In the one leg stand test, how long must the subject hold their leg up?

The one leg stand test is a common field sobriety test used by law enforcement to assess a subject's balance and coordination, which can be indicators of impairment. The standard duration for the subject to hold their leg up is 30 seconds. This time frame allows enough observation for law enforcement officers to evaluate the subject's physical stability and ability to follow directions, which may be impaired if under the influence of alcohol or drugs. Observations are made on how well the subject can maintain balance, as well as any signs of swaying or needing to hop to maintain balance. Holding the leg up for 30 seconds provides a sufficient period to effectively assess these behaviors.