Police officers follow procedures set forth in the NHTSA/IACP curriculum when they administer the Standardized Field Sobriety Tests (SFSTs) to suspected alcohol-impaired drivers. The SFSTs include Horizontal Gaze Nystagmus (HGN) test, Walk-and-Turn (WAT) test, and One-Leg Stand (OLS) test. Courts generally accept testimony about WAT and OLS, but may not admit testimony about HGN. It has been argued that variations from standard procedures in HGN administration affect its validity and should render testimony about it inadmissible. Three experiments examined the effects of procedural variations in administration of the HGN test. Variations in stimulus speed and elevation, and distance of the stimulus from the suspect's face were examined in a laboratory experiment. A second experiment conducted in training workshops varied the participants' positions (standing, sitting, lying down). The third experiment examined HGN in participants who have functional vision in only one eye. The data demonstrate the validity of the HGN test with both standard and varied testing procedures. The variations did not alter the occurrence of, or the observations of, HGN.
United States. National Highway Traffic Safety Administration
1990-11-01
Abstract:
Sobriety checkpoints have been a valuable tool for law enforcement's continuing fight to remove impaired drivers from the road. The purpose of the che...
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United States Department of Transportation
[PDF-3.66 MB]
