Mich. Comp. Laws § 780.656: Service of warrant; officer's authorization to use force.

Sec. 6.

The officer to whom a warrant is directed, or any person assisting him, may break any outer or inner door or window of a house or building, or anything therein, in order to execute the warrant, if, after notice of his authority and purpose, he is refused admittance, or when necessary to liberate himself or any person assisting him in execution of the warrant.