Massachusetts Criminal Procedure Rule 16: Dismissal by the Prosecution
(Applicable to District Court and Superior Court)
(a) Entry of a Nolle Prosequi. A prosecuting attorney may enter a nolle prosequi of pending charges at any time prior to the pronouncement of sentence. A nolle prosequi shall be accompanied by a written statement, signed by the prosecuting attorney, setting forth the reasons for that disposition.
(b) Entry of a Nolle Prosequi During Trial. After jeopardy attaches, a nolle prosequi entered without the consent of the defendant shall have the effect of an acquittal of the charges contained in the nolle prosequi.