How long must a subject stand on one leg during the One-Leg Stand test?

In the One-Leg Stand test, the subject is required to maintain their balance on one leg for a duration of 30 seconds. This timeframe is critical for observing the subject's ability to balance, which can indicate potential impairment due to alcohol or other substances. During these 30 seconds, the officer looks for specific indicators of impairment, such as swaying, using arms for balance, hopping, or putting the foot down. A duration of 30 seconds strikes a balance between being long enough to assess balance effectively while still being reasonable for the subject to attempt without being excessively taxing or long, which could lead to fatigue affecting their performance.