Driving Under the Influence of Drugs HGN Test

If you are ever pulled over by an officer who suspects you are driving under the influence of drugs, he or she may ask you to perform a series of field sobriety tests to determine whether you are indeed intoxicated. Most likely, one of these exercises will be the horizontal gaze nystagmus, or HGN, test.

Nystagmus is a term used to describe a natural condition of the eye that occurs when an individual’s head is titled forward and looking in a specific direction. When present, nystagmus causes the eyes to involuntarily jerk or twitch. Consuming alcohol and/or drugs, in turn, can greatly exacerbate the condition.

During an HGN test, the officer will carefully watch the subject’s eyes to look for three specific signs of nystagmus—inability to follow the object, marked jerking of the eyes, and any twitching within a 45-degree angle of the center of the eye. If the officer observes four or more of these indicators, the individual will most likely be arrested and charged with driving under the influence of drugs.

Although alcohol and/or drug use can often exacerbate the appearance of nystagmus, there are actually 47 different conditions that can cause this phenomenon. For example, individuals with vision problems may exhibit nystagmus while they are sober; the same is true for people with neurological conditions, such as epilepsy or vertigo.

Despite the varying causes of nystagmus, the horizontal gaze nystagmus test is one of three field sobriety tests that have been approved by the National Highway Traffic and Safety Administration (NHTSA) for use in determining whether an individual is intoxicated. Nevertheless, studies show that the horizontal nystagmus test is only accurate for approximately 77% of individuals.

In addition to frequent unreliability, the horizontal gaze nystagmus test is often administered incorrectly. The object of focus, for example, should be no more than fifteen inches in front of the subject’s face, and the officer should check with him or her to ensure the object is a comfortable distance away from the subject. Eyeglasses and hard contact lenses must also be removed while the test is administered. Finally, the object used in the test must be raised above eye level.

If you were recently charged with driving under the influence of drugs after taking an HGN test, it is important to seek legal representation immediately. An experienced criminal attorney will not only determine the best defense for your case, but in many cases, he or she may even be able to reduce or eliminate the charges against you. If the officer who arrested you did not follow NHTSA guideline for administering the test, for example, your results may be inadmissible during trial.

Protect your rights and improve your chances for obtaining a favorable outcome in court. Discuss your HGN test results with a skilled attorney in your area today.