Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 127, § 97A

The commissioner may, with the approval of the appropriate officials of the federal government, transfer any prisoner sentenced to state prison to any available or appropriate correctional institution maintained and supervised by the federal government within the confines of continental United States. The commissioner may, subject to the approval of the governor, enter into reciprocal agreements, contracts or other mutual plans to accomplish such transfers.

Prisoners so removed shall be subject to the terms of their original sentences to the state prison and to the provisions of law governing discharge and parole from the correctional institutions of the commonwealth.