Mass. Gen. Laws ch. 31A § 10
Nothing in this chapter shall interfere with the right of certified employee organizations to bargain with the municipality over subjects permitted by chapter one hundred and fifty E; provided, however, that the authority of any municipal agency or its agents to determine selection procedures at both the entry and promotional levels, to conduct and grade merit examinations, to rate candidates based on job-related criteria and establish eligible lists, to make initial appointments or promotions to positions covered by local personnel ordinances or by-laws or any other section of chapter thirty-one which is not subject to bargaining under paragraph (d) of section seven of chapter one hundred and fifty E, prior to the effective date of this chapter, shall not be subject to collective bargaining.
Mass. Gen. Laws ch. 31A, § 10