Mass. Gen. Laws ch. 51 § 54
The governor, with the advice and consent of the council, shall, on the petition of not less than ten qualified voters of a city or town, appoint for a term of one year two supervisors of registration for each place of registration therein, one from each of the two leading political parties. They shall attend all sessions or meetings for registration held at the places for which they are appointed, and either of them may attach to any book or papers there used for purposes of registration any statement touching the truth or fairness of the proceedings which he may deem proper, and may add thereto his signature or other marks for the purpose of identification.
Whoever interferes with, or aids or abets any person in interfering with, any supervisor of registration in the performance of his duty, shall be punished by a fine of not more than one hundred dollars or by imprisonment for not more than one year.
Mass. Gen. Laws ch. 51, § 54