For how long must the HGN test be administered at a minimum?

The Horizontal Gaze Nystagmus (HGN) test is a field sobriety test used by law enforcement to assess a driver's level of intoxication, primarily for alcohol use. The test specifically measures involuntary eye movement (nystagmus) as the eyes follow a moving object, usually a pen or flashlight.

Administering the HGN test for a minimum of 4 seconds is critical because it allows for accurate observation of the eye's movement for signs of impairment. If the test is conducted for less than this duration, the officer may not fully observe the nystagmus, leading to an incorrect assessment of the driver's sobriety. By having a standardized duration of at least 4 seconds, it ensures that the officer collects sufficient data to make a reliable judgment about any potential alcohol influence. This methodical approach is part of the standardized procedure, which promotes consistent and fair testing across different situations and officers.

In contrast, administering the test for shorter durations could compromise the integrity of the results, as the signs of impairment may not be clearly visible to the observer, thereby affecting the outcome of the test results. The 4-second minimum, therefore, plays an essential role in the effectiveness of the HGN as a reliable indicator of impairment