What is the Horizontal Gaze Nystagmus Test?

Horizontal gaze nystagmus (HGN) is an involuntary horizontal jerking or bouncing of the eyeball that occurs when one’s eye gazes to the side. Alcohol consumption impairs your brain’s ability to control your eye movements, which makes the HGN appear. The more alcohol you have consumed, the more pronounced the jerking or bouncing of the eyeball becomes.

The HGN test is one of three standard field sobriety tests used by law enforcement officers when they suspect individuals of driving while intoxicated. The other two standard field sobriety tests are the walk-and-turn test and the one-leg-stand test. These three tests constitute the standard battery of tests to detect the presence of alcohol or certain other drugs that may impair a person’s ability to drive.

To properly administer the HGN test, a police officer holds an object, such as a pen or penlight, approximately 12 to 15 inches from the subject’s face and slightly higher than eye level. The officer then instructs the individual to follow the object with his or her eyes only, but without moving his or her head. The officer quickly moves the object across the individual’s field of vision to gauge whether his or her eyes are able to simultaneously track the object.

Regardless of the scientific evidence that proves the effectiveness of the HGN test, the results of this test are typically not the crucial pieces of evidence that results in a DWI charge or conviction. Rather, police officers often use the HGN test and other field sobriety tests to establish probable cause to administer a breath test or arrest an individual for DWI. The Missouri DWI & Criminal Law Center has the reputation and skills that you want and need when defending yourself against criminal charges related to DWI, traffic violations, and other matters. Our goal is to assist you in building the strongest defense available in your case. We also can assist you with the expungement process, which can help improve your future by sealing your previous criminal records. Do not hesitate to contact Benjamin Law Firm, LLC, at (816) 322-8008 or fill out the online information form located here.

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