Tenn. Code Ann. § 27-8-101: Constitutional basis

The writ of certiorari may be granted whenever authorized by law, and also in all cases where an inferior tribunal, board, or officer exercising judicial functions has exceeded the jurisdiction conferred, or is acting illegally, when, in the judgment of the court, there is no other plain, speedy, or adequate remedy. This section does not apply to actions governed by the Tennessee Rules of Appellate Procedure.