Mass. Gen. Laws ch. 218 § 50
The Boston municipal court department established under section one of chapter two hundred and eleven B shall consist of 30 associate justices of the trial court appointed to said department. They shall devote their entire time during ordinary business hours to their duties and shall not, directly or indirectly, engage in the practice of law. Said justices shall each be entitled to thirty days vacation and thirty days sick leave in each calendar year. Vacation leave and sick leave not used in any such year may be accumulated, provided that the number of vacation days so accumulated shall not exceed sixty and the total amount of sick leave shall not exceed one hundred and eighty days.
The chief justice of the department, subject to the approval of the supreme judicial court and the chief justice of the trial court, may make, from time to time, rules for regulating the practice and conducting the business therein in all cases not expressly provided for by law.
Unless the context refers only to a district court or a juvenile court, or some other clearly contrary intent, whenever the words "municipal court of the city of Boston", "municipal court", "district court" or "court" are used in this chapter, they shall refer to the Boston municipal court department. And unless the context includes, or refers only to, a person appointed to a district court or to the Boston juvenile court, the words "justice" or "associate justice" shall mean an associate justice of the trial court appointed to the Boston municipal court department; and the words "clerk" or "clerk of court" shall mean a clerk of said department; and the words "assistant clerk", "deputy assistant clerk", "temporary clerk" or "temporary assistant clerk" shall mean, respectively, an assistant clerk, deputy assistant clerk, temporary clerk or temporary assistant clerk of said department.
Mass. Gen. Laws ch. 218, § 50