Horizontal Gaze Nystagmus Test

If you have ever been instructed to perform a field sobriety test under the suspicion that you were driving under the influence, you may have been asked to perform the horizontal gaze nystagmus. This roadside test is designed to assess a driver’s vision and/or cognitive alertness. To administer this test, the suspected drunk driver must be instructed to look straight ahead, keeping their head still, while they follow an object—like a pen or a finger—as it moves horizontally, with only the motion of their eyes. There are three signs of intoxication that an officer looks for when administering this test, those being lack of smooth pursuit, distinct jerkiness, and angle of onset.

Three Signs of Intoxication

• The first, lack of smooth pursuit, means that the DUI suspect is unable to track the object smoothly with their eyes. This might mean that the individual turns their head slightly to follow the movement of the object or that their eyes bounce or jerk as they move side to side.
• The second, distinct jerkiness means that an officer will ask the suspect to track the object as far to the side as their eye allows and to hold their gaze there for two to three seconds. The officer will then observe for any distinct jerkiness.
• Finally, the angle of onset technique may be used to observe any jerkiness, as well. An officer will slowly move the object at a 45-degree diagonal to assess sobriety.

Although thisfield sobriety test is considered to be the most reliable of the three, it is still believed to be only 77% accurate. The officer must be trained to properly administer this test and to observe and score it correctly. Otherwise, the results could prove to be invalid. There are several factors that could contribute to negative scoring when performing this test, so do not think that just because you have failed a field sobriety test that you will automatically be convicted of a DUI.