Mass. Gen. Laws ch. 40 § 21B
Any town by by-law adopted at an annual town meeting, any city having a Plan D or Plan E charter by ordinance adopted in accordance with the provisions of its charter, and any other city by ordinance approved by its mayor may establish a personnel relations review board and may empower such board to adjust the grievances of all employees of such town or city other than those appointed by the school committee; provided, that such a board, by such an adjustment, shall not involve the city or town in an expenditure of money in excess of the appropriation made for the use of such board. As used in this section, the word "grievance" shall be construed to mean any dispute between an employee of a city or town and his appointing authority arising out of an exercise of administrative discretion by such authority under the contract of employment between the employee and the city or town, except a dispute concerning a change in one or more of the terms of such contract and except also a dispute which is, or upon proper appeal would be, within the jurisdiction of the civil service commission or the contributory retirement appeal board. No ordinance establishing in any city a personnel relations review board required by this section to be approved by the mayor of such city shall be amended except by ordinance likewise approved.
Mass. Gen. Laws ch. 40, § 21B