Horizontal Gaze Nystagmus (HGN)

This is the first test the officers in a Ventura County DUI usually have you perform. The HGN test involves the officer holding his pen, finger, or flashlight about a foot from your face and moving it from side to side while checking your eyes as you attempt to follow it. What the officer is looking for is called nystagmus, which is the involuntary jerking or bouncing of the eyes as it attempts to track a horizontally moving object smoothly. The person performing the HGN test cannot feel the bouncing of the eyes, and can’t do anything to prevent – nystagmus because it is totally and completely involuntary. Among the three standardized FSTs, the HGN test is probably the most accurate in showing the presence of alcohol, as HGN is present when someone has alcohol in their system. However, HGN can be present at very low alcohol level, so the fact that HGN might be observed by the officer does not in and of itself show that someone is under the influence of alcohol.

Occasionally the officer will perform the HGN test on you while you are still sitting in the car. However, the HGN test is only standardized and validated if the officer is eye to eye with you, which is why the test is supposed to be performed with you standing up. During the standardized and validated HGN test, the officer should hold an object, such as his/her finger, a pen, or a flashlight (with the light NOT pointing in your eyes) about 12-14 inches from your face. The officer must tell you to keep your head still, and track the object as it moves from side to side by moving your eyes only. The object should start in the middle, and move slowly out to about your shoulders, where the officer should hold the object still for about two to four seconds, and then the object should be moved to the other side and held still again. As this process is repeated, the officer should be looking at your eyes for certain cues. On the HGN test, there are 3 possible cues each eye (for a total of 6), and 4 or more may indicate impairment. The cues on the HGN test are lack of smooth pursuit, onset of nystagmus prior to 45 degrees, and nystagmus at maximum deviation. Whether or not the officer notes your eyes as being red and watery, bloodshot, or anything else beyond those 3 cues is not related to the HGN test. An experienced Ventura County DUI attorney who is P.O.S.T. certified in Field Sobriety Tests understands how the HGN test is supposed to be administered, and knows how to use your performance on the HGN to your best possible advantage. Contact The Law Offices of David Lehr Law for a P.O.S.T certified Ventura County DUI attorney .