Faith must be observed. An agent must not violate the confidence reposed in him.

Explanation

(English-origin maxim.) An agent owes a fiduciary duty of loyalty and good faith to his principal — invoke this to hold an agent liable for breach of trust, self-dealing, or unauthorized disclosure of confidential information.

Where this applies

• A real estate agent secretly buys a property his client wanted, using inside knowledge from the listing; the court holds him liable for breach of fiduciary duty because an agent must not violate the confidence placed in him.
• A financial advisor shares a client's private investment strategy with a competitor; the client sues for breach of trust because the agent's duty of loyalty and good faith was absolute.
• A lawyer discloses privileged information about her client's case to the opposing party; the court disqualifies her and awards sanctions because faith must be observed — an agent must never betray the principal's confidence.