What is the minimum duration to observe eye jerk at maximum deviation?

The minimum duration to observe eye jerk at maximum deviation is four seconds because this time frame allows for sufficient observation to determine the presence and degree of nystagmus, which is an involuntary eye movement that can indicate impairment. During a field sobriety test, officers look for this specific eye movement as part of the Horizontal Gaze Nystagmus (HGN) test. By observing the eyes for four seconds at maximum deviation, an officer can gather valuable information on whether the subject may have consumed alcohol or drugs to a level that impairs their ability to drive.

This duration is critical because it ensures that the observer can accurately assess the eye's reaction and make a reliable judgment regarding potential intoxication. Shorter observation times may not provide sufficient evidence to accurately identify the presence of nystagmus, which could lead to incorrect conclusions about a person's level of impairment.