Any judge who complies with the foregoing applicable requirements for retirement shall thereupon be entitled to receive, during the remainder of his life, a pension in an amount determined according to the provisions of this judges' retirement system, but in no event shall he receive a pension smaller in amount than he would have received under the retirement laws in effect on January 1, 1970, had they been in effect at the time of his retirement.
T.C.A. § 17-328