Prenuptial agreement provisions that violate public policy are the terms a court will refuse to enforce no matter how clearly the couple agreed to them. The categories are reasonably settled: anything that harms a child, pushes a former spouse onto public benefits, was obtained without fair disclosure or free consent, rewards divorce, requires breaking the law, or tries to govern personal behavior during the marriage. Two model statutes shape how most states handle these limits — the Uniform Premarital Agreement Act (UPAA) and its 2012 successor, the Uniform Premarital and Marital Agreements Act (UPMAA), which tightens the procedural rules further.
Anything That Affects a Child
A prenup cannot decide custody, parenting time, or visitation, and it cannot cut off a child’s right to support. The UPMAA states this directly: a premarital agreement may not define the parties’ custody, parenting time, or visitation rights, and it cannot adversely affect a child’s right to support.1Uniform Law Commission. Premarital and Marital Agreements Act The UPAA carries the same prohibition in Section 3(b).
The reasoning is that child support belongs to the child, not to the parent who would receive the check. Parents cannot bargain it away. A clause that caps support at a low number, waives it, or penalizes a parent for seeking custody will be struck. Judges keep full authority to set and modify support based on the child’s actual needs at the time of divorce.
Clauses about a child’s religious upbringing or education sit in a gray zone. Courts have gone both ways. Some treat them as void for indefiniteness or as improper intrusions into religious freedom; others have enforced them as valid promises, especially where the commitment was central to the decision to marry. The consistent rule is that when a child’s welfare conflicts with the contract, the child’s welfare wins.
Alimony Waivers That Would Force a Spouse Onto Public Assistance
A spouse can waive alimony, and many do. The waiver fails when enforcing it would leave the lower-earning spouse destitute and dependent on government benefits. Under the UPMAA, if eliminating spousal support would make a party eligible for public assistance at the time of separation or divorce, the court can require the wealthier spouse to provide enough support to prevent that outcome.1Uniform Law Commission. Premarital and Marital Agreements Act
The policy behind the rule is simple. Private agreements should not shift the cost of supporting a former spouse onto taxpayers. If one party has the resources and the other would otherwise need welfare, the court rewrites that part of the deal. Courts apply this rule without much hesitation.
Unconscionable Terms and the Problems That Create Them
A grossly one-sided prenup can be thrown out as unconscionable. Under UPAA Section 6, a party challenging the agreement generally has to show that it was unconscionable when signed, that they didn’t receive fair financial disclosure, that they didn’t waive disclosure in writing, and that they had no reasonable way to know about the other party’s finances. These conditions typically have to line up together.
The UPMAA goes further by letting courts refuse to enforce any term that is unconscionable at the time of enforcement, not only at signing.1Uniform Law Commission. Premarital and Marital Agreements Act This matters when circumstances change dramatically. An even split that looked fair while both spouses earned similar incomes can become harsh after one of them leaves the workforce for twenty years to raise children. Which test applies depends on the state’s version of the law.
Two procedural problems do most of the damage to prenups years later: hidden finances and pressured signing.
Incomplete Financial Disclosure
Full financial transparency is the foundation of an enforceable agreement. Each party has to receive a reasonably accurate picture of the other’s assets, debts, and income before signing. Under the UPMAA, that requirement is satisfied by a good-faith description and estimate of the other party’s finances, a separate signed waiver of further disclosure, or genuine prior knowledge of the other party’s financial situation.1Uniform Law Commission. Premarital and Marital Agreements Act
Hiding a bank account, understating a business, or leaving out a significant debt can unravel the whole agreement. When a court finds concealment of material financial information, it treats the prenup as if it were built on fraud. This is one of the most common successful attacks on a prenup, and it catches couples who treat disclosure as a formality.
