Tennessee Code Title 5. Counties § 5-21-120

(a) The committee shall authorize the dollar limitation when formal competitive bids are required but not to exceed the amount as authorized by state law for the highway and education departments or other such amounts as established by law.

(b) Subject to the policies and regulations of the committee, “biddable items” means any need of the county where more than one (1) bidder or contractor in the county's trade area can provide the material or service. Specifications shall not be written to exclude vendors and contractors or limit the bidding to a specific vendor or contractor.

(c) The county shall be liable for the payment of all purchases of supplies, materials, equipment and contractual service made in accordance with this chapter, but shall not be liable for the payment of such purchases made contrary to its provisions unless such item is specifically approved by the committee.