Mass. Gen. Laws ch. 159, § 34: Examination of books, etc.; subpoena duces tecum

Section 34. The department, through its commissioners or by employees duly authorized, may examine all books, contracts, records, documents, papers and memoranda of any common carrier, and by subpoena duces tecum compel the production thereof, or of duly verified copies of the same or any of them, and compel the attendance of such witnesses as the department may require to give evidence at any such examination.