Michigan Compiled Laws, Chapter 45. Counties § 45.502

Sec. 2. The board of supervisors of any county, by a majority vote of its members elect may, or upon petition of 5% of the registered electors of the county shall, adopt a resolution providing for the submission of the question of electing a charter commission for the purpose of framing and submitting to the electorate a county home rule charter. The petition shall be addressed to the board of supervisors and shall be filed with the clerk of the board not less than 30 days prior to the convening of a regular session of the board or to the convening of any special session called for the purpose of considering the petition.