Mass. Gen. Laws ch. 268 § 14B
Any person who is a victim of a crime upon which an accusatory instrument is based, or is subpoenaed to attend a criminal action as a witness and who notifies his employer of such subpoena prior to the day of his attendance, shall not be subject to discharge or penalty by said employer on account of his absence from employment by reason of such witness service. An employer shall not subject an employee to discharge or penalty or the threat of discharge or penalty on account of the absence of such employee from employment by reason of his attendance as a witness at a criminal action. An employer who violates the provisions of this section shall be punished by a fine of not more than two hundred dollars or by imprisonment for not more than one month, or both such fine and imprisonment.
Mass. Gen. Laws ch. 268, § 14B