Tenn. Code Ann. § 8-8-221: Sheriffs to regulate incarcerations in county jails and to register persons acting as law enforcement officers

(a) The sheriff of each county shall establish regulations governing the acceptance of persons, other than state prisoners, for incarceration in the county jail. Except for state prisoners held in the county jail, no person shall be incarcerated in the county jail without the approval of the sheriff, or the sheriff's designee, subject to approval of the court having criminal jurisdiction over the sheriff's jurisdiction, as provided by regulation.

(b) Except for duly commissioned state and municipal law enforcement officers, no person shall go armed for law enforcement purposes, carry or display a badge or other card or device purporting to identify that person as an officer of the law, wear any uniform or distinctive clothing purporting to identify that person as an officer of law, or mark any motor vehicle so as to identify it as a law enforcement vehicle, or its driver as a law enforcement officer, without registering each and any of these acts with the sheriff of the county in which such acts take place, and complying with reasonable regulations established by the sheriff to properly and consistently identify all persons in that county exercising law enforcement powers.

(c) This section applies only to counties having a population of not less than nine thousand (9,000) nor more than nine thousand one hundred (9,100), according to the 1970 federal census or any subsequent federal census, and to counties having a population of not less than seven hundred seventy thousand (770,000) nor more than seven hundred eighty thousand (780,000), according to the 1980 federal census or any subsequent federal census.