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What is a nystagmus?

If you have ever been stopped by an officer while driving and eventually asked by the officer if you have consumed alcohol, you might find yourself questioned about your sobriety and fitness to drive. One of the things routinely done during a traffic stop that may turn into an investigation for suspected drunk driving is to have a driver perform certain tests or be evaluated for certain factors. The results of these things may then be used to support placing that driver under arrest.

As explained by, one of the tests used is called the horizontal gaze nystagmus test. A nystagmus is a type of jerking motion made by the eye that occurs naturally. It is said that after a person has been drinking, the jerking may be more pronounced. In order to check for the level of motion, an officer will ask a driver to fix their gaze on a certain item that is held about a foot away from the driver’s face.

Without any movement of the head, the driver is then supposed to follow the movement of the item from side to side as manipulated by the officer holding that item. During this eye tracking, the officer evaluates the nystagmus in a horizontal fashion. Certain neurological conditions are just some things that may contribute to inaccurate results with this test.

This information is not intended to provide legal advice but is instead meant to give Virginia residents some background about one of the three field sobriety tests used by law enforcement during a drunk driving investigation.