Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 37, § 11

Sheriffs and their deputies shall serve and execute, within their counties, all precepts lawfully issued to them and all other process required by law to be served by an officer. They may serve process in cases wherein a county, city, town, parish, religious society or fire or other district is a party or interested, although they are inhabitants or members thereof.