What behavior might indicate a subject is impaired during the SFST?

The observation of poor coordination is a key indicator of impairment during the Standardized Field Sobriety Test (SFST). Impairment from substances, particularly alcohol, often results in difficulties with motor skills and balance. When an individual exhibits poor coordination, it can manifest as stumbling, difficulty maintaining balance, or challenges in performing tasks that require precise movements.

This behavior suggests that the person may not be able to perform basic physical tasks that are integral to safe driving, thus raising concerns about their ability to operate a vehicle safely. In contrast, clear speech, quick responses, and a calm demeanor may not reliably indicate sobriety, as individuals can sometimes mask impairment or exhibit these characteristics while still being affected by substances. Therefore, observing a lack of coordination is a critical factor in assessing impairment accurately during the SFST.