The Nystagmus Test

The Nystagmus Test

If you are currently involved in a DUI case, you may have a vague understanding of the tests that officers use to determine the percentage of BAC (Blood Alcohol Content). An Orange County DUI lawyer will get a lot of questions from his or her clients about these tests and how they work. The Nystagmus test is one of the common standardized tests—one with which your lawyer should be very familiar.

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This test requires the subject to follow a focal object with their eyes. (“Nystagmus” means eye movement.) The police pay particular attention to the person’s ability to move their eyes smoothly without telltale shifts. The test is administered with the suspect’s glasses off. The suspect must stand with feet together and hands at their side, keeping their head still. The subject must follow an object with their eyes only, without his or her head turning. The focal item is held about a foot from the nose, just above eye level.

What They Watch For

The officer is looking at how well the eyes track the object, as well as equal pupil size. To determine whether the eyes track smoothly an officer starts with the subject’s left eye and moves the stimulus item so it takes about two seconds to move the eye to each side.

One of the assessments, maximum deviation, evaluates possible shifting when the eyes are gazed way off to one side, as far as possible, for several seconds. Other specific measures include “nystagmus prior to a 45 degree angle,” and “vertical nystagmus” in which the focal object is moved up and down instead of side to side. Here again the test looks for the smooth tracking of the eyes. The officer should repeat the test in a specific sequence to confirm findings and come up with a total score for reporting purposes. An experienced Orange County DUI lawyer will know about the scientific method behind this  test.

How accurate is this widely used, standardized examination? What are the details of how the test should be given? An Orange County DUI lawyer is knowledgeable of all the facts and will advise you on how they might impact your case. Call the Law Office of Mike Coffey Attorney at Law& the Law Office of Mike Coffey Attorney at Lawtoday at (800) 706-7888.