Tenn. Code Ann. § 55-4-222

An owner or lessee of a motor vehicle who is a resident of this state and who is a duly elected sheriff, upon complying with state motor vehicle laws relating to registration and licensing of motor vehicles, payment of the regular license fee for plates, as prescribed under § 55-4-111, and payment of the additional fee provided for in § 55-4-204, shall be issued a registration plate which shall bear the number of the sheriff's county of jurisdiction and the word “SHERIFF” in capital letters.