What type of test is the Horizontal Gaze Nystagmus considered within Law Enforcement?

The Horizontal Gaze Nystagmus (HGN) test is categorized as a standardized test in law enforcement. This classification arises because the HGN test is part of the Standardized Field Sobriety Tests (SFST) protocol, which has been scientifically validated and is designed to assist law enforcement officers in assessing a suspect's level of impairment due to alcohol or drugs.

Standardized tests like the HGN are administered in a uniform manner, following specific procedures that are widely recognized and accepted in both law enforcement and the judicial system. The test is based on observable physiological responses that are consistent across different individuals, making it a reliable tool when detecting impairment. Officers are trained to conduct the test systematically, ensuring consistency in how it is performed and evaluated, which is crucial for its reliability as evidence in court.

In contrast to subjective tests, which rely more on an officer’s personal judgment and interpretation, the standardized nature of the HGN test helps provide an objective basis for assessing a suspect's impairment. While it could partially be considered a field test as it is conducted during traffic stops or roadside assessments, the primary emphasis is on its standardized methods and scientific backing that firmly categorize it within the standardized testing framework.