How I Used Standardized Field Sobriety Tests to Defend a DUI – And Won

Standardized Field Sobriety Tests (SFSTs) are touted as the gold standard for detecting an impaired driver. When I do a jury selection, I always ask the question, “who here believes that if somebody can’t pass a field sobriety test, they must be drunk?” I almost always get a strong majority of people who raise their hands. Even defense attorneys fall for the propaganda. My friends over at Brighton Lewis offer courses on SFSTs and offer expert testimony that can be used to question or even completely negate the results of these tests. Even they admit that it can be difficult to convince attorneys to fight a case where the defendant “fails.” However, they, along with others in the know, understand that there are issues with SFSTs and many times they can be used to win a DUI case rather than as a conviction tool.

Before I give you some tips on how to successfully use the performance on SFSTs against the prosecution, let me first clarify what we’re talking about when we say SFSTs. They are a set of three tests that were developed by the National Highway Traffic Safety Administration (NHTSA) as a way to assisst officers at roadside in determining if a person may be impaired. There have been validation studies that test the accuracy of these tests, but they have only been validated for alcohol detection. They have not been validated to detect impairment as a result of drugs. SFSTs are not meant to be used to determine if a person is drunk; instead, they’re supposed to be used as an investigative tool to help decide if further investigation or testing would be warranted. This is not always how they’re used, though.

The three SFSTs validated by NHTSA are the Horizontal Gaze Nystagmus (HGN), Nine-Step Walk and Turn (WAT), and One-Leg Stand (OLS). The HGN is a test where the accused is required to follow some apparatus (pen, finger, etc.) with nothing but his eyes; the officer examines the eyes for nystagmus (involuntary jerking) at various points during the test. There are 6 possible clues; if an accused shows 4 or more, it is indicative of impairment. During the WAT, the accused walks nine heel-to-toe steps on an imaginary line, turns, and walks nine heel-to-toe steps back. There are 8 possible clues; 2 or more clues are indicative of impairment. The OLS requires the accused to stand on one leg while counting for thirty seconds; 2 or more clues indicate possible impairment. The information and clues gleaned from the tests are supposed to be used in conjunction with everything else the officer sees during his interaction with the accused to decide if the totality of the circumstances establish a belief that the driver may be impaired.The important thing to remember is that they’re an investigative tool and are not meant to be the only thing considered by the officer.

Although most people think the SFSTs can only be used to show that someone is drunk, I’m proof that they can be used to help exonerate a client as well. Last year, I had a case where the client was charged with DUI-General Impairment. This is the statute in PA that says that a person is guilty of DUI if he is substantially impaired by alcohol to the point that he cannot operate a motor vehicle safely. This is separate from the charge involving a person’s blood alcohol content (BAC is .08% or higher). The same techniques I employed can be used in cases involving BAC, as defendants are almost always charged under the General Impairment section as well. If there is a disconnect between the performance on the SFSTs and the BAC, the validity of the BAC number may be questionable. Also, as I discussed in a prior blog post, the results of the SFSTs can be used to challenge admissibility of evidence in a suppression hearing.

Tip number 1 – make sure there’s evidence of alcohol use. SFSTs are only validated for use when alcohol is suspected. If the police smell marijuana on your client and not alcohol, question the officer on why he would use an alcohol test on a suspected drug intoxication. If they only smell marijuana, or don’t smell anything at all and don’t have anything to suggest alcohol, that’s strike one  – there was nothing to indicate that alcohol was involved, and that is the only thing the SFSTs are validated to detect.

Also make sure that the tests are administered in the appropriate conditions and with the proper instruction. If there’s a dash cam video, WATCH IT! Make sure that what the officer says he saw is indeed what’s on that video. That’s your objective evidence. If anything on the video is different that the officer’s stated observations, you’ve got strike two – the objective video was very different from what the officers reported seeing.

Because I’m a Practitioner and Instructor of SFSTs, I know exactly how the tests were to be administered and what clues the officers should have seen. I first question the officer about what clues he saw. Once he is boxed into his answers, I showthe video to the jury/judge on the giant screen then go through the video second by second. I would ask questions such as “this is where you saw [insert clue here].” I would then say something like “we can agree that on this video, [the accused] isn’t [insert clue here].” If the clue clearly wasn’t seen on the video, the officer looks ridiculous and is forced to agree that it wasn’t on there. I do this over and over for each clue on each test. Going through the tests step-by-step while viewing the objective evidence is extremely effective. Strike 3- by the end, the officer loses all credibility.

Of course, you may be able to challenge other things. Maybe your client’s driving wasn’t bad. Maybe he was cooperative, coherent, and able to interact with the officers normally. Maybe he did almost everything we would expect from a sober driver. Maybe the officer was unreasonable or even combative with your client. But the ability to completely negate the performance on and testimony about the SFSTs is what really proves to the jury that this person was not substantially impaired to the point that he could not safely operate a car.

Of course, your job will be made easier if you have a dash cam video. However, if you don’t know how to correctly administer and score the test, the video is useless. The SFSTs come up in almost every DUI case; if you’re going to defend them, this knowledge is absolutely vital. If you don’t have a video, you can still challenge the tests. Some of the issues that regularly come up are: 1. The SFSTs are administered on someone who should be medically precluded from performing the test; 2. The accused is not properly instructed on how to perform the test; and 3. The officer doesn’t correctly score the test, either because he counts a clue that isn’t an enumerated clue by NHTSA, or because the officer scores clues more than once.

 Knowledge is power. Knowledge of the history of SFSTs, their purpose, and their administration can help you successfully challenge a DUI case.


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