Unauthorized Completion Law and Legal Definition

Unauthorized completion is a phrase used in commercial law. It is the act of filling missing information in a negotiable instrument which is unauthorized. Filling beyond the authority also amounts to unauthorized completion.

Unauthorized completion can be used as a personal defense. It can be raised against a subsequent holder of a negotiable instrument who does not have rights of holder in due course

When a completion is unauthorized, the rules as to material alteration apply, even though the paper was not delivered by the maker or drawer; but the burden of establishing that any completion is unauthorized is on the party so asserting. [Triffin v. Dillabough, 552 Pa. 550 (Pa. 1998)].