Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 148, § 4

The marshal, the head of the fire department, or any person to whom the marshal or the head of the fire department may delegate the authority, may, in the performance of the duties imposed by this chapter, or in furtherance of the purpose of any provision of any law, ordinance or by-law relating to the subject matter of this chapter, or of any rule or regulation of the board of fire prevention regulations, established under section four of chapter twenty-two D, in this chapter referred to as the board, or any order of the marshal or head of the fire department, enter at any reasonable hour any building or other premises, or any ship or vessel, to make inspection or investigation, without being held or deemed to be guilty of trespass.

The marshal or the head of a fire department to whom he may delegate authority, shall make an inspection every three months of institutions as defined by the state building code, licensed by and under the supervision of the department of public health, or licensed by the department of public welfare, and shall make a report of such inspection to each such department on forms submitted to the marshal by such department for this purpose. Said marshal of such head of a fire department shall also make an inspection every three months of the premises specified in innholder's licenses issued under chapter one hundred and forty.