Mass. Gen. Laws ch. 22C § 52
A record of all such appointments, made pursuant to section fifty-one, shall be kept by the department, and shall be open to public inspection, and such appointment shall constitute the person or persons named therein railroad, railway, railway express or steamboat police, respectively, in any city or town where the petitioner corporation or company referred to in section fifty-one operates its cars, vehicles, boats or vessels, or the carrier so referred to is accustomed to receive or discharge passengers or freight, or steamboat police upon the premises and at the wharves and landing places and upon the boats and vessels of such carrier by water, while within the boundaries of the commonwealth, and shall be conclusive evidence of the regularity of their appointment.
Mass. Gen. Laws ch. 22C, § 52