Mass. Gen. Laws ch. 94 § 181
Subject to the variations, tolerances and exemptions provided for by section one hundred and eighty-two, no person shall himself or by his agent or servant sell or offer for sale food in package form unless the net quantity of the contents is plainly and conspicuously marked on the outside of the package in terms of weight, measure or numerical count. No person shall himself or by his agent or servant sell or offer for sale at retail any meat, poultry or edible fish, except soft shell clams and oysters, in package form unless there is plainly and conspicuously marked on the outside of such package the price per pound of the contents and the total sales price. This section shall not apply to off-premise, standard factory-packaged meat, poultry or fish items where the weight and price are the same for each meat, poultry or fish item. The first sentence of this section shall not apply to retail sales of food made from bulk if the quantity is weighed, measured or counted at the time of such sale by the retailer, nor to the sale of milk, cream or buttermilk in glass jars, as provided by section fifteen of chapter ninety-eight.
Any commodity put up or packaged in any manner in advance of sale at retail shall bear on the outside of the package a plain and conspicuous declaration of the identity and the net quantity of the contents. The declaration of identity shall identify such commodity by its common or usual name, description, generic term, or the like, unless such commodity may be easily identified through the wrapper or container. The declaration of quantity shall disclose the net quantity of the commodity. The term "net quantity" as used in this section shall mean the quantity of the commodity in the package, exclusive of wrappers and other material packed with such commodity, except that the declaration of quantity on an aerosol package shall disclose the net quantity of the commodity, including the propellant. The declaration of quantity shall be expressed in terms of such weight, measure or count, or a combination of such weight, measure or count, as are firmly established by general consumer usage and trade custom and convey accurate information relative to the quantity or amount of the commodity. If there is no established consumer usage and trade custom with respect to the terms used in such declaration of quantity, the declaration shall, if the commodity is solely liquid, be in terms of liquid measure; otherwise, in terms of weight, except that if a commodity is packaged in an aerosol container, the commodity, including the propellant, shall be in terms of weight, and if the commodity is cloth or yard goods, the declaration shall be in terms of linear measure.
Any representative authorized by the director of standards and any person authorized under section 34, 35 or 36 of chapter 98, shall enforce this section and sections 182 to 184E, inclusive, except section 184A. Enforcement shall include, but shall not be limited to, conducting inspections and issuing notices of violations as provided in section 29A of said chapter 98.
Mass. Gen. Laws ch. 94, § 181