Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.1621

(a) The county in which a defendant resides, has a place of business, or conducts business, or in which the registered office of a defendant corporation is located, is a proper county in which to commence and try an action.

(b) If none of the defendants meet 1 or more of the criteria in subdivision (a), the county in which a plaintiff resides or has a place of business, or in which the registered office of a plaintiff corporation is located, is a proper county in which to commence and try an action.

(c) An action against a fiduciary appointed by court order shall be commenced in the county in which the fiduciary was appointed.