Mass. Gen. Laws ch. 3, § 51

The committees on rules of the senate and house of representatives shall each appoint a skilled person to act as counsel to the senate and house of representatives, respectively, at such compensation as the said committees may approve. The persons so appointed shall serve for the term of two years from the date of appointment, subject to the pleasure of the said committees. They shall, under the direction of the said committees, after each regular session prepare a table of changes in the general statutes, an index to the acts and resolves, and shall from time to time, under the direction of the said committees or of the general court, consolidate and incorporate in the General Laws all new general statutes. They shall, from time to time, under like direction, make such additions and revisions in the index of the General Laws as may be necessary to insure its prompt publication in connection with future revisions of the statutes. The said committees may direct that copies of the index containing such additions and revisions be deposited, from time to time, in the office of the state secretary or elsewhere and made available for public use.