Section 58B. (a) Any special justice of the Boston juvenile court holding office on January first, nineteen hundred and seventy-six may, in accordance with the provisions of paragraph (c), certify in writing to the justice of the Boston juvenile court that upon said certificate becoming effective, said special justice shall devote full-time during ordinary business hours to the duties of his office and shall not engage directly or indirectly in the practice of law. Said certificate shall become effective at such time as the justice of the Boston juvenile court may direct, but in no case later than July first, nineteen hundred and seventy-nine provided that no such special justice shall become full-time before another who has filed a certificate before him; and provided further that no certificate may be withdrawn after it has been filed.

(b) Upon said certificate becoming effective, said special justice shall be subject to the following provisions: (1) he shall devote full-time during ordinary business hours to the duties of his office, and shall not engage directly or indirectly in the practice of law; (2) he shall be paid the salary provided in section seventy-seven A for justices of the district courts who are required to devote full-time to their duties, other than the chief justice of the district courts, said salary to be paid from the same source and in the same manner as the salary paid to the justice of the Boston juvenile court, and travel and expense allowances to the same extent as is provided for justices of district courts; (3) he shall sit in such other courts in such manner as the law provides for special justices who serve full-time in accordance with the provisions of section six A; provided that when he is assigned to sit in another court it is upon the concurrence of the chief justice of the district courts and the justice of the Boston juvenile court; and (4) he shall have such other powers, duties, rights and privileges as has a special justice under clause (4) of paragraph (b) of section six A.

(c) The certificate provided for in paragraph (a) of this section may be filed with the justice of the Boston juvenile court at any time before May first, nineteen hundred and seventy-nine.

(d) A special justice of the Boston juvenile court who certifies himself in accordance with the provisions of this section shall be deemed to be entitled to the provisions of section six with regard to vacation and sick leave, including the provisions relative to accumulation; and, provided further, that during the calendar year in which his certificate is made effective, said special justice shall be entitled to the number of absences for vacation and sick leave corresponding to the proportion of said year remaining after said certificate becomes effective.

Notwithstanding any provisions of the General Laws to the contrary, (1) for the purposes of determining his pension responsibilities a special justice of the Boston juvenile court who serves full-time in accordance with the provisions of this section shall not be subject to the provisions of section sixty-five D of chapter thirty-two; and (2) for purposes of determining the pension rights of a special justice of the Boston juvenile court who files a certificate in accordance with the provisions of this section said special justice may elect to waive the provisions of section sixty-five B of chapter thirty-two and his full-time service shall be deemed the service of a justice of a district court, other than the chief justice, and said special justice shall be entitled to the same credit for his part-time service, if any, as a special justice as is provided in section sixty-five A of chapter thirty-two for a justice of a district court who has previously served as a special justice, provided, however, that nothing herein shall be construed to alter the pension rights and responsibilities applicable to a special justice of the Boston juvenile court who does not file a certificate under the provisions of this section.

(e) Any special justice of the Boston juvenile court who does not file a certificate under the foregoing provisions shall after July first, nineteen hundred and seventy-nine, be precluded from engaging directly or indirectly in the practice of law.

(f) Except as provided in paragraph (e), nothing in this section shall affect the powers, duties, rights and privileges of any special justice of the Boston juvenile court who is holding his office on January first, nineteen hundred and seventy-six and who does not file a certificate under paragraph (a).

(g) Nothing in this section shall be construed to establish a new judicial position nor to abolish the tenure of any incumbent special justice of the Boston juvenile court.

(h) Nothing in this section shall be construed to interfere with the existing administrative powers and duties of the justice of the Boston juvenile court.