Tenn. Code Ann. § 8-34-204: Amendment or repeal of laws not to diminish or annul acquired rights

Every provision of chapters 34-37 of this title shall be subject to amendment or repeal by any session of the general assembly; provided, that no such amendment or repeal shall diminish or annul, in any respect, any right acquired by a member or beneficiary under chapters 34-37 of this title.