The county legislative body may exercise the powers of a legislative nature granted to it by the General Assembly in public acts (laws of general application or local option application, which may be found in codified form in the Tennessee Code Annotated) or in private acts that apply to a particular county (that do not conflict with the general law). The General Assembly has given the county legislative body a considerable array of powers, including the power to levy property taxes without limitation regarding rates, the power to expend funds for any lawful purpose, zoning powers for the unincorporated areas of the county and some regulatory powers, yet the General Assembly has not seen fit to grant to the county legislative body all of the powers that have been granted to Tennessee's incorporated municipalities (cities and towns). Therefore, counties must always look for the source of authority for any action taken, as counties have no authority to act outside the scope of the powers granted by the General Assembly.

The General Assembly has given the Title "county commissioner" to all county legislative body members not in a county with a consolidated city/county government. T.C.A. § 5-5-102(f).