WHAT IS HGN?
HGN stands for Horizontal Gaze Nystagmus. ” Nystagmus is defined as “an involuntary rapid movement of the eyeball, which may be horizontal, vertical, rotatory, or mixed.” Alcohol slows down the eyes’ ability to rapidly track objects and causes to eyes to oscillate, or “jerk”, before they normally would in a sober person. Alcohol stimulates the nerve endings, making nystagmus more pronounced in intoxicated persons. As a person’s blood alcohol concentration increases, the eyes will “jerk” sooner as they move to the side. The HGN test claims to gauge intoxication by measuring the involuntary oscillation of the eyes.” (H.G.N. by Laine Means, http://forensic-evidence.com/site/Biol_Evid/HGN.html) The National Highway Traffic Safety Administration (“NHTSA”) tells law enforcement that if the officer administers the HGN according to the standardized procedures established by NHTSA, then the officer can correctly identify persons who are likely to test over 0.10 of a gram per 210 liters of exhal
