Virginia Horizontal Gaze Nystagmus Test: NTHSA field sobriety test

Virginia DUI Defense: Virginia Horizontal Gaze Nystagmus Test

One of the National Highway Safety Administration’s standardized field sobriety tests is the Horizontal Gaze Nystagmus. When Virginia police ask you to perform this field sobriety test, they will be looking for any involuntary jerking of the eyes, which is often caused from alcohol consumption.

Nystagmus can occur naturally when your eyes look to the sides at high peripheral angles. However, when a person is impaired by alcohol, nystagmus can occur at lesser angles and appear more exaggerated. And someone who is impaired by alcohol may also have more difficulty smoothly following an object that is moving.

During the HGN field sobriety test, the officer will have you follow an object such as a lighted pen or a flashlight horizontally with your eyes. In each eye, the officer is looking for three clues: a lack of smooth pursuit when following the object; any jerking occurring when the eye is looking at the furthest degree; jerking that starts within 45 degrees of the center. If the officer notices four of these clues occurring between the two eyes, it is likely that your blood alcohol content is at least .10 and is over Virginia’s limit of .08. The HGN is also a way for officers to test for any depressants, barbiturates, or the consumption of any seizure medications.

If you have failed your HGN field sobriety test, it’s important to know that this doesn’t automatically result in proof that you were drinking and driving. In fact, many people suffer from a natural nystagmus in their eyes. Also, there are errors that the officer could have made to enable nystagmus such as moving the object too quickly, making it come too close to your eyes, or by not allowing you enough time to follow it during the test.

At Boone Beale, we don’t accept failure of the HGN test. We will get to the bottom of your case, cross–examine the officer if necessary, and find out if mistakes were made on the part of law enforcement. Remember, failing your HGN test does not mean a DUI conviction.