Most people have probably heard about, seen or experienced the variety of tests police give to suspected drunk drivers to try to determine if individuals are impaired. These tests are collectively referred to as standard field sobriety tests (SFST). Many people may be surprised to learn that they may refuse an officer’s request to take them, and generally it is in a person’s best interests to decline to have them administered.
The National Highway Traffic Safety Administration (NHTSA) developed these tests and assists in training officers in how to administer them. There are three types of tests:
- Horizontal Gaze Nystagmus (HGN): HGN refers to the involuntary jerking of the eye which happens naturally when a person gazes to the side, but may be more exaggerated when a person is impaired. To administer this test an officer observes a suspect’s eyes as he or she follows an object like a pen.
- Walk-and-Turn (WAT): As the name indicates, this test involves the suspect taking nine, heel-to-toe steps, and then turning on one foot, and continuing in the opposite direction while listening to instructions. The officer looks for indications that the suspect has difficulty having their attention divided between physical and mental exercises.
- One-Leg Stand (OLS): In the OLS a suspect is asked to stand while holding one foot off the ground and counting aloud. Like the WAT test, the officer is attempting to see if the suspect has difficulty dividing his or her attention between two types of tasks. An officer may look for indicators like swaying, or using arms or hopping to maintain balance.
All of these tests are subjective, and an experienced DUI attorney can challenge an officer’s belief that a person’s performance of SFSTs indicated impairment. Research has shown that the tests are not 100 percent accurate. A study cited by NHTSA itself shows that the tests are incorrect 12 to 21 percent of the time.
Source: NHTSA, Standard Field Sobriety Testing
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