Mass. Gen. Laws ch. 94 § 7
Except as provided in section eight, bread shall not be manufactured for sale, sold, or offered or exposed for sale otherwise than by weight, and shall be manufactured for sale, sold, or offered or exposed for sale only in units of one pound, one and one half pounds, or multiples of one pound. When multiple loaves are baked, each unit of the loaf shall conform to the weight required by this section. The weights herein specified shall mean net weights not more than twelve hours after baking, or not more than twelve hours after the sale and delivery of such loaves by the manufacturer or by his servant or agent. Such weights shall be determined by the average weight of not less than six loaves; provided, that such average weights shall be determined by the weight of at least twelve loaves whenever such number of loaves is available at the time and place of such weighing; and provided further, that bread found upon any premises occupied for the manufacture of bread for sale, or any bread found in the wagons, trucks, baskets, boxes, or other delivery vehicles or receptacles owned or controlled by the manufacturer of such bread, and being transported or delivered for sale, shall for the purposes of this section be deemed to have been baked within twelve hours unless such bread is marked, designated or segregated as stale bread, under regulations prescribed by the director of standards.
Mass. Gen. Laws ch. 94, § 7