Mass. Gen. Laws ch. 43B § 18
Any city or town having a charter under chapter forty-three or forty-three A or a method of electing officers under chapter fifty-four A may change the same in accordance with the procedures for the adoption or amendment of a charter prescribed by this chapter. Except as may be permitted by any general or special law enacted after November eighth, nineteen hundred and sixty-six, no city or town shall adopt or change charters or change its method of electing officers under said chapters forty-three, forty-three A or fifty-four A or under any special laws in effect on such date, including without limitation chapters four hundred and fifty-two of the acts of nineteen hundred and forty-eight, six hundred and sixty-one of the acts of nineteen hundred and forty-nine and one hundred and fifty-two of the acts of nineteen hundred and fifty-four, as amended, and the procedures set forth in this chapter shall be exclusive.
Mass. Gen. Laws ch. 43B, § 18