Bringing on a lawsuit to set aside the terms of a marital settlement agreement, whether they are in writing or made in open court and the terms are dictated on the record, is an arduous job. Agreements of settlement are normally favored by the courts, and only where there can be shown that the agreement was procured through the fraud of one of the parties, or there is a mistake of fact, or the terms are viewed as unconscionable (that is that they are grossly unfair and no one in their right minds would enter into), can they be set aside. The proof necessary to succeed on such a lawsuit is great.
A mere claim of unconscionability or fraud, without facts to clearly show that that such assertion is true, will not be successful. Duress and breach of fiduciary duty are other grounds that the law recognizes. Where there has been physical coercion to force a party into signing an agreement, this would be one example of proper grounds based on duress. Since husband and wife stand in a fiduciary relationship to one another, where it can be shown that one spouse has withheld financial information from the other which he has a duty to disclose, this could form another basis to set aside the agreement.
These lawsuits are very difficult, and the rate of success is limited. Accordingly, before embarking on such a cause of action, there must be an analysis of the risk to reward ratio before starting.