Legal Definitions - unauthorized completion

Unauthorized completion is a term used in commercial law to describe the act of filling in missing information on a negotiable instrument without proper authority or beyond the granted authority. This can be raised as a personal defense against any later holder of the instrument who does not have the rights of a holder in due course.

For example, if someone fills in a blank check with an amount that was not authorized by the account holder, this would be considered unauthorized completion. The account holder can raise this defense against any later holder of the check who is not a holder in due course.