Tennessee Code Title 2. Elections § 2-9-117

The state coordinator of elections and the state election commission shall approve any voting machine before a county election commission purchases such machine. Before the 2002 election cycle and at least every eight (8) years thereafter, the state coordinator of elections and the state election commission shall reexamine all voting machines to ensure such machines still meet the minimum criteria for certification. If a particular machine is not recertified by the coordinator of elections and the state election commission, the affected county election commission shall have two (2) years to purchase and implement machines that are properly certified.