3-406 - Negligence Contributing to Alteration or Unauthorized Signature.
Section 3--406. Negligence Contributing to Alteration or Unauthorized Signature. Any person who by his negligence substantially contributes to a material alteration of the instrument or to the making of an unauthorized signature is precluded from asserting the alteration or lack of authority against a holder in due course or against a drawee or other payor who pays the instrument in good faith and in accordance with the reasonable commercial standards of the drawee's or payor's business.