When you are pulled over for suspicion of a DUI, the officer will conduct a test called “horizontal gaze nystagmus” or HGN for short. This is the test where an officer will ask you to follow either their finger or a pen to see if the eyes involuntarily jerk or twitch as your eyes move laterally.

The test must be done correctly. The officer must place the stimulus (usually a pen or their finger) 12 to 15 inches away from your nose and slightly above eye level. Then the officer must move the stimulus in a stage consisting of 14 passes. The first stage of passes has the officer moving the stimulus from left to right to center for at least two seconds to check or equal tracking of the pupils.

The second stage has the officer place the stimulus from the center position to your left and back to the center. They will repeat this for the right eye. The stimulus should be moved at a speed that takes at least two seconds from the center position to the side position.

The third stage of passes is designed to determine whether the person has distinct nystagmus at the point in which your eye is fully moved to one side and cannot move any further. The stimulus moves from center to the side taking at least two seconds, holding at the side for at least four seconds, and then moved back to the center in at least two seconds.

The final stage is a set of four passes designed to determine if the onset nystagmus occurs before your eye moves to a 45-degree deviation. It must take at least four seconds to move the stimulus from your center to a spot around your shoulder. The stimulus must be held long enough to confirm the onset nystagmus. Each of the passes in this phase must take at least eight seconds, with a three second count out, a two second count hold, and a three second count back.

 

It is vital to note that the entirety of the HGN test must take AT LEAST 82 seconds- usually around 90 seconds. If the officer is well under that time, then they employed the test incorrectly and the HGN test can be excluded from any evidence that could indicate potential impairment. The stimulus must also remain in the 12 to 15 inch range from your nose and its path cannot loop or curve. If it does, then the officer did not administer the test properly. If you’re pulled over for a DUI, make sure you know the process for HGN evaluation and call our office today.