N.Y. CPL Law § 650.30

§ 650.30 Securing attendance of prisoner in federal institution as\n witness in criminal action in the state.\n 1. When (a) a criminal action is pending in a court of record of this\nstate by reason of the filing therewith of an accusatory instrument, or\na grand jury proceeding has been commenced, and (b) there is reasonable\ncause to believe that a person confined in a federal prison or other\nfederal custody, either within or outside this state, possesses\ninformation material to such criminal action or proceeding, and (c) the\nattendance of such person as a witness in such action or proceeding is\ndesired by a party thereto, a superior court, at a term held in the\ncounty in which such action or proceeding is pending, may issue a\ncertificate, known as a writ of habeas corpus ad testificandum,\naddressed to the attorney general of the United States, certifying all\nsuch facts and requesting the attorney general of the United States to\ncause the attendance of such person as a witness in such court for a\nspecified number of days under custody of a federal public servant.\n 2. Such a certificate may be issued upon application of either the\npeople or a defendant, demonstrating all the facts specified in\nsubdivision one.\n 3. Upon issuing such certificate, the court may deliver it, or cause\nor authorize it to be delivered, to the attorney general of the United\nStates or to his representative authorized to entertain the request.\n