Massachusetts General Laws Part III. Courts, Judicial Officers and Proceedings in Civil Cases (Ch. 211-262) Ch. 248, § 37

Upon the filing of such petition, the court shall cause notice to be served upon all the supposed custodians or persons alleged to be detaining or holding in custody said person, as stated in said petition, or as otherwise known, ordering them to appear before said court at a time and place named therein, to be examined as said court shall order; and may cause said person to be brought before it for examination as to his desire to be released and as to any other relevant matters.