Observation hold is a practice used by law enforcement and medicine to decide whether or not someone who has been taken into custody is suffering from mental health issues. Although laws differ between jurisdictions a person can generally be held for as many as 72 hours in a mental health facility while their behavior and mental status is observed and evaluated. At the end of the observation period, a decision is made in regard to whether the person can be released, continue under arrest, or held for further observation.
For instance, police are called to a scene where someone has barricaded himself in a house and is threatening suicide. Once action is taken and the person is now safe in police custody, the police officers might be directed to transport the individual to the nearest hospital for a medical opinion. He could then be be held for observation in a psychiatric unit.