Are Infidelity Clauses Enforceable in a Prenup?

Do Courts Enforce Infidelity Clauses in a Prenup?

Most courts will not enforce an infidelity clause, and the legal trend is moving further against them. There is no federal law governing prenuptial agreements, so whether a cheating penalty survives a court challenge depends entirely on the divorce laws of your state.

In exclusively no-fault states, courts have consistently held that penalizing a spouse for adultery contradicts the legislature's decision to remove fault from divorce proceedings. California's appellate court made this reasoning explicit in Diosdado v. Diosdado, 97 Cal.App.4th 470 (2002), striking down a $50,000 adultery penalty. Hawaii's Supreme Court reached the same conclusion in Crofford v. Adachi, 150 Haw. 518 (2022), voiding a postnuptial clause that required a husband to forfeit the marital yacht after an "extramarital event."

In the minority of states that still permit fault-based divorce grounds, courts are more open to infidelity provisions, but "more open" does not mean "will enforce." Even in Texas and Pennsylvania, judges scrutinize penalty provisions for fairness, and the practical difficulty of proving adultery introduces litigation costs that can dwarf the clause's dollar value.

Perhaps most importantly, including an aggressive