When used as a noun, it refers to a person having a duty created by his or her undertaking to act primarily for another's benefit in matters connected with the undertaking. This term can be used both as a noun and as an adjective. _____ Express Authority. Fiduciary is at the heart of agency law. Principal grant certain powers or authority to agents Learn with flashcards, games, and more — for free. Principal-Agent Theory and the EU: Evaluating a Changing Relationship BY Michael Shelton Submitted to the graduate degree program in the Department of Political Science and the Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Master of Arts. . The strongest form of authority is that which is expressly granted, often in written form. The principal consents to the agent’s actions, and the third party may then rely on the document attesting to the agent’s authority to deal on behalf of the principal.