A fiduciary duty is an obligation to act in the best interest of another party. For instance, a corporation's board member has a fiduciary duty to the shareholders, a trustee has a fiduciary duty to the trust's beneficiaries, and an attorney has a fiduciary duty to a client.
A fiduciary obligation exists whenever the relationship with the client involves a special trust, confidence, and reliance on the fiduciary to exercise his discretion or expertise in acting for the client. The fiduciary must knowingly accept that trust and confidence to exercise his expertise and discretion to act on the client's behalf.
When one person does agree to act for another in a fiduciary relationship, the law forbids the fiduciary from acting in any manner adverse or contrary to the interests of the client, or from acting for his own benefit in relation to the subject matter. The client is entitled to the best efforts of the fiduciary on his behalf and the fiduciary must exercise all of the skill, care and diligence at his disposal when acting on behalf of the client. A person acting in a fiduciary capacity is held to a high standard of honesty and full disclosure in regard to the client and must not obtain a personal benefit at the expense of the client.