Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 41, § 98A

A police officer of a city or town who is empowered to make arrests within a city or town may, on fresh and continued pursuit, exercise such authority in any other city or town for any offence committed in his presence within his jurisdiction for which he would have the right to arrest within his jurisdiction without a warrant. Said officer may return any person so arrested to the jurisdiction wherein said offence was committed. Nothing contained in this section shall be construed as limiting the powers of a police officer to make arrests and in so far as possible this section shall be deemed to be declaratory of the common law of the commonwealth.