Field sobriety exercises are the portion of the DUI arrest that occurs after law enforcement has reasonable suspicion that a DUI has occurred but before arrest. There are three standard exercises: the walk and turn, the one leg stand and horizontal gaze nystagmus. Generally horizontal gaze nystagmus or HGN is performed prior to the other two exercises. All of these exercises must be voluntary. Physical field sobriety exercises are not mandatory under Florida’s implied consent law. A person can legally refuse to complete these exercises without any mandatory statutorily prescribed license suspension. However, failure or refusal to complete these field sobriety exercises can be used by the State in a prosecution for DUI. Law enforcement will generally not inform a driver that these exercises are not mandatory. It is even possible that law enforcement misunderstand these exercises are not mandatory and inform a driver that these exercises are mandatory under Florida’s implied consent law.
There are several field sobriety exercises which are called supplementary field sobriety exercises. Commonly, these exercises are not included in a standard DUI investigation. If these exercises are necessary as determined by the law enforcement officer it is possible that the law enforcement officer has not formed probable cause based on his/her observations and the standard field sobriety exercises, or that the officer is not confident in his determination at this point. As that is the case, commonly these exercises are not performed. Some examples of supplementary field sobriety exercises are the Romberg Alphabet Test and the Finger to Nose Test. In boating under the influence cases or BUI, other supplemental exercises are included in the BUI investigation as the BUI investigation does not always occur on flat ground.
All field sobriety exercises are referred to as divided attention exercises. A divided attention exercise is designed to ask the subject to perform a task which requires a coinciding mental and physical task. Performance on these exercises is rated based on a clue system. The officer calculates clues observed. While these exercises are designed to eliminate the officers subjective judgment, often performance on these exercises is judged based on subjective observations.