Types of Tests:
- Horizontal Gaze Nystagmus
- Walk and Turn
- One-leg Stand
The one-leg stand is one of the three standardized field sobriety tests established by the National Highway Traffic and Safety Administration. When an officer properly administers the one-leg stand test, research has shown the test to be 65% accurate in determining if a driver has a blood alcohol content level above .10%.
The test is fairly simple, but an officer must make sure that the subject understands what is required of him or her. The standard procedure for administering the one-leg stand requires an officer both to explain and demonstrate the test. First, the officer demonstrates and explains the proper standing position to the subject. For this, the subject is instructed to stand with feet together and arms down at the sides.
Next, the officer instructs the subject to continue to keep his or her hands at the sides and raise either leg roughly six inches above the ground. In this position, the subject is asked to count upwards starting at 1,000. The officer demonstrates and explains that the correct counting method goes “one thousand and one, one thousand and two, one thousand and three,” and so on until 1,030.
Before the subject begins the test, the officer is required to ask again if there are any questions or doubts as what is asked of him or her.
While the subject performs the test, the officer looks for four signs that indicate the person may be intoxicated:
- Swaying while balancing – Although it is natural for humans to sway slightly in order to keep their balance, the officer is trained to look for marked swaying, such as a back-and-forth movement.
- Using the arms to keep balance – If the subject raises his or her arms more than six inches from the side of the body, then this is a sign that he or she is having significant difficulties maintaining balance.
- Hopping on the anchor foot in order to maintain balance – It is permissible for a person to move the anchor back and forth slightly, but raising it off the ground is now allowed.
- Resting the raised foot on the ground three or more times during the required thirty seconds – The person is considered unable to complete the test.
The one-leg stand test must be performed on dry, hard, level land. If a person is wearing heels above two inches, he or she is allowed to remove them. The elderly, people with back, leg, or middle ear problems, and overweight people often have difficulty with this test when sober. It is, therefore, difficult to determine for certain if they have been drinking. In these instances, officers usually substantiate the one-leg stand test with the horizontal gaze nystagmus field test or a breathalyzer test.