Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 98, § 18

All cans or containers sold for use in the purchase or sale of milk or cream at wholesale shall have their capacity plainly, conspicuously and indelibly marked thereon in terms of liquid quarts. They shall be sealed by the manufacturer thereof, as hereinafter provided, or by a sealer of the town where the user resides or has a usual place of business. The deputy director shall prescribe regulations governing the sealing of such cans or containers by the manufacturer and may authorize such sealing by any manufacturer upon his agreement to conform to said regulations. The deputy director may at any time, for cause, revoke the authority so given by him to any manufacturer. When sealed by the manufacturer, such cans or containers shall be marked with his name, initials or trade mark and with any other designating marks which the deputy director may require. The sealing of such containers by the manufacturer shall not exempt the user from the laws relative to giving a false or insufficient measure, using a false measure, or having the same in possession with intent to use. Sealers of the town where the user resides or has a usual place of business shall at least annually inspect all cans or containers marked and sealed in accordance with this section and shall make a record of such inspections. When once sealed as herein required, a can or container need not again be sealed while in the same condition as when first sealed.