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Horizontal Gaze Nystagmus (HGN) Test

The Horizontal Gaze Nystagmus test, also known as HGN test, is an eye examination some local police officers and all California Highway Patrol Officers have been trained to administer. The officer will hold a a pen or finger 12 to 15 inches from the driver's nose.

The officer will tell the driver to keep their head still and follow the pen with their eyes. The officer will then move the pen from side-to-side while watching the driver's eyes. If the driver's eyes fail to smoothly track the stimulus, nystagmus or jerking at the extreme outer edge of vision, and an onset of nystagmus prior to forty-five (45) degrees, the officer will interpret this as a sign that the person is impaired by alcohol.

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Attorney Robert Tayac Puts a Long, Decorated Career to Work for You
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