about a courtroom they have not been in yet.
Three Tests, Fifteen Clues, and a Decision Point of Two
The standardized battery comes from the National Highway Traffic Safety Administration and it is not subjective in the way people assume. Each test has a fixed number of validated clues, and on each one the decision point is two or more.
| Test | Validated clues | Decision point |
|---|---|---|
| Horizontal gaze nystagmus | 3 | 2 or more |
| Walk and turn | 8 | 2 or more |
| One leg stand | 4 | 2 or more |
On the eye test the three clues are lack of smooth pursuit, distinct and sustained nystagmus at maximum deviation, and onset of nystagmus prior to forty-five degrees. Two of those three is the decision point, which is a low bar and a specific one.
This matters because it turns a vague argument into a checkable one. An officer's report that says a driver "performed poorly" is not the standard. The standard is which numbered clues were observed, on which test, and whether the report and the footage agree about them.
The Tests Are Validated Only When They Are Given Correctly
NHTSA's own manual states that its procedures describe how the tests are to be administered "under ideal conditions," and that the battery has been scientifically validated only when conducted according to the established protocol. Administration that departs from the protocol is not the validated test.
That is the strongest ground available, and it is strong precisely because it is objective. It does not require arguing that an officer was biased or dishonest. It requires comparing what happened on the recording to what the manual says was supposed to happen. Instructions given, demonstration performed, the surface, the lighting, whether the driver was asked about physical limitations before being asked to stand on one leg.
The page this one replaces led with officer bias. That argument is hard to make, harder to prove, and unnecessary when a procedural deviation is visible on the body camera.
There Is No Field Sobriety Score in the DUI Statute
Section 55-10-401(1) requires that a substance impair the driver's ability to safely operate a motor vehicle "by depriving the driver of the clearness of mind and control of oneself that the driver would otherwise possess." Field sobriety tests appear nowhere in it. They are evidence offered toward that element, not the element itself.
Worth holding on to, because these cases can drift into a debate about whether somebody touched heel to toe. The question in front of the court is the statutory one. Six clues on a walk and turn is a fact a jury may consider on the way to answering it, and so is everything else about the stop.
The same logic runs the other way. A clean performance on all three tests does not end a case where a number exists, because § 55-10-401(2) supplies a separate route at 0.08% alcohol concentration. Where there is no number, which is every drug case, the tests carry much more weight. Our prescription medication DUI post covers that situation, and the implied consent page covers the breath and blood side.
What Else Produces the Same Clues
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The surface and the conditions
The manual describes ideal conditions. A sloped shoulder, gravel, rain, traffic passing three feet away and headlights in the eyes are not ideal conditions, and each of them is documented on the recording rather than argued from memory.
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Physical and medical baseline
Inner ear problems, back and knee injuries, neurological conditions, age and weight all affect balance tests. The question worth asking is whether the officer asked about any of it before the test, because the manual contemplates that inquiry and the footage shows whether it happened.
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Footwear and what the driver was wearing
Heel to toe on a straight line in boots, dress shoes or heels is a different task than in trainers, and it is another thing the video answers without anyone having to remember it.
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The stop itself
Before any of this, there has to have been a lawful basis for the stop and for the detention that followed. If that is in question, the tests and everything after them are downstream of it.
None of that predicts an outcome. It describes what is actually examinable in a case built on these tests, which is a different and more useful thing than a list of arguments.
Challenging Field Sobriety Tests FAQ
Do I have to take field sobriety tests in Tennessee?
Section 55-10-406 deems the operator to have consented to breath tests, blood tests, or both. Field sobriety tests are not named in it and no penalty in that statute attaches to declining them. That is not the same as saying a refusal can never be mentioned in court, which is a separate question.
Is a urine test part of implied consent?
Not under § 55-10-406, which refers to breath tests, blood tests, or both tests. Descriptions of Tennessee implied consent that include urine are describing something the section does not say.
How many clues does it take to fail?
Under the NHTSA battery the decision point is two or more clues on each test. Horizontal gaze nystagmus has three validated clues, walk and turn has eight, and one leg stand has four.
What is the strongest way to challenge these tests?
Usually administration. NHTSA validates the battery only when it is conducted according to the established protocol and describes its procedures as applying under ideal conditions. Comparing the recording to the protocol is objective in a way that arguing about an officer's judgment is not.
Can I be convicted on field sobriety tests alone?
The statute does not mention them. Section 55-10-401(1) asks whether the driver was impaired by depriving the driver of the clearness of mind and control of oneself the driver would otherwise possess. Field sobriety tests are evidence offered toward that question rather than a separate test the statute sets.
Does a medical condition matter?
Balance and coordination tests are affected by inner ear conditions, injuries, neurological conditions, age and weight. Whether the officer asked about physical limitations before administering the test is visible on the recording and is usually where that issue gets examined.
Get the Footage Before Anything Else
Austin Tomlinson defends DUI cases in Davidson County and across Middle Tennessee, and takes every case himself. Body and dash camera recordings are kept on a retention schedule and then overwritten, so a preservation request early is worth more than any argument made late.