Tenn. Code Ann. § 49-5-604: Rights preserved

(a) Those rights and responsibilities of boards of education, directors of schools and professional employees as contained in this title are not statutorily modified or repealed by this part.

(b) This part shall not operate so as to annul or modify any recognition heretofore entered into between a board of education and a professional employees' organization until the termination of an existing agreement between a local board of education and a professional employees' organization. Upon the termination of any existing agreement, subsequent professional employee relationships between the respective board of education and its professional employees shall be governed by this part.