A fiduciary is a person or legal entity that has the power and responsibility of acting for another in situations requiring total trust, good faith and honesty. Being a fiduciary entails always acting in the client's best interest, even if doing so is contrary to that of the fiduciary. In addition, fiduciaries are required to disclose any potential conflicts of interest to the client, and must strive to work on behalf of clients in a manner that's as efficient and low-cost as possible. The fiduciary standard is the highest standard of care.