Massachusetts General Laws Part IV. Crimes, Punishments and Proceedings in Criminal Cases (Ch. 263-280) Ch. 263A, § 13

(a) A prosecuting officer may disclose or refuse to disclose the identity or location of a protected witness, or any other matter concerning a protected witness or the program, after balancing the danger such disclosure may pose to the protected witness, the detriment it may cause to the general effectiveness of the program, and the benefit it may afford to the public or the person seeking discovery, except that a prosecuting officer shall, upon the request of a federal, state or local law enforcement official, or pursuant to a court order, disclose to such official the identity, location and criminal records relating to the protected witness when the prosecuting officer knows, or the request from such official indicates, that the protected witness is under criminal investigation for, or has been arrested for, or charged with, a felony.

(b) Whoever, without the express written authorization of the prosecuting officer, knowingly discloses any information received from the prosecuting officer or generated in connection with witness protection services and which poses a risk of harm: to a program participant; of disclosure of any person's participation in such program; or of jeopardizing the objectives of the program shall be punished by imprisonment in the house of correction for not more than 2 1/2 years or by a fine of not more than $5,000, or by both such fine and imprisonment. This section shall not apply to: any members of the board; members of the attorney general's office; members of the district attorneys' offices; law enforcement; or agents thereof, acting in the lawful discharge of their duties.