What is the maximum number of clues for Horizontal Gaze Nystagmus (HGN) in one eye?

The maximum number of clues for Horizontal Gaze Nystagmus (HGN) that can be observed in one eye is indeed three. HGN is a field sobriety test that is often used by law enforcement officers to assess whether a driver may be under the influence of alcohol or drugs. The test involves observing the subject's eyes as they follow a stimulus, typically a pen or a finger, and officers are trained to look for specific signs or "clues" of impairment.

In terms of the HGN test, the three clues that can be noted in one eye include:

1. The inability to smoothly pursue a moving object.

2. A distinct and sustained nystagmus at maximum deviation.

3. A noticeable onset of nystagmus prior to 45 degrees.

Each of these clues indicates that the person may be experiencing impairment, as they suggest a lack of normal function in tracking movement. While it's essential to be aware of all aspects of HGN, it is this specific scoring of three clues per eye that helps officers determine the likelihood of impairment. Understanding these components is critical for accurately administering the test and interpreting the results.