DUI Field Sobriety Tests

Most of us have watched on TV, or even seen in person, vehicles stopped by the police, with the driver being subjected to questions and being asked to perform certain acts, such as walking a straight line. What is usually happening is that the officers are administering what are known as field sobriety tests (FST’s).

What are FST’s?

As a technical matter, a field sobriety test can be anything from standing on one foot to reciting something (the alphabet, for example), to staring into a light. A request that you perform any act that purports to test whether or not you are sober or intoxicated falls within the general heading. But not all field sobriety tests are created equal.

A number of years ago the United States National Highway Traffic Safety Administration (NHTSA) examined certain studies involving driving under the influence. The studies, or at least some of them, came to certain conclusions regarding a driver’s performance on specific tests, and the likelihood that failure indicated impairment. The NHTSA endorsed three tests for this purpose, and these have become known as Standard Field Sobriety Tests (SFST’s):

  • Horizontal Gaze Nystagmus (HGN). Nystagmus is an involuntary movement of our eye that occurs when we look to the side. The theory behind the HGN test is that the angle of the eye at which nystagmus occurs changes when a person is intoxicated. By measuring the angle as the eye follows a penlight, so the theory goes, the officer can tell if you are drunk. Specifically, the study that the NHTSA relies on says that the HGN test can predict with 88% accuracy if you have a blood alcohol content of 0.08 or greater.
  • Walk and Turn. This test consists of a request that you walk heel to toe taking a certain number of steps, then turn and repeat the steps in the opposite direction. This is known as a divided attention test, because while you’re walking and turning, the officer will be giving you instructions. There are numerous ways to “fail” the test, including losing your balance, using your arms to control your balance, swaying, stopping, even beginning to walk before the officer finishes the instructions. A fifteen year old study claims that if you exhibit two instances of “failure” there is a 79% chance you are legally intoxicated.
  • One Leg Stand. This is another divided attention test, the essence of which, as the name suggests, is standing on one foot. At the same time, you are asked to count aloud by thousands until directed to put your foot down. The test lasts for 30 seconds. Indications of failure are similar to those involved in the walk and turn test. The NHTSA says that if there are four instances of failure, you have an 83% chance of being intoxicated.

There are other tests that have been and continue to be employed by law enforcement officers, and many of them are anything but standard. A simple example would be asking a driver to count backwards by three’s, or reciting a portion of the alphabet starting with a letter in the middle of the alphabet.

How Can I Defend a Claim that I Failed an FST?

The results of SFST’s and non-standard FST’s can be challenged, and in many cases they can be challenged successfully. Initially, remember that just because a police officer administered a “test” – and even though the NHTSA says that they think the test is a valid measure of intoxication – the fact that you have allegedly failed that test does not mean that you were intoxicated, and it does not mean that you are guilty of DUI. It is merely a piece of information that may or may not be admitted into evidence. And even if it is admitted, neither a judge nor a jury is bound to give it significant weight, or any weight at all for that matter.

Here are some of the ways in which an experienced Phoenix DUI attorney can challenge the results of FST’s:

  • Qualifications of the officer. Many officers consider themselves Drug Recognition Experts, but only a small percentage of them are actually certified as such. In addition, the officer may not have been properly trained to administer the FST’s they seek to use against you.
  • FST Results are always subjective. No matter which test is administered, there are no “black and white” results that lead to a definitive conclusion concerning intoxication. What may look like loss of balance to one person may not to another. Coming to concrete conclusions on an HGN test administered at night with headlights passing cries out to be challenged.
  • FST’s measure coordination, not intoxication. Any test, such as the walk and turn or the one leg stand, which looks for errors in balance and the like, measures coordination. The law enforcement argument is that most intoxicated people are uncoordinated. Therefore, the argument continues, if you are uncoordinated, then you are intoxicated. The reasoning is flawed, and the conclusion is nonsense. Moreover, lack of coordination, inability to pass the HGN test, red eyes, and other alleged indications of intoxication can be caused by many things, including specific physical and medical conditions, which have nothing to do with the consumption of alcohol or drugs.

Defense of your Phoenix DUI

Properly defending a DUI requires not only legal knowledge, but also familiarity with a host of areas that may be the subject of inquiry in your case. At the Law Office of Bret A. Royle, we specialize in representing clients charged with drunk and drugged driving. Our expertise in DUI cases is second to none, and we combine our experience with an absolute dedication to each of our clients. Call us today for a free, confidential consultation.

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