Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 175, § 111E

With the prior written approval of the commissioner of insurance, a group liability insurance policy may be issued by a company affording professional liability coverage for bodily injury and property damage including wanton and reckless assault and battery, but excluding wilful or intentional assault and battery;  provided, such policy insures the members of an association formed under the authority of chapter one hundred and eighty consisting of at least five hundred members of whom not less than seventy-five per cent are insured thereunder.