Mass. Gen. Laws ch. 41 § 111H
Notwithstanding the provisions of any general or special law to the contrary, any police officer of a city or town who is required to perform any service beyond his regular established hours of service on primary day, on election day, on the thirty-first day of October or at any parade or race or at any public celebration or while police listing, shall be compensated for such additional hours of service at the rate per hour of his regular compensation. This section shall take effect in a city having a Plan E charter when accepted by the affirmative vote of a majority of the city council, and in the case of other cities by vote of the council, subject to the provisions of its charter, and in a town by a majority vote at an annual town meeting. The rate per hour of his regular compensation referred to in this section shall be based on the number of hours worked in an average week.
Mass. Gen. Laws ch. 41, § 111H