Criminal Defense in Orange County

Understanding the Horizontal Gaze Nystagmus Test

The horizontal gaze nystagmus test is one of three field sobriety tests standardized by the National Highway Traffic Safety Administration. An officer may use this test during a DUI stop to assess the subject's condition. If an officer performed the horizontal gaze nystagmus test during your traffic stop, resulting in your DUI case, you may benefit from consulting with an Orange County DUI lawyer.

The test requires the officer to evaluate the rhythmic oscillation of the subject's eyeballs. Though all people normally have slight, involuntary oscillation of their eyes, a more pronounced motion may signify the presence of alcohol in the subject's system. The officer looks for clues to show a horizontal gaze nystagmus: a jerky, sporadic movement of the eye toward the direction of the subject's gaze.

The test relies on three clues to show a horizontal gaze nystagmus. The officer looks for: (1) a lack of smooth pursuit; (2) distinct nystagmus at maximum deviation; and (3) the onset of nystagmus prior to an angle of 45 degrees. The officer makes two passes and identifies each of the three clues during each pass, which allows for a total of six clues. If the officer notices at least four clues, the officer may determine the subject's blood alcohol concentration as higher than 0.10 percent.

Barney Gibbs may be able to assist you in challenging the results of a horizontal gaze nystagmus test in your case. A lawyer may argue that interference from strobe lights, rotating lights, or the lights of passing cars may have changed the motion of your eyes. A lawyer may also try to cast doubt onto the test by explaining that dust and other irritants may have affected your eye movements. Furthermore, your lawyer may explain that other causes, including consumption of caffeine, nicotine, or aspirin, as well as fatigue, may lead to a nystagmus.

If you are facing a DUI trial, do not hesitate to contact experienced Orange Country DUI lawyer Barney Gibbs today to schedule a free initial consultation. I may be able to help you with your legal case.