Casto v. Casto

Florida Supreme Court held that an unequal bargain alone is not grounds to vacate a marital agreement, and laid out the two grounds Florida courts still apply.

Why this case matters

Casto is the framework Florida courts still apply alongside the state's UPAA — particularly for challenges based on alleged unfairness. For Florida prenup drafters, the case is the reason a substantively asymmetric agreement can still be enforced as long as the procedure was clean.

The facts

In Casto, the wife received $225,000 in a marital settlement to waive claims against the husband's estate, which she later alleged was worth roughly $10 million. The lower court set the agreement aside, finding the disparity unconscionable. The Florida Supreme Court reversed.

The holding

The Florida Supreme Court held that an unequal bargain alone is not grounds to set aside a marital agreement. The court identified two grounds for invalidation: (1) fraud, deceit, duress, coercion, misrepresentation, or overreaching; or (2) unreasonableness coupled with non-disclosure. Mere disparity in value — without one of these — is not enough.

What it means for you

• Florida prenups are not invalidated for unequal terms alone.
• A challenger must prove either procedural misconduct OR unreasonableness PLUS non-disclosure.
• Full disclosure remains the most important defense against the "unreasonableness plus" prong.
• Florida's framework is reinforced by §61.079 (the state's UPAA), but Casto remains the touchstone for analysis.

Primary source

The full opinion is available at: https://law.justia.com/cases/florida/supreme-court/1987/66325-0.html

Florida prenup law in context

Florida prenups are governed by Fla. Stat. §61.079 — official statute text. For the full cost breakdown, attorney rate ranges, and procedural requirements, see the Florida prenup cost guide.

To check whether your specific situation has the kind of risks Casto v. Casto identifies, take the 60-second prenup quiz — it applies Florida-specific rules to your answers.

A note on legal citation

This page summarizes a published court opinion for educational purposes. We aim for accuracy but recommend reading the primary source linked above for the controlling text. Court opinions can be modified, distinguished, or overruled by later decisions; for current law, consult a family law attorney licensed in Florida.