Mass. Gen. Laws ch. 90 § 11
Every person operating a motor vehicle shall have the certificate of registration for the vehicle and for the trailer, if any, and his license to operate, upon his person or in the vehicle, in some easily accessible place, except that the certificates of registration of dealers, manufacturers, repairmen, owner-repairmen, farmers or dealers in both boats and boat trailers need not be so carried; provided, however, that the certificate of registration of a person who is operating a motor vehicle in accordance with the provisions of the last sentence of the fifth paragraph of section two need not be so carried; and, provided further, that in the case of a rental vehicle, a photostat copy of the certificate of registration, accompanied by the rental agreement, shall be sufficient to comply with the provisions of this section. If for any reason the registrar or his agents are unable to issue promptly to an applicant the certificate of registration or the license applied for, they may issue a receipt for the fee paid, and said receipt shall be carried in lieu of the certificate or license as the case may be, and for a period of sixty days from the date of its issue said receipt shall have the same force and effect given to the certificate or license by this chapter. If, in compliance with a written demand of the registrar or any of his authorized agents, a certificate of registration or license to operate is returned for inspection or for any other purpose, except for suspension or revocation, such written demand shall be carried in lieu of the certificate or license, as the case may be, and for the period of sixty days from its date said demand shall have the same force and effect given to the certificate or license by this chapter. Any operator who knowingly collides with or causes injury to any person or damage to any property shall, upon the request of the person injured or the person owning or in charge of the property damaged, plainly exhibit to such person his license and, if required under the provisions of this chapter to carry the certificate of registration for the vehicle upon his person or in the vehicle, such certificate.
Mass. Gen. Laws ch. 90, § 11