Massachusetts Constitution Amendments Art. II, § 8

The general court shall have the power to act in relation to cities and towns, but only by general laws which apply alike to all cities, or to all towns, or to all cities and towns, or to a class of not fewer than two, and by special laws enacted (1) on petition filed or approved by the voters of a city or town, or the mayor and city council, or other legislative body, of a city, or the town meeting of a town, with respect to a law relating to that city or town; (2) by a two-thirds vote of each branch of the general court following a recommendation by the governor; (3) to erect and constitute metropolitan or regional entities, embracing any two or more cities or towns or cities and towns, or established with other than existing city or town boundaries, for any general or special public purpose or purposes, and to grant to these entities such powers, privileges and immunities as the general court shall deem necessary or expedient for the regulation and government thereof; or (4) solely for the incorporation or dissolution of cities or towns as corporate entities, alteration of city or town boundaries, and merger or consolidation of cities and towns, or any of these matters.

Subject to the foregoing requirements, the general court may provide optional plans of city or town organization and government under which an optional plan may be adopted or abandoned by majority vote of the voters of the city or town voting thereon at a city or town election; provided, that no town of fewer than twelve thousand inhabitants may be authorized to adopt a city form of government, and no town of fewer than six thousand inhabitants may be authorized to adopt a form of town government providing for a town meeting limited to such inhabitants of the town as may be elected to meet, deliberate, act and vote in the exercise of the corporate powers of the town.

This section shall apply to every city and town whether or not it has adopted a charter pursuant to section three.