Compiled Laws, Chapter 168. Michigan Election Law § 168.633

Sec. 633. The governor shall call a special election in any congressional district of the state when the right of office of a person elected representative in congress shall cease before the commencement of the term of service for which he shall have been elected, or whenever a vacancy shall occur in the office of representative in congress after the term of service has begun for which such representative was elected; or the governor shall direct that such vacancy shall be filled at the next general election to be held at least 30 days after such vacancy shall occur.