Tenn. Code § 65-158
Subject to the administrative duties reserved by state law to the state treasurer with respect to all state retirement systems, the board of trustees shall have complete control of the administration of the public service commissioners' retirement system, subject to the provisions of §§ 65-151 - 65-168, with all powers necessary to enable it to carry out properly its duties in that respect. The members of the board shall serve without compensation as board members but shall be reimbursed for actual expenses incurred by them in the performance of their duties. The board shall be fully protected with respect to any action taken or suffered by the board in good faith and reliance upon any table, valuation, certificate, report, advice or opinion furnished by any consultant or actuary, opinions given by the state attorney general or an assistant thereof, or the advice of any qualified investment consultant, and all action so taken or suffered by the board shall be conclusive upon each member of the board and upon all commissioners or persons interested in the public service commissioners' retirement system.
T.C.A. § 65-158