Horizontal Gaze Nystagmus is characterized by what behavior of the eyes?

Horizontal Gaze Nystagmus is characterized by the involuntary jerking of the eyes as they move to the side. This occurs when a person is asked to follow an object with their eyes, such as a finger or pen, and the eyes exhibit a jerking motion rather than a smooth pursuit. This condition is often associated with impairment caused by alcohol or certain drugs, making it a key indicator during field sobriety testing.

The behavior of the eyes during Horizontal Gaze Nystagmus is crucial for law enforcement officers to observe because it provides insight into a suspect's level of impairment. Observing this involuntary jerking can help in assessing whether an individual is under the influence, as properly functioning eyes typically move smoothly without any jerking.

Understanding this specific response when the eyes are tested assists law enforcement in making more informed decisions during sobriety evaluations.