Mich. Comp. Laws § 462.44: Police powers vested in commission.

Sec. 44.

The police powers of the state over railroads, street railways, interurban railways and suburban street railways, whether operated by steam, electricity or other motive power, organized or doing business in this state, shall be and the same are hereby vested in the railroad commission, and it is hereby made the duty of said railroad commission to exercise the same in accordance with the requirements of the law.