Tenn. Code Ann. § 12-3-504

The chief procurement officer shall identify goods or services that may not be procured by competitive means because of the existence of a single source of supply. The chief procurement officer shall submit to the procurement commission for approval rules, policies, and procedures prescribing the manner in which such procurements may be accomplished, which may include noncompetitive negotiation. Sole source goods and services shall be purchased only in accordance with these rules, policies, and procedures approved by the procurement commission.