Mich. Comp. Laws § 120.104

Sec. 4. (1) A city and county, a combination of counties or a combination consisting of at least 1 city and 1 county, by joint resolution of their respective governing bodies, may request the governor to authorize the incorporation of an authority. The governor shall consider the recommendations of the department of state highways and transportation and the department of commerce in authorizing the authority. The initial articles of incorporation shall be approved by the governor and may thereafter be amended by resolution of the authority, subject to approval by the governor. After approval by the governor, the articles of incorporation and any amendments to those articles shall be effective upon filing with the secretary of state. (2) An authority created under this act shall be a body corporate and politic. (3) The exercise by an authority of the powers conferred by this act shall be considered and held to be an essential governmental function and a benefit to, and a legitimate public purpose of the state, the authority, and the constituent units.