Fields Sobriety Tests (FSTs) are tests designed to allow police officers in the field to determine whether a driver is under the influence of alcohol. The National Highway Traffic Safety Administration (NHTSA) is a U.S. government agency that developed a number of standardized tests that they recommend police officers use to evaluate drivers they suspect of DUI. NHTSA suggests that officers perform three FSTs to evaluate San Diego DUI suspects. The suggested tests are the one leg stand, the walk and turn, and the Horizontal Gaze Nystagmus (HGN). Unfortunately, many police officers deviate from the NHTSA recommended tests and, as a result, the tests they perform are unreliable. For example, officers often fail to give the NHTSA recommended instructions or look for the NHTSA recommended clues. The signs that officers look for in order to determine whether a person is under the influence are called clues. The officers’ deviation from the NHTSA recommended procedures can be a used to reduce the perceived accuracy of the FST results at trial.
Walk and Turn
For the walk and turn test, an officer should instruct a suspect to walk along a straight line for 9 steps, heel to toe, arms at sides, while looking at feet, turn around by taking a series of small steps with one foot and keeping the other foot on the ground and walk back to the starting position.
The police officer should look to see whether the suspect loses his balance while waiting for the start of the test, starts to soon, stops walking during the test, misses heel-to-toe, steps off the line, raises arms while walking, takes the wrong number of steps, or turns improperly.
One Leg Stand
For the one leg stand test, an officer should instruct a suspect to raise his leg 6 inches off the ground, keep his raised toe pointed forward, hold his arms at his sides, look at his raised foot, and count “one-one-thousand” and so on until he is instructed to stop.
The police officer should look to see whether the suspect puts his foot down during the test, hops, uses his arms to balance, or sways side to side or front to back.
Horizontal Gaze Nystagmus (HGN)
For the HGN test, an officer should instruct a suspect to stand with his arms at his sides, feet together, and keep his head still during the test. The officer should place a stimulus (such as a pen) 12 to 15 inches from the suspect’s nose, just above eye level, and pass the stimulus back and forth across the suspect’s field of vision a specific number of times at a specific rate of speed. Officers often make mistakes as to the speed at which they move the stimulus, how far they move it, and the number passes across the persons face they make with the stimulus.
Clues a San Diego DUI attorney should know:
For the HGN test, the officer should look for these clues: lack of smooth pursuit, distinct nystagmus at maximum deviation, and onset of nystagmus prior to 45 degrees. The eyes of a person who is not impaired should move like a marble rolling across a smooth surface, like glass. When a person is impaired, his eyes may move like a marble across sandpaper, shaking very slightly back and forth as they move along. This shaking is called a lack of smooth pursuit. Maximum deviation is the point at which a person’s eyes can not turn any further to one side. A person who is impaired may exhibit a more pronounced bouncing or shaking of his eyes at maximum deviation than the shaking observed when his eyes are not turned as far as they can go. An person’s eyes should move relatively smoothly until they have turned about 45 degrees. A person who is impaired may display shaking or bouncing before the eyes have turned more than 45 degrees to either side.