Tennessee Code Title 8. Public Officers and Employees § 8-35-251

(a) The chief governing body of any political subdivision participating in the retirement system may by resolution, legally adopted and approved by a two-thirds ( 2/3 ) majority of that body, elect to discontinue the mandatory retirement provisions of § 8-36-205 for all its firefighters and police officers, and for anyone who has been transferred from such a position to a supervisory or administrative position within the police or fire department of the political subdivision. All such employees who were employed prior to the effective date of the resolution will continue to be subject to the mandatory retirement provisions of § 8-36-205 and will continue to be eligible for the supplemental bridge benefit established pursuant to § 8-36-211. Such resolution shall set forth the effective date of the discontinuance; provided, that the date shall be on the first day of any quarter following a minimum of three (3) months' notice to the retirement system.

(b) Any resolution to discontinue the mandatory retirement provisions of § 8-36-205 that is adopted pursuant to this section shall be irrevocable and the political subdivision shall not be permitted to elect at a later date to provide the mandatory retirement provisions of § 8-36-205.