Field Sobriety Tests
Unlike blood alcohol content or breath tests, field sobriety tests are voluntary in most states. That means that in most states, you can simply decline to take them. For most people, though, the concern about field sobriety tests arises later, when you’ve been charged with a DUI. At that point, the key is to determine whether or not the field sobriety tests as administered are valid evidence.
The National Highway Transportation Safety Administration (NHTSA) created a standardized model for field sobriety testing in 1981. The SFST uses three tests in combination, and the NHTSA recommends that all law enforcement agencies use this standardized program and the associated training.
The simple existence of this standardized testing system—a system that NHTSA has deemed the most reliable of the available field tests--can create a point of attack for a DUI attorney in an area where the standardized tests aren’t used.
Even where the standardized test is used, though, there are some chinks in the armor. The SFST was designed to help officers measure the appropriateness of making an arrest in a DUI case, not as evidence to prove that a driver was intoxicated.
According to 1998 data from the NHTSA itself, the combination of three tests used together is only accurate in 91% of cases. That means that the officer is wrong in 9 out of every 100 assessments—and those were the officers who volunteered their DUI arrest records!
And, of course, not all officers who use the SFST as a preliminary DUI assessment have been properly trained to administer and interpret it. Accurate administration of the three tests according to NHTSA procedures requires that an officer follow strict guidelines. All three tests must be administered, and must be administered under certain conditions.
The One-Leg-Stand Test
The NHTSA procedures for administering the One-Leg-Stand Test require that the officer:
- Instruct the suspect to stand with his feet together and arms down at his sides, and demonstrate.
- Tell the suspect not to begin until he’s told.
- Ask the suspect whether he understands the instructions.
- Explain that when the suspect is told to begin, he must raise one leg approximately six inches off the ground with the toe pointed out and hold the position while counting out loud for thirty seconds saying, “One thousand and one, one thousand and two…” (and demonstrate the position).
- Remind suspect that he must keep his arms at his sides and keep watching his raised foot.
- Ask the suspect whether he understands and wait for a response.
- Tell suspect to begin the test.
- Observe the test from three feet away and remain as motionless as possible.
- If the suspect puts his foot down, tell him to pick it up again and resume counting from where he left off.
- If the suspect counts too slowly, end the test after thirty seconds; if he counts very quickly, instruct him to continue until told to stop.
The Horizontal Gaze Nystagmus (HGN) Test
The Horizontal Gaze Nystagmus test, in many states, provides the most fertile ground for challenge among the field sobriety tests. That’s because some DUI courts have ruled that it’s a scientific test, and therefore requires the state to establish that the officer is qualified to interpret the test and testify to the results. Testing procedures require that the officer:
- Instruct the suspect that he’s going to check his eyes, that he must keep his head still and follow the object only with his eyes, and that he must focus on the object until told to stop.
- Hold the stimulus 12-15 inches from the suspect’s nose and slightly above eye level.
- Move the stimulus smoothly across the suspect’s entire field of vision.
- Check to see if the eyes are tracking together.
- Check to see whether both pupils are the same size.
- Start with the left eye and move the stimulus smoothly to the right so that it takes about two seconds to bring the suspect’s eye as far to the side as it can go. Repeat from right to left.
- Check at least twice for each of the three clues in each eye: lack of smooth pursuit; distinct nystagmus when eye is directed to the outside of field of vision (where no white is showing at the side of the eye) for four seconds; onset of nystagmus before the eye has moved 45 degrees.
The Walk and Turn (WAT) Test
In addition to the requirements for officer administration, the Walk and Turn Test requires certain conditions to be administered properly. For instance, level ground is required, along with a hard, dry, non-slippery surface. Even with optimal conditions, NHTSA indicates that WAT may not be valid for the elderly, people with leg injuries, or people with inner ear problems. That warning may not keep officers from administering the test to people who fall within those categories in the field, but they can provide a powerful weapon against the results of the tests in a DUI case.
The officer administering the test must:
- Instruct the suspect to place his left foot on the line and his right foot heel-to-toe in front of it, and demonstrate.
- Confirm that the suspect understands that this position must be maintained while the instructions are relayed.
- If the suspect breaks position during the instructions, stop the instructions until the suspect is back in position.
- Tell the suspect not to begin until he is instructed.
- Tell the suspect that he will be required to take nine heel-to-toe steps down the line, turn around, and take nine steps back down the line.
- Demonstrate two or three heel-to-toe steps.
- Instruct the suspect to keep both arms at his sides, watch his feet, count the steps out loud, and not to stop walking until the test is complete.
- Ask the suspect whether he understands the directions.
- If the suspect indicates that he does not understand the instructions, repeat the part that he does not understand, but not the entire instructions.
- Tell the suspect to begin, and that he should count his first step from the heel-to-toe position as one.
- If the suspect staggers, steps off the line, stops or stumbles, have him resume from the point of interruption.
When field sobriety tests are administered as they were intended, simply as a tool to help an officer decide whether further action is required, they won’t often have a significant impact on a case. However, field sobriety tests can become a critical piece of evidence in a DUI case where there has been a blood test or breath test refusal or the breath / blood test has been found to be unreliable and suppressed. In those cases, the stringent guidelines set forth for test administration can often provide the crack your attorney needs to weaken or even exclude the field sobriety test results. While some DUI courts may admit field sobriety tests that were administered imperfectly and let the defense attorney argue that they were inaccurate, some have gone so far as to say that tests not administered according to the NHTSA training are inherently unreliable and exclude them as evidence altogether.