Fiduciary Duty

A legal duty of utmost good faith and full disclosure owed by one party to another. Spouses owe each other a fiduciary duty; engaged couples generally do not.

Married spouses owe each other a fiduciary duty — the highest standard of honesty and care recognized by law. This is one of the main reasons courts apply stricter scrutiny to postnuptial agreements than to prenups. Disclosure must be more thorough; voluntariness is examined more closely; any sign of overreaching by one spouse is taken seriously.

Engaged couples generally do not yet owe each other a fiduciary duty in the formal sense, though some states (Maryland in particular) treat them as being in a "confidential relationship" that imposes similar requirements. Either way, the practical effect is the same: high standards of disclosure and voluntariness apply to prenups too.

Related terms

Postnuptial Agreement — A written contract between spouses, signed after the marriage, that defines what happens to property and support if the marriage ends.
Financial Disclosure — The requirement that each spouse provides a complete and specific accounting of their finances — assets, debts, and income — before signing a prenup.
Overreaching — A spouse's use of their position of confidence or power to extract terms that the other spouse would not have agreed to in a fair negotiation. A common ground for invalidation in confidential-relationship states.

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