What Are Field Sobriety Tests?

Field sobriety tests (FST's) are psychophysical tests used to assess a person's physical and/or mental impairment.

Horizontal Gaze Nystagmus (HGN)

This test for DUI in Fort Meade refers to the involuntary jerking of the eye as it gazes to the side. When this occurs, the person is unaware of the jerking, and cannot control it. This involuntary jerking becomes noticeable as persons' blood alcohol increases. This is the most reliable of the FST's. However, nystagmus is a natural, normal phenomenon. Alcohol and certain drugs do not cause this phenomenon.

When the HGN test is administered, the officer hold a stimulus (usually a pen) 12-15 inches in front of you eyes and asks you to follow the stimulus with your eyes, without moving your head. The officer will always start with the left eye and they are looking for 3 specific clues:

1. Lack of Smooth Pursuit:

As the eye moves from side to side, does it move smoothly or does it noticeably jerk (bounce)? The jerking is similar to how windshield wipers jerk across a dry windshield. There is a standardized pace the officer is to have the eyes move side to side. From the center of the face, they are to move the eye all the way out to the side in approximately 2 seconds, then 2 seconds back to center, approximately 2 seconds to the other side, and 2 seconds back to center. They are to repeat the procedure. If they have the eyes move too fast, not only are they performing the test improperly, the government has admitted tha

2. Distinct Nystagmus at Maximum Deviation: When the eye moves as far to the side as possible and is kept in that position for several seconds, is there distinct jerking (bouncing) of the eye. The eye is to be moved all the way to the side, and kept there a minimum of 4 seconds. Interestingly enough, some people exhibit slight jerking of the eye at maximum deviation even when unimpaired! Also, if the eye is moved to the side too quickly, this may cause the nystagmus.

3. Onset of Nystagmus Prior To 45 Degrees: As the eye moves towards the side, does it start to jerk (bounce) before it reaches a 45-degree angle? When moving the eye out to 45-degree's, the movement of the eye should take approximately 4 seconds to reach 45-degrees. It is important to take the full 4 seconds when checking for onset. If the stimulus is moved too fast, the officer could take your eye beyond 45 degrees, or if the eye is moved to 45-degrees too quickly, th

The maximum number of clues in each eye is 3, for a total of 6 clues. The original research has shown that if 4 or more clues are present, the person is intoxicated. This test has been shown to be accurate 77% of the time; therefore, it is inaccurate 23% of the time!

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