New Hampshire Horizontal Gaze Nystagmus Test
To make a driving while intoxicated (DWI) arrest, a New Hampshire law enforcement agent must have probable cause to believe that the crime of drunk driving is being committed. One way to establish evidence that a driver is impaired is by administering a series of field sobriety tests. While there are a number of tests that may be used, such as reciting the alphabet backwards or closing your eyes and touching your nose, only three have been approved by the National Highway Traffic Safety Administration (NHTSA): the horizontal gaze nystagmus test, the one-leg stand test, and the walk-and-turn test.
Considered the most scientific of the three standardized field sobriety tests, the horizontal gaze nystagmus test measures nystagmus (the involuntary jerking of the eyeballs), which becomes more evident when a person is under the influence of alcohol and/or drugs. To administer the test, the officer will ask you to keep your head still while following a small object, such as a pen or a penlight, with your eyes.
While you are performing the test, the officer will look for three clues in each eye. These include: inability to smoothly follow the stimulus with your eyes, pronounced nystagmus when your eyes are all the way to the side, and the onset of nystagmus prior to reaching 45 degrees. If the officer sees four out of six clues, he or she can then arrest you for DWI.
The New Hampshire horizontal gaze nystagmus test is not without its problems. If administered improperly, you may receive a failing grade—even if you aren’t impaired. In addition, there are a number of medical, neurological, and eye conditions that can cause this involuntary jerking. If this is the case, a DWI defense lawyer can challenge the results of this test.
Another problem with the field sobriety tests is that they are entirely subjective. The chances are that if an officer stops you on suspicion of drunk driving, he or she already believes that you are intoxicated. Unfortunately, this could be reflected in your test score.