Mich. Comp. Laws § 6.10: Impeachment; writs and process, signing and testing, enforcement.

Sec. 10.

The writs and process of the senate sitting as a court for the trial of an impeachment, shall be signed by the secretary of the senate and tested in the name of the presiding officer, and the senate as such court shall have power to enforce obedience to its process by attachment and punishment as for contempt of the process of a court of record.