Pressure, Rushed Signings, and No Lawyer
Consent has to be voluntary. The UPMAA spells out what voluntary looks like: each party needs real access to independent legal counsel, meaning a reasonable amount of time to find a lawyer, get advice, and think about it. If one side has a lawyer and the other does not, the agreement has to include a conspicuous plain-language notice explaining which rights are being waived.1Uniform Law Commission. Premarital and Marital Agreements Act
Timing matters. Handing someone a prenup the night before the wedding, with caterers booked and guests arriving, is the textbook duress scenario. Even in states without a specific waiting period, courts examine how much time the signing party had and whether they were truly free to walk away.
Whether each party needs their own attorney varies. Some states view an agreement as suspect or invalid when a single lawyer represented both sides, on the theory that the parties’ interests are opposed. Others allow joint representation if both parties give informed consent and their goals genuinely align. Separate counsel is the safest route, because shared counsel is one of the easiest procedural attacks to mount years later.
Terms That Reward Divorce
Courts will not enforce clauses that make divorce more attractive than staying married. A massive windfall triggered by dissolution, a lump-sum payout far beyond reasonable support, or escalating payments that spike at a particular anniversary can be struck as contrary to public policy. The concern is that the agreement puts a bounty on the marriage itself.
The UPMAA also bars prenups from prescribing fault grounds for divorce.1Uniform Law Commission. Premarital and Marital Agreements Act Couples cannot invent their own private grounds beyond what state law already provides. The line between a reasonable support arrangement and a divorce incentive is not always obvious, but the question courts ask is whether a reasonable person would read the terms as rewarding dissolution rather than compensating for its consequences.
Clauses Requiring Illegal Acts
Any contract provision requiring someone to break the law is void, and prenups are no exception. A clause that calls for tax evasion, hiding assets from creditors, or any other criminal conduct will not be enforced, and acting on it can expose both parties to criminal liability. The issue rarely appears in litigation because most prenups are drafted by attorneys who know better. It tends to surface in agreements written without legal help, especially where one party has slipped in instructions about concealing income or structuring finances in ways that violate tax law.
Personal Conduct and Lifestyle Clauses
Lifestyle clauses try to regulate behavior during the marriage: weight, chores, frequency of intimacy, social media use, in-law visits. Most courts refuse to enforce them. The UPMAA explicitly prohibits provisions that regulate behavior during marriage, which eliminates lifestyle clauses in states that have adopted it.1Uniform Law Commission. Premarital and Marital Agreements Act
Even without that explicit ban, judges are reluctant to referee a marriage. Whether a spouse gained too much weight or cleaned the kitchen often enough is not the kind of fact courts are built to decide. Clauses attempting to control religious practice or social life face additional resistance because they run into constitutional protections for individual liberty.
Infidelity Clauses
Infidelity clauses impose financial penalties for cheating, and they are the most commonly attempted lifestyle provision. In no-fault divorce states, courts frequently strike them down because they reintroduce fault-based punishment into a system designed to leave fault out. Enforcing the clause asks the court to decide who caused the marriage to fail, which is exactly what no-fault laws were written to avoid. In states that still recognize fault or weigh marital misconduct in property division, these clauses have more traction, but enforcement still requires proving the affair, which drags the court into the invasive fact-finding that lifestyle clauses are criticized for in the first place.
Social Media and Non-Disparagement Clauses
Clauses restricting what a spouse can post or say publicly about the other are more common than they used to be, and their enforceability is unsettled. Most divorce courts will not independently restrict social media use without an agreement between the parties, which gives these clauses some negotiating value during divorce. A clause can specify damages for violations, but whether a judge will actually award those damages varies.
What About Sunset Clauses?
Sunset clauses, which cause the prenup to expire after a set number of years, are not a public policy problem. Courts enforce them as written. The risk is purely practical: if the marriage ends after the expiration date, property division and support will be governed entirely by state default rules, as if no prenuptial agreement ever existed. Divorce rates do not fall to zero after any particular anniversary, and anyone considering a sunset clause should go in with that trade-off in mind.