Mass. Gen. Laws ch. 147, § 14: Days off for police; one day out of thirty

Section 14. Members of the police department of every city, except Boston and such cities as have accepted chapter two hundred and ten of the acts of nineteen hundred and eleven or chapter one hundred and sixty-six of the acts of nineteen hundred and twenty, and of every town which accepted chapter four hundred and seventy-six of the acts of nineteen hundred and eight and afterward did not accept chapter two hundred and ten of the acts of nineteen hundred and eleven or chapter one hundred and sixty-six of the acts of nineteen hundred and twenty, shall be excused from duty for one day out of every thirty without loss of pay.