Horizontal Gaze Nystagmus (HGN) test is a field sobriety test that is used in Jacksonville DUI cases. The Jacksonville DUI officer uses a pen light to track the DUI suspect’s eyes. The DUI officer looks for three clues on each eye.
- Smooth Pursuit: The Jacksonville DUI officer moves the pen light smoothly and slowly from the center all the way out to his right side, checking the Jacksonville DUI suspect’s left eye. Then, the DUI officer moves it his left side, checking the DUI suspect’s right eye. The Jacksonville DUI officer returns the pen light back to the center of the driver’s face. This takes approximately two seconds. The Jacksonville DUI officer must do this portion of the test at least twice. He is looking for the eye to “lack smooth pursuit” and make a jerking motion.
- Nystagmus at Maximum Deviation: The Jacksonville DUI officer holds the pen light as far to the right as possible, checking the Jacksonville DUI suspect’s right eye. He is looking for a distinct and sustained jerking of the eye. The Jacksonville DUI officer does the same to the right eye. He must check each eye at least twice.
- Nystagmus Prior to 45 Degrees: The Jacksonville DUI officer uses the pen light to notice when the eye begins jerking. Usually, the officer is looking for the Jacksonville DUI suspect’s eyes to begin jerking before the pen light reaches a 45 degree angle. The 45 degree angle occurs approximately at the Jacksonville DUI suspect’s shoulders. This is also performed twice on each eye.
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