Tenn. Code § 8-3601
The chief legislative body of any political subdivision of the state of Tennessee may, by resolution legally adopted and approved by said chief legislative body, elect to authorize all its employees, or former employees, in any of such of its departments or instrumentalities as it may desire to become eligible to participate in the "Tennessee state retirement system," provided that such participation shall be subject to the approval of the board and in conformity with such rules and regulations as may be prescribed by the board and shall in no case become effective before July 1, 1949; provided, further, however, that the entire employer contribution for such public employees, or former employees, shall be provided and paid by the political subdivision and not by the state, and provided, that said employees, or former employees, will not have a voice in the election of the board. After such election and approval to become members of the retirement system, such body shall thereafter be known for the purposes of chapters 34 and 35 of this title as an employer. Acceptance of the employees, or former employees, of such political subdivision for membership in the retirement system shall be optional with the board, and if it shall approve their participation, then such employees, or former employees, may become members of the retirement system and participate therein as provided in the provisions of this chapter.
Notwithstanding anything to the contrary in chapters 34 and 35 of this title, the chief legislative body of any political subdivision electing after June 30, 1971, to authorize its firemen and policemen to participate in the Tennessee state retirement system, may, in its resolution adopted pursuant to this section, elect to have firemen and policemen treated as regular Class A employees.
Should the Tennessee Counties Services Association request that its administrative employees be permitted to become members of this retirement system and should the association agree to make in behalf of its employees the employer's contributions required under this chapter, such employees shall be considered as employees for the purpose of this retirement system and shall be eligible for membership herein. They shall make the same contributions and shall be eligible to the same benefits as state employees who are members. They shall be allowed such credit for service as shall be certified and paid for by the association. The association shall make current service contributions and special accrued liability contributions corresponding to the contributions payable by the state. The special accrued liability contributions shall be determined by an actuarial valuation of the accrued liability on account of the employees of the association who become members in the same way as the accrued liability contributions for employees of political subdivisions participating in the retirement system are determined; provided, however, that the accrued liability valuation shall include the total creditable service rendered by any such employee, less the value of the benefit heretofore accrued to such member on account of any service as a state employee. The contributions of the association shall be paid by the association at the same time and in the same manner as contributions are paid by participating political subdivisions, and all benefits payable to employees of the association shall be contingent upon the payment of the necessary contributions by the association and its employees.
Any regional library board may, by resolution duly adopted, elect to authorize its employees to participate in the Tennessee state retirement system, subject to the approval of the board of trustees of the retirement system and subject to and in conformity with such rules and regulations as may be prescribed by the board of trustees. The entire employer contribution for such employees shall be paid by the regional library board as employer out of whatever funds are available to the board for that purpose. Such employees shall not have a voice in the election of the board of trustees. After the adoption of such a resolution by a regional library board and approval by the board of trustees of the system, the library board shall thereafter, for the purposes of chapters 34 and 35 of this title, be an employer, and employees of the board shall be employees for the purposes of such chapters and shall be eligible for participation in the retirement system. They shall make the same contributions and shall be eligible for the same benefits as state employees who are members. They shall be allowed such credit for service as shall be certified and paid for by the library board. The library board shall make current service contributions and special accrued liability contributions corresponding to the contributions payable by the state. The special accrued liability contributions shall be determined by an actuarial valuation of the accrued liability on account of the employees of the library board who become members in the same way as the accrued liability contributions for employees of political subdivisions participating in the retirement system are determined. The accrued liability valuation shall include the total creditable service rendered by any such employee, less the value of the benefit heretofore accrued to such member on account of any service as a state employee. The contributions of the library board shall be paid by the board at the same time and in the same manner as contributions are paid by participating political subdivisions of the state. All benefits payable to employees of the association shall be contingent upon the payment of the necessary contributions by the library board and its employees.
The Tennessee state retirement system may include therein under authority of this chapter the employees of the University of Tennessee who are not included in the University of Tennessee retirement system but who otherwise meet eligibility requirements under this chapter, and the University of Tennessee is authorized to establish for retirement classification purposes such department or departments as it deems necessary to classify such employees for eligibility to participate in the Tennessee state retirement system. For the purposes of this chapter only, the University of Tennessee shall be considered as a political subdivision.
T.C.A. § 8-3601