N.Y. UCC Law § 3-307

Section 3--307. Burden of Establishing Signatures, Defenses and Due\n Course.\n (1) Unless specifically denied in the pleadings each signature on an\ninstrument is admitted. When the effectiveness of a signature is put in\nissue\n (a) the burden of establishing it is on the party claiming under\n the signature; but\n (b) the signature is presumed to be genuine or authorized except\n where the action is to enforce the obligation of a purported\n signer who has died or become incompetent before proof is\n required.\n (2) When signatures are admitted or established, production of the\ninstrument entitles a holder to recover on it unless the defendant\nestablishes a defense.\n (3) After it is shown that a defense exists a person claiming the\nrights of a holder in due course has the burden of establishing that he\nor some person under whom he claims is in all respects a holder in due\ncourse.\n