New York Consolidated Laws, Criminal Procedure Law - CPL § 620.50 Material witness order;  hearing, determination and execution of order

(a) The applicant has the burden of proving by a preponderance of the evidence all facts essential to support a material witness order, and any testimony so adduced must be given under oath;

(b) The prospective witness may testify under oath or may make an unsworn statement;

(c) The prospective witness may call witnesses in his behalf, and the court must cause process to be issued for any such witness whom he reasonably wishes to call, and any testimony so adduced must be given under oath;

(d) Upon the hearing, evidence tending to demonstrate that the prospective witness does or does not possess information material to the criminal action in issue, or that he will or will not be amenable or respond to a subpoena at the time his attendance will be sought, is admissible even though it consists of hearsay.

(a) If the bail is posted and approved by the court, the witness must, as provided in subdivision two of section 510.40 of this part, be released and be permitted to remain at liberty;  provided that, where the bail is posted by a person other than the witness himself, he may not be so released except upon his signed written consent thereto;

(b) If the bail is not posted, or if though posted it is not approved by the court, the witness must, as provided in subdivision two of section 510.40 of this part, be committed to the custody of the sheriff.