What Makes a Prenup Unenforceable?

A prenuptial agreement that both people signed can still be thrown out by a Washington court, and it usually happens for reasons that have nothing to do with the signatures and everything to do with fairness. Understanding how a prenup fails is the best way to make sure yours does not. This topic is part of Washington prenuptial and postnuptial agreements.

Signing Is Not the Same as Enforceable

Many couples assume that once a prenup is signed and notarized, it is locked in. That is not how Washington law works. Because Washington has no statute specifically governing prenuptial agreements, their enforceability is decided under case law, and the courts have made clear that they will refuse to enforce an agreement that was unfair in its terms or unfairly obtained. The two decisions that frame this analysis are In re Marriage of Matson, 107 Wn.2d 479, 730 P.2d 668 (1986), and In re Marriage of Bernard, 165 Wn.2d 895, 214 P.3d 132 (2009). Together they explain exactly how a prenup can come apart. Related guides cover Can Prenups Be Challenged in Court? and Can a Prenup Be Modified After Marriage?.

The Test a Court Applies

Under Matson, and as reaffirmed in Bernard, a court evaluates a prenup using a two-prong analysis, with the spouse seeking to enforce the agreement bearing the burden of proof. First, the court asks whether the agreement is substantively fair, meaning whether it makes a reasonable provision for the spouse who is not trying to enforce it. If the agreement is substantively fair, it stands, and the inquiry is over. If the agreement is substantively unfair to that spouse, the court moves to the second prong and examines the fairness of the process, asking whether there was full disclosure of each spouse's property and whether the agreement was freely entered into on independent advice of counsel with full knowledge of each spouse's rights.

A prenup becomes unenforceable when it is substantively unfair and the process that produced it was also flawed. In other words, an unbalanced agreement can survive if it was made the right way, but an unbalanced agreement made the wrong way will fail. Understanding the specific ways the process can break down is where the real lessons lie.

Failure to Disclose Finances

One of the most common ways a prenup fails is a lack of full financial disclosure. The second prong of the Matson test asks whether the spouses disclosed the amount, character, and value of the property involved. If one spouse hid assets, understated their wealth, or simply never provided a complete picture, the other spouse could not have knowingly agreed to give anything up. The Bernard case underscores how seriously courts take this: the Washington Supreme Court held the agreement there unenforceable because it was both substantively and procedurally unfair. A spouse cannot make an informed decision to waive property rights without knowing what is actually on the table, and courts will not pretend otherwise.

No Meaningful Chance for Independent Counsel

The second question under the process prong is whether the agreement was entered into freely, on independent advice of counsel, with full knowledge of each spouse's rights. This is not satisfied by simply telling the other person to go find a lawyer. In Bernard, the wife was repeatedly told to get independent counsel, but she was not given a draft of the agreement she could actually review, and by the time her attorney received a working draft it was substantially different and arrived only days before the wedding. Her lawyer testified he had time only to hit the high points, not to conduct a full review or draft a counterproposal. The court found the process unfair despite the presence of an attorney. The lesson is clear: the opportunity for independent legal advice has to be real and meaningful, not a formality checked off at the last minute.

Coercion and Last-Minute Pressure

Timing and pressure can independently undermine a prenup. When one spouse presents the agreement on the eve of the wedding, with guests arriving and a ceremony already paid for, the other spouse faces a brutal choice between signing and the humiliation of calling off the wedding. Bernard illustrates this vividly. The wife signed the day before a wedding attended by roughly 200 guests, and the husband testified he would have called off the wedding, even the day of, had she not signed. The trial court found she was effectively forced to choose between calling off the wedding and signing a substantively unfair document. That kind of pressure is the opposite of a freely entered agreement, and it is fatal to enforceability.

This is why the calendar matters so much. An agreement negotiated well in advance, with time for each side to review, consult counsel, and negotiate changes, is far stronger than one sprung on a partner in the final days before the ceremony.

Attempts to Cover Off-Limits Subjects

A prenup can also fail, at least in part, when it tries to decide things it legally cannot. Provisions attempting to predetermine child custody or waive child support will not be enforced, because those matters are decided on the best interests of the child at the time the issue arises, not by a contract signed before the children exist. While an improper child provision does not necessarily doom every other term, it signals an agreement that overreached, and it will not bind a court.

A Snohomish County Perspective

In Snohomish County family law, challenges to prenuptial agreements almost always trace back to the same handful of problems: incomplete disclosure, no genuine opportunity for independent advice, and pressure applied too close to the wedding. Couples who avoid those pitfalls, by disclosing everything, giving both partners real time with their own lawyers, and finishing the agreement well before the wedding, end up with something that actually protects them. The couples who cut corners often discover, years later, that the document they relied on offers no protection at all.

Protecting the Agreement You Sign

A prenup becomes unenforceable in Washington when it is substantively unfair and was obtained through incomplete disclosure, a hollow opportunity for counsel, or coercive last-minute pressure, as the Matson and Bernard decisions make plain. The good news is that every one of those failures is avoidable with honesty, time, and independent advice on both sides. The Law Office of Chad Foster helps couples in Snohomish County prepare prenuptial agreements built to withstand a challenge, and helps clients evaluate agreements they have been asked to sign. We would be glad to talk through your situation.

This article is for general informational purposes only and does not constitute legal advice. For guidance on your specific circumstances, please consult a qualified attorney.