Mass. Gen. Laws ch. 221 § 62B
Clerks of court for the several counties, the clerk of the superior court for criminal business in Suffolk county, the clerk of the superior court for civil business in Suffolk county, clerks of the housing courts, registers of the probate courts, clerks of district courts, clerks of juvenile courts, and clerks of the Boston municipal court department; shall hereafter also have the title of magistrate for their particular department, or division as the case may be, of the trial court.
Magistrates herein provided shall continue to have and exercise all the powers, duties and responsibilities of clerks and registers and shall also have those provided for in section sixty-two C.
An assistant clerk, temporary clerk, temporary assistant clerk, or assistant register, shall also have and exercise the powers, duties and responsibilities of magistrate, subject to specific authorization by the clerk, or register, and specific approval of such authorization by the first justice of the division wherein he serves, or in the case of the superior court department or Boston municipal court department by the administrative justice therefor. Said first justice or administrative justice may place such restrictions on such authorization as is conducive to the effective administration of justice.
Mass. Gen. Laws ch. 221, § 62B