Tenn. Code Ann. § 33-4-106: Unauthorized leave from facility

(a) If a person admitted under court order leaves a hospital or residential service without authority, the chief officer shall immediately notify the court regardless of the length of the person's absence. If the person is taken into custody, the person may be returned to the facility upon an order by the court. After thirty (30) days absence the person may be dropped from the facility's records. A return after thirty (30) days absence is a new admission. A person's absence beyond thirty (30) days does not limit the power of the court to order the person's return to a facility under this section.

(b) The committing court shall be notified of the policy regarding temporary leave, and the court shall be given an opportunity to register its objection to granting temporary leave. An objection by the court does not prohibit authorization of leave. Temporary leave is not a discharge from the facility.