Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.229

Sec. 229. Decisions of the supreme court, including all cases of mandamus, quo warranto, and certiorari, shall be in writing, with a concise statement of the facts and reasons for the decisions; and shall be signed by the justices concurring in the opinion. Any justice dissenting from a decision shall give the reasons for his dissent in writing under his signature. All opinions and dissents shall be filed in the office of the clerk of the supreme court, and copies of them shall be delivered by the supreme court reporter at the same time.