Negotiable Instruments Law
Section 64. Liability of irregular indorser.- Where a person, not otherwise a party to an instrument, places thereon his signature in blank before delivery, he is liable as indorsee in accordance with the following rules:
(a) If the instrument is payable to the order of a third person, he is liable to the payee and to all subsequent parties.
(b) If the instrument is payable to the order of the maker or drawer, or is payable to bearer, he is liable to all parties subsequent to the maker or drawer.
(c) If he signs for the accommodation of the payee, he is liable to all parties subsequent to the payee.