Mass. Gen. Laws ch. 121B § 40

(h) A housing authority shall not provide such housing to any person who is a current illegal user of one or more controlled substances as defined in section one of chapter ninety-four C. A person's illegal use of a controlled substance within the preceding twelve months shall create a presumption that such person is a current illegal user of a controlled substance, but the presumption may be overcome by a convincing showing that the person has permanently ceased all illegal use of controlled substances. The prohibition of the provision of housing contained in this subsection shall not apply to housing provided through residential treatment programs for illegal users of controlled substances.