Mich. Comp. Laws § 290.725

Sec. 25. (1) At all reasonable times, the department shall have access to and the right to copy evidence relating to any person or action under investigation by it in connection with any failure or refusal to bargain or for engaging in unfair practices. (2) In case of refusal to obey a subpoena issued to any person under this act, the circuit court, upon application by the department, shall have jurisdiction to order the person to appear before the department to produce evidence or to give testimony on the matter under investigation, and any failure to obey the order may be punished by the court as a contempt. (3) Complaints, orders, and other processes and papers of the department under this act may be served personally, by registered mail, or by leaving a copy thereof at the principal office or place of business of the person required to be served. The verified return of service shall be proof of the service. Witnesses summoned before the department shall be paid the same fee and mileage allowance that are paid witnesses in circuit court and witnesses whose depositions are taken, and the person taking the same shall be entitled to the same fees as are paid for like services in circuit court. (4) All processes of any court to which an application or petition may be made under this act may be served at any place in the state wherein the person or persons required to be served reside or may be found.