Participating in a transaction for one's own personal benefit rather than for the one owed a fiduciary duty; for example, a trustee using property held in trust for her own benefit. Many states have laws prohibiting such action, and there are federal statutes that do so under certain circumstances. adj. self defense Description of actions taken to protect oneself, as in a shooting of a perpetrator by a police officer upon whom the perpetrator has pulled a gun. adj. self-executing That which t...