Mich. Comp. Laws § 399.212

Sec. 12. This act does not affect any previously enacted legislation pertaining to historical preservation and does not affect historical commissions appointed by local governing bodies to foster historic preservation. An existing local historical commission organized under Act No. 213 of the Public Acts of 1957, as amended, being sections 399.171 and 399.172 of the Compiled Laws of 1948, may be designated as a historic district commission, if its membership and structure conform, or are revised to conform, to the provisions of section 4.