The one leg stand is one of three FST’s most commonly used by police investigating a driver for DUI. Like the walk and turn test, it is a divided attention test. The first portion of the test consists of instructions from the police officer. The testing officer will instruct the suspect to stand feet together and arms at the side, while listening to all of the instructions.
The suspect will then be asked to perform the test, which is the second portion of the test. At this time, the suspect is to stand on one leg with the other foot six inches off of the ground, with the toe forward and parallel to the ground. The suspect may look at the raised foot and is instructed to count “one one-thousand…two one-thousand” until told to stop. In most cases, suspect is asked to perform the test for 30 seconds. According to the NHTSA, many individuals under the influence can perform the test for 25 seconds, but not the full 30 seconds. Thus, time is an important part of the test.
There are four clues that an officer will look for when conducting this test: 1) swaying; 2) using arms for balance; 3) hopping; and 4) putting the raised foot down. The NHTSA has determined that when two or more clues are present a suspect will have a BAC greater than .10% nearly 68% of the time.
Like all field sobriety tests, there are many factors that can cause a sober person to fail this test. For example, cold or poor weather, poor lighting, lights on the police car, and noise, wind, and lights from oncoming traffic can cause any person - whether sober or drunk - to fail this test. In addition, the test should be performed on a level surface. However, in many cases such a surface is unavailable. Moreover, even the type of shoes a suspect is wearing can affect the performance on any of the divided attention test. It is hard to imagine that a woman in high heels would be able to stand on one leg for 30 seconds.
Finally, it is important to note that all divided attention tests do not test for the presence of alcohol. These tests only look for “clues” of intoxication. In fact, there are many individuals who simply have poor balance due to weight, height, illness, fatigue, or other conditions and will fail these tests even when dead sober.
