Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 138, § 16

Any person holding a license under section twelve, thirteen, fourteen or fifteen who, directly or through any agent, employee or other person, dilutes or changes or in any manner tampers with any alcoholic beverage authorized to be sold under such license so as to change its composition or alcoholic content shall be punished by a fine of not less than two hundred nor more than five hundred dollars, and if any holder of such a license is convicted of a violation of the foregoing, his license shall forthwith be suspended, for a period of not less than six months, by the local licensing authorities which issued the same; provided, that cocktails and other mixed drinks may be prepared on premises licensed under section twelve, thirteen or fourteen.

Possession on the licensed premises by any licensee referred to in this section of any alcoholic beverage differing in composition or alcoholic content from such beverage when received from the manufacturer or wholesaler and importer from whom it was purchased, except cocktails and other mixed drinks as hereinbefore authorized, shall be prima facie evidence that the said beverage has been diluted, changed or tampered with in violation of this section.