What does the "U" clue signify during the One Leg Stand test?

The "U" clue during the One Leg Stand test indicates that a person is using their arms for balance while attempting to maintain their position on one leg. This behavior is a notable sign during the sobriety test because it reveals that the individual is struggling to maintain their balance without assistance. Typically, a sober individual should be able to keep their arms at their sides while standing on one leg for the duration of the test. Utilizing arms for balance demonstrates a lack of physical coordination and control, which can be a strong indicator of impairment, especially in the context of assessing a person's capability to operate a vehicle safely.