Do Infidelity Clauses in Prenups Actually Hold Up in Court?

Are Infidelity Clauses Enforceable in a Prenup?

Enforceability depends entirely on your state's divorce laws and how the clause is drafted, and most no-fault states refuse to enforce them. There is no federal law governing prenuptial agreements, so outcomes vary dramatically from one jurisdiction to the next.

The leading case is Diosdado v. Diosdado, 97 Cal.App.4th 470 (2002), in which a California appellate court voided a $50,000 penalty triggered by adultery. The court concluded that a contract imposing financial consequences for sexual infidelity contradicts the public policy embedded in California's no-fault divorce statute (Cal. Fam. Code § 2335). Hawaii's highest court later reached the same conclusion in Crofford v. Adachi, 150 Haw. 518 (2022), where a postnuptial agreement required a husband to forfeit the marital yacht if he had another "extramarital event."

On the other side, Pennsylvania and Texas courts have been more receptive to these provisions because both states still permit fault-based divorce filings. But "more receptive" does not mean automatic. Even in fault-permitting states, a judge can reject a clause that looks unreasonable, was signed under pressure, or imposes a disproportionate penalty.

New York sits somewhere in the middle. Some judges have enforced narrow financial provisions triggered by infidelity; others have rejected them as contrary to public policy. The state decriminalized adultery on November 22, 2024, when Governor Kathy Hochul signed a bill removing a rarely enforced 1907 statute that had classified adultery as a class B misdemeanor. That decriminalization hasn't clarified the prenup question.

The concrete risk to understand: an aggressive cheating clause doesn't just risk being thrown out on its own. It can invite a court to scrutinize the rest of an otherwise enforceable agreement more skeptically, potentially jeopardizing financial terms you actually need.

What Is a Prenup Cheating Clause and How Is It Different from Other Lifestyle Clauses?

A cheating clause (also called an infidelity clause or adultery clause) is a prenup provision that imposes a specific financial consequence if one spouse engages in extramarital conduct during the marriage. It's one of the most talked-about prenup topics but also one of the most frequently unenforceable.

Typical forms include:

• Lump-sum payment: The unfaithful spouse pays the other a predetermined dollar amount (commonly ranging from $50,000 to $500,000 or more).
• Larger asset share: The faithful spouse receives a greater percentage of marital property in any future division.
• Spousal support forfeiture: The unfaithful spouse automatically loses the right to alimony or maintenance.

Infidelity clauses fall under a broader category called lifestyle clauses, provisions that reach beyond the three traditional pillars of a prenuptial agreement: property classification and division, spousal support, and estate rights. Other lifestyle clauses might address religion, weight, in-law visit frequency, spending limits, or social media conduct. Courts generally view infidelity clauses as "misconduct clauses" designed to punish one party for perceived wrongdoing during the marriage, which is a distinction that matters when a judge decides whether to enforce them.

Infidelity provisions also appear in postnuptial agreements, often after a known affair. In that context, both spouses are agreeing to remain married with clear financial consequences for future misconduct. Postnup infidelity clauses can face different enforcement patterns because they're signed during an existing marriage, which can raise additional questions about voluntariness and the circumstances of signing.

Which States Enforce Infidelity Clauses and Which Don't?

The table below summarizes how courts in several notable states have treated infidelity clauses based on available case law and statutory frameworks. Keep in mind that limited case law exists in many states, so the absence of a ruling doesn't mean a clause will or won't hold up.

Roughly a third of states are exclusively no-fault, and these are the jurisdictions where infidelity clauses face the steepest resistance. The remaining states offer no-fault divorce but also permit fault-based filings, including adultery as a ground. In those states, courts are generally more open to the argument that an infidelity clause doesn't violate public policy since the legislature already allows fault to play a role. But even in fault-permitting states, a judge still evaluates whether the clause was reasonable at the time of signing and whether it was entered voluntarily.

Colorado's version of the Uniform Premarital and Marital Agreements Act (C.R.S. 14-2-310(2)) provides a useful example of a statutory bar. The statute prohibits any prenup term that attempts to modify the legal grounds for divorce, which means misconduct clauses very likely fail there regardless of how carefully they're drafted.

Why Do Courts Reject Infidelity Penalties Under No-Fault Divorce Law?

Courts reject these clauses primarily because they reintroduce marital fault into a system the legislature designed to keep it out. No-fault divorce allows a couple to end a marriage without proving that either spouse did something wrong. A financial penalty for cheating forces a judge to do exactly what no-fault law says they shouldn't: decide who behaved worse.

