A fiduciary duty is a legal or ethical relationship of trust between two or more parties. For businesses, a fiduciary often has the responsibility to takes care of money or other funds entrusted to it. This is often one of the highest standards of care at equity or law, and a fiduciary is expected to be extremely loyal to the person to whom he owes the duty (i.e. the principal). Business directors and officers have fiduciary duties (duty of care, duty of loyalty) to the business and often times its constituents. Mortgage brokers, financial planners, business partners, shareholders, real estate agents, and escrow agents often have fiduciary duties as well. Parties can also define and create fiduciary duties by contract.
Breach of a fiduciary duty often occurs when business directors and officers put their personal interests ahead of the business. Breach of fiduciary duty lawsuits involving partnerships often also include the following causes of action: breach of contract (a partner did not do what the partnership agreement required him to do), fraud (a partner misrepresented or concealed important facts), breach of fiduciary duty (a partner betrayed the partnership/company), and accounting (figuring out how much a partner misappropriated or how much damage a partner caused).
In California, a cause of action for breach of fiduciary duty requires 1) a fiduciary duty, 2) breach of the fiduciary duty, 3) proximate cause, and 4) harm or damages. Mosier v. Southern California Physicians Insurance Exchange (1998) 63 Cal.App.4th 1022, 1044. If you believe that a breach of fiduciary duty has caused damage to you or your venture, then you should contact an attorney to discuss your potential claims.