Mass. Gen. Laws ch. 218 § 6
In each district court, as provided in section one, one appointment of associate justice of the trial court shall be made; except that the courts corresponding to the district court of Brockton, the district court of Chicopee, the district court of Chelsea, the first district court of Barnstable, the second district court of Bristol, the third district court of Bristol, the district court of Hampshire, the first district court of eastern Middlesex and the first district court of southern Middlesex, so-called, shall have two justices each; the courts corresponding to the third district court of eastern Middlesex and the central district court of Worcester, so-called, shall have three justices each; and the district court of Springfield shall have four justices.
Except as provided by section two of chapter one thousand and ninety of the acts of nineteen hundred and seventy-one, of section two of chapter three hundred and fifty-six of the acts of nineteen hundred and seventy-three, of section two of chapter nine hundred and fifty-nine of the acts of nineteen hundred and seventy-three, and of section two of chapter five hundred and twenty-two of the acts of nineteen hundred and seventy-six, there shall be appointed in each court an additional number of justices equivalent to the number of justices provided for said court in the first paragraph, which additional number shall correspond to the number of special justices authorized on January thirty-first, nineteen hundred and seventy-six for a district court having substantially the same territorial jurisdiction as said court; provided that in no event shall the total number of justices and special justices in the district court department hereby exceed 158; and provided further that such appointments made under this paragraph shall be made to those courts where vacancies first occur in the office of special justice after February first, nineteen hundred and seventy-six, and thereafter where vacancies occur in positions authorized under this paragraph.
The chief justice of the district court department shall have the power to appoint the first justice of each of the various courts within the district court department, subject to the approval of the chief justice of the trial court, and to define his duties; provided, however, that appropriate consideration shall be given to seniority, length of service at that particular division, and managerial ability. Each first justice so appointed shall serve as the first justice of that court for a 5 year term and shall be eligible to be reappointed for additional 5 year terms at that particular court. Any first justice may be removed from his position as first justice by the chief justice of the district court department; provided, however, that any such removal is not for arbitrary or capricious reasons.
Citations, orders of notice, writs, executions and all other processes issued by the clerk of the court shall bear the test of the first justice thereof or the chief justice of the department.
A special justice in the district court department or the juvenile court department who does not serve full-time in accordance with the provisions of section six A, section fifty-eight B or fifty-eight C shall be paid by the commonwealth for each day's services at the rate by the day of the salary of a justice of the court where he is assigned.
If a justice is absent on Saturday or absent due to an assignment in another court or department within the trial court, no such deduction shall be made therefor from vacation time or sick leave accumulated. During the calendar year of the taking office of a justice no such deduction shall be made for the absence of the justice on that proportion of thirty days corresponding to the proportion of said calendar year remaining after his taking office as justice, nor in addition for the absence of the justice by reason of illness or physical disability for the said proportion of thirty days.
Subject to the provisions of section forty, the special justices in the district court department shall sit and in addition perform such other duties as special justices in such other courts on such occasions as ordered by the chief justice for the district court department; and in such other departments of the trial court as authorized by law.
Mass. Gen. Laws ch. 218, § 6