Mich. Comp. Laws § 397.157

Sec. 7. Cities of a population of 5,000 or more, maintaining a public library, may be exempted from the provisions of this act on the filing with the state board for libraries of a request by the city legislative body based on action taken by them according to law. Where any such city is included in any regional library proposal the state board for libraries shall notify each city so included in writing of the provisions of this section 15 days before the reference of any regional library proposal under the provisions of section 2.