Massachusetts General Laws Part IV. Crimes, Punishments and Proceedings in Criminal Cases (Ch. 263-280) Ch. 263A, § 4

If a prosecuting officer determines that exigent circumstances exist regarding an imminent threat to the safety of a critical witness, he may take any appropriate temporary action he determines is necessary to protect the safety of the witness without prior approval of the board. The prosecuting officer shall inform the board of the action taken and the related costs within 48 hours. Any such costs, which would otherwise be in compliance with the rules and regulations established by the board pursuant to section 2, may be reimbursed to the prosecuting officer.