Mich. Comp. Laws § 801.257: Reduction of term.

Sec. 7.

Except as provided in section 5 of the prisoner reimbursement to the county act and section 5a of chapter 171 of the Revised Statutes of 1846, being section 801.5a of the Michigan Compiled Laws, a prisoner may receive, if approved by the court, a reduction of 1/4 of his or her term if his or her conduct, diligence, and general attitude merit such reduction.