What document authorizes one person to act as another person's agent or attorney-in-fact?

• A. Express authority
• B. Agency by estoppel
• C. Power of attorney
• D. Ratification

Answer: (C)

Power of attorney is the written instrument that authorizes one person to act as another’s agent or attorney-in-fact. It names the agent and specifies the scope of authority, which can be broad or limited and can be durable, continuing even if the principal becomes incapacitated. This is distinct from express authority, which is the general concept of authority granted by the principal and may be evidenced in contracts rather than a standalone document. Agency by estoppel involves third-party reliance on perceived authority created by the principal’s actions, not a formal document of authority. Ratification occurs when the principal approves an act after it has been performed, not the initial grant of authority.