Two legal doctrines create the most trouble for infidelity provisions:

1. No-fault public policy. In exclusively no-fault states, appellate courts have held that penalizing a spouse for adultery contradicts the legislature's decision to remove fault from divorce proceedings. California made this reasoning explicit in Diosdado, and Hawaii followed suit in Crofford. The logic is straightforward: a private contract cannot do what the divorce statute forbids.

2. The rule against contractual penalties. Even where public policy isn't the obstacle, courts apply standard contract principles. A financial consequence for infidelity functions as a liquidated damages provision, and courts will reject it if the amount is disproportionate to any actual harm or if the clause is designed more to punish than to reasonably estimate damages. If a clause looks like a penalty rather than a genuine pre-estimate of loss, a court can strike it.

Beyond those doctrines, there's a practical issue: proving infidelity turns a clean financial contract into a litigated question of fact. Instead of dividing assets according to clear, pre-agreed terms, both sides now argue over whether an affair occurred, what counts as "infidelity" under the clause's definition, and when it happened. This injects a new litigable issue into proceedings that the prenup was supposed to simplify.

The Uniform Premarital Agreement Act, adopted by roughly 29 states and the District of Columbia, provides the common framework courts apply. The UPAA allows couples to agree on "any other matter, including their personal rights and obligations," as long as terms don't violate public policy or criminal law. That "public policy" carve-out is where most infidelity clauses fail.

Finally, there's spillover risk. If a court views an infidelity clause as improper, it may look at the rest of the agreement more skeptically. In California, including one can cause a court to scrutinize the entire agreement more carefully, potentially undermining property and support provisions that would have been enforceable on their own.

What Will and Won't a Court Enforce for Lifestyle and Social Media Clauses?

Courts generally distinguish between clear, measurable, financially framed terms and vague behavior mandates that are hard to define or prove. Clauses tied to objective, verifiable events tend to fare better than clauses tied to subjective conduct.

A social media clause restricting posts about the relationship is more likely to be treated as a confidentiality term than a misconduct penalty. That reframing matters because confidentiality provisions have a longer track record of enforcement in contract law generally. Still, enforcement varies by state, and a court may refuse to impose a financial penalty for a social media post if the penalty seems disproportionate or punitive.

Other lifestyle clauses face similar hurdles:

• Weight clauses: Extremely difficult to enforce. Defining what constitutes a violation, who measures it, and when the measurement happens creates ambiguity that courts dislike.
• Drug-testing clauses: Potentially more enforceable if tied to an objective test result, but the provision still needs to be reasonable and not impose a disproportionate penalty.
• Spending-limit or debt-disclosure clauses: Generally on stronger ground because they're tied to verifiable financial behavior, which sits closer to the traditional financial purpose of a prenup.
• In-law visit frequency, religion, number of children: Family law attorneys report seeing all sorts of provisions in this category. Courts are unlikely to enforce most of them because they involve deeply personal decisions that public policy typically leaves to the individuals.

The key principle is that "lifestyle clause enforceability" is decided case by case, not by a single national standard. A clause that works in one state may be void in another. And in every state, a vague provision invites litigation over whether the threshold was actually met, which defeats one of the core purposes of a prenup: clean, predictable financial separation.

How Should Couples Approach Infidelity and Lifestyle Provisions When Drafting a Prenup?

Start with a conversation about what each of you actually wants the agreement to accomplish. If the goal is financial clarity and predictability in the event of divorce, well-drafted property and support terms may get you there more reliably than a contested infidelity clause that a court might reject.

Here are some practical considerations:

• Focus on enforceability over symbolism. The strongest prenup is one where every clause can hold up. Including a provision that courts in your state routinely reject introduces unnecessary risk to the terms you actually need.
• Be specific if you include lifestyle terms. Courts respond better to narrowly drafted provisions with clear definitions than to broad, vague behavior mandates. If you include any lifestyle clause, define the triggering event precisely and attach a financial consequence that looks like a reasonable estimate of impact rather than a punishment.
• Understand your state's rules. Whether you live in a no-fault or fault-permitting state changes the entire analysis. A clause that might survive in Pennsylvania could be void in California.
• Get independent legal review. Each spouse should have their own attorney review any lifestyle or misconduct provision. State law varies enough that general advice is no substitute for state-specific guidance from a qualified family law attorney.

Neptune offers a lawyer-led online prenup where each partner works with their own independent attorney. That structure means both spouses can get candid advice about what's enforceable in their state, including whether a lifestyle provision is worth the risk. If you're considering a cheating clause, discussing state-specific enforceability with your attorney before finalizing the agreement is the most practical step you can take.