Prior to making an arrest for Driving Under the Influence, the officer must develop probable cause to support the decision to make the arrest. One of the chief means of doing this is by making the suspected impaired driver submit to Field Sobriety Exercises.
Standardized Field Sobriety Test (SFST) is a battery of three tests administered and evaluated in a standardized manner to obtain validated indicators of impairment and establish probable cause for arrest. These tests, also referred to as “exercises” were developed as a result of research sponsored by the National Highway Traffic Safety Administration (NHTSA). A formal program of training was developed by NHSYA in order to help police officers become more skillful at detecting DUI suspects, describing the behavior of these suspects, and presenting effective testimony in court.
The three most commonly used standardized exercises are:
- The Horizontal Gaze Nystagmus (HGN)
- The Walk-and-Turn
- The One-Leg Stand
Horizontal Gaze Nystagmus
Horizontal gaze nystagmus is an involuntary jerking of the eyeball which occurs naturally as the eyes gaze to the side. Under normal circumstances, nystagmus occurs when the eyes are rotated at high peripheral angles. In theory, when someone is under the influence of alcohol nystagmus is exaggerated and may occur at lesser angles. An alcohol-impaired person is supposed to have difficulty smoothly tracking a moving object. In the HGN exercise, the officer observes the eyes of a suspect as the suspect follows a slowly moving object such as a pen horizontally with his eyes.
While Florida Courts have upheld the validity of this exercise it is not always an indication of impairment as there are numerous causes of nystagmus other than alcohol in a person’s system.
Divided Attention Exercises
The WALK-AND-TURN and the ONE-LEG STAND EXERCISES are “divided attention” exercises. By divided attention this means that the exercise requires a person to pay attention, remember and follow the instructions to the exercise while actually physically performing this task. In theory these exercises are easily performed by most sober people. But this is not always true. If you have a physical disability or a physical limitation this may invalidate certain physical field sobriety exercises.
The National Highway Traffic Safety Administration (NHTSA) sets forth certain requirements for the administration of field sobriety exercises. It is important that the officer determine whether a person has a physical limitation or injury before making someone perform field exercises. In fact the Standardized Field Sobriety Testing Manual states: “The officer may wish to use discretion when administering the ONE LEG STAND and WALK AND TURN to persons over 65 years of age, 50 pounds or more overweight, or who have physical impairments which affect their ability to balance. (Administer alternate exercises if the subject meets these criteria.) Individuals wearing heels more than two inches high should be given the opportunity to remove their shoes.”
As you can see there may be several reasons why someone is unable to perform these divided attention exercises to the officer’s satisfaction.
