Mass. Gen. Laws ch. 234A § 1
This chapter shall apply in every county in the commonwealth which has been designated as a participating county as hereinafter provided. Middlesex county shall be a participating county as of the effective date of this chapter. The supreme judicial court shall designate such further participating counties and the dates on which the various sections of this chapter shall become applicable within such participating counties. The supreme judicial court shall make such designations in a manner that will expand the application of this chapter to all counties in an orderly, prudent, and expeditious manner.
Whenever any section of this chapter shall become applicable within a participating county, all provisions of law which are inconsistent with such section shall cease to be effective within such participating county. Hereinafter in this chapter, the word "county" shall mean "participating county" unless specifically stated otherwise.
Mass. Gen. Laws ch. 234A, § 1