Michigan Compiled Laws, Chapter 38. Civil Service and Retirement § 38.101

Sec. 1.(1) Except as otherwise provided in section 1a of this article,  1 discharge or demotion of a teacher on continuing tenure may be made only for a reason that is not arbitrary or capricious and only as provided in this act.

(2) This act does not prevent any controlling board from establishing a reasonable policy for retirement to apply equally to all teachers who are eligible for retirement under the public school employees retirement act of 1979, 1980 PA 300, MCL 38.1301 to 38.1437, or, having established a reasonable retirement age policy, from temporarily continuing on a year-to-year basis on criteria equally applied to all teachers the contract of any teacher whom the controlling board might wish to retain beyond the established retirement age for the benefit of the school system.