N.Y. New York City Civil Court Law § 1804
The court shall conduct hearings upon small claims in such manner as to do substantial justice between the parties according to the rules of substantive law and shall not be bound by statutory provisions or rules of practice, procedure, pleading or evidence, except statutory provisions relating to privileged communications and personal transactions or communications with a decedent or person with a mental illness. An itemized bill or invoice, receipted or marked paid, or two itemized estimates for services or repairs, are admissible in evidence and are prima facie evidence of the reasonable value and necessity of such services and repairs. Disclosure shall be unavailable in small claims procedure except upon order of the court on showing of proper circumstances. In every small claims action, where the claim arises out of the conduct of the defendant's business at the hearing on the matter, the judge or arbitrator shall determine the appropriate state or local licensing or certifying authority and any business or professional association of which the defendant is a member. The provisions of this act and the rules of this court, together with the statutes and rules governing supreme court practice, shall apply to claims brought under this article so far as the same can be made applicable and are not in conflict with the provisions of this article; in case of conflict, the provisions of this article shall control.
N.Y. New York City Civil Court Law § 1804