Mass. Gen. Laws ch. 127, § 97B

If a treaty in effect between the United States and a foreign country provides for the transfer or exchange of a prisoner to the country of which said prisoner is a citizen or national, the commissioner may, with the written consent of such prisoner, subject to the approval of the governor, and in accordance with the terms of such treaty, consent to the transfer or exchange of any such prisoner and take any other action necessary to initiate the participation of the commonwealth in such treaty.