Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.2912d

(1) Subject to subsection (2), the plaintiff in an action alleging medical malpractice or, if the plaintiff is represented by an attorney, the plaintiff's attorney shall file with the complaint an affidavit of merit signed by a health professional who the plaintiff's attorney reasonably believes meets the requirements for an expert witness under section 2169. The affidavit of merit shall certify that the health professional has reviewed the notice and all medical records supplied to him or her by the plaintiff's attorney concerning the allegations contained in the notice and shall contain a statement of each of the following:

(2) Upon motion of a party for good cause shown, the court in which the complaint is filed may grant the plaintiff or, if the plaintiff is represented by an attorney, the plaintiff's attorney an additional 28 days in which to file the affidavit required under subsection (1).

(3) If the defendant in an action alleging medical malpractice fails to allow access to medical records within the time period set forth in section 2912b(6), the affidavit required under subsection (1) may be filed within 91 days after the filing of the complaint.