Tennessee Code Title 55. Motor and Other Vehicles § 55-2-110

(a) The commissioner and officers of the department designated by the commissioner have the authority to summon witnesses to give testimony under oath or to give written depositions upon any matter under the jurisdiction of the department. Each summons may require the production of relevant books, papers, or records.

(b) Every summons shall be served at least five (5) days before the return date, either by personal service made by any person over eighteen (18) years of age or by registered mail, but return acknowledgment is required to prove service by registered mail.

(c) Failure to obey the summons served shall constitute a misdemeanor.

(d) The fees for the attendance and travel of witnesses shall be the same as for witnesses before the circuit court.