Pennsylvania HGN Test

The Horizontal Gaze Nystagmus or HGN is a field sobriety test that police officers often use to help determine if a person has been driving under the influence. The National Highway Traffic Safety Administration have standardized three field sobriety tests, one being the HGN. Of the three tests, the HGN is considered the most scientifically reliable, however this does not mean that if you failed the HGN you should plead guilty to DUI. We specialize in the defense of clients who failed their HGN test and we know the best possible defenses out there.

Alcohol is known to cause a nystagmus (involuntary jerking) in the eyes however some people suffer from a natural nystagmus as a result of brain damage, epilepsy or another type of neurological disorder. If you suffer from any of these, how can you be expected to “pass” the HGN?

If you have a glass eye or are wearing hard contacts, the officer should not have you perform the HGN test. The officer can ask you to remove your glasses in order to better see the movement of your eyes, however if you can’t see the stimulus you must be allowed to keep your glasses on during the test.

The police officer must also follow protocol when asking you to take the HGN test. The officer will have you follow a stimulus (usually a lighted pen) with your eyes, which should be held above eye level and at 12 to 15 inches away from your eyes to ensure they can focus on the object. Once you have stated that you can focus on the stimulus, the officer should give you instructions such as not to move your head, look straight in front of you and follow the stimulus with your eyes. The officer should have you perform the test while looking at a calm background and ensure that outside forces such as wind and dust do not affect your test.

The officer will be looking for a smooth pursuant of your eyes. They will also look for an involuntary jerking of your eyes when they are at maximum deviation.