Tennessee Code Title 8. Public Officers and Employees § 8-35-101

(a)(1) Any person who becomes a teacher, a general employee, a state police officer, a wildlife officer, a firefighter or a police officer on or after July 1, 1972, shall become a member of the retirement system as a condition of employment.

(2) Notwithstanding this section or any other law to the contrary, no state department, commission, institution, board, agency, instrumentality or entity of or affiliated with state government shall be authorized to cover its otherwise eligible employees in the retirement system unless the general assembly approves the annual operating budget for the entity, or unless the entity has specific Tennessee state statutory authority to cover its otherwise eligible employees in the retirement system and the entity obtains written advice from nationally recognized counsel employed by the retirement system in the area of government employee benefit plans that the entity is eligible to participate in a governmental plan as defined by Internal Revenue Code § 414(d) (26 U.S.C. § 414(d)), as amended. The foregoing also applies to any person seeking admission to the retirement system whose compensation is paid, in whole or in part, from funds not appropriated by the general assembly. Notwithstanding this section or any other law to the contrary, the funds necessary to fund any prior service of such persons must be appropriated by the general assembly or paid by another governmental entity.