Mass. Gen. Laws ch. 147 § 56
Every motor-driven implement or machine used for the purpose of cutting grass sold, offered for sale, or held with intent to sell in the commonwealth shall be equipped with a safety device designed and attached by the manufacturer in accordance with the specifications and requirements established by the commissioner of the division of occupational licensure for the purpose of protecting the operator thereof and any other person from objects which may be ejected or propelled from the blade area of such implement or machine. Said commissioner may promulgate such rules and regulations as may be necessary to enforce the provisions of this section. Whoever violates any provisions of this section or of any rule or regulation promulgated hereunder shall be punished by a fine of not more than five hundred dollars for each offense.
Mass. Gen. Laws ch. 147, § 56