Mass. Gen. Laws ch. 231 § 85N
No member of a professional society or of a duly appointed committee thereof, or a duly appointed member of a committee of a medical staff of a licensed hospital or a health maintenance organization licensed under the provisions of chapter one hundred and seventy-six G shall be liable in a suit for damages as a result of his acts, omissions or proceedings undertaken or performed within the scope of his duties as such committee member, provided that he acts in good faith and in the reasonable belief that based on all of the facts the action or inaction on his part was warranted; nor shall an individual be liable in a suit for damages as a result of acts, omissions or proceedings undertaken or performed within the scope of his duties to a nonprofit corporation, the sole voting member of which is a professional society having as members persons who are licensed to practice medicine; provided, however, that such individual acts in good faith and in the reasonable belief that based on all of the facts the action or inaction on his part was warranted.
For the purposes of this section "professional society" shall mean a society having as members persons who are licensed or admitted to practice in the field of law, medicine, chiropractic, optometry, psychiatry or psychology, dentistry, accounting, engineering, land surveyor, as set forth in section eighty-one D of chapter one hundred and twelve, architecture or social work.
Mass. Gen. Laws ch. 231, § 85N