Tennessee Code Title 5. Counties § 5-9-310

(a) The county mayor, after the bills referred to in § 5-9-308 have been examined and approved by the judge and district attorney general, is granted full power, and it is made the county mayor's duty, to examine into, inspect and audit all bills of cost accruing against the county, and disallow any part of the bills of cost that may be illegally or wrongfully taxed against the county.

(b) The county mayor may disallow any and all costs taxed against the county on account of malicious, frivolous, or unnecessary prosecution, in the event the judge and district attorney general should, by mistake or otherwise, approve any of such bills.