Tenn. Code § 65-153
Any commissioner having ten (10) or more years of service and becoming disabled may, upon complying with other applicable requirements set out in §§ 65-151 - 65-168, apply for disability retirement and be retired under the provisions of this section and shall thereupon be entitled to receive, during the remainder of his life, a disability pension. The amount of any disability pension shall be determined in the same manner as a "normal retirement benefit" in accordance with § 65-152(g). Any commissioner who receives any disability retirement benefits under the provisions of this section shall not thereafter be eligible to continue in the same term of office as a commissioner. For the purposes of §§ 65-151 - 65-168 "disabled" or "disability" shall mean a permanent physical or mental disablement occurring during the term of office of a commissioner which, in the sole discretion of the governor of the state of Tennessee, prevents such commissioner from performing his duties as a commissioner.
T.C.A. § 65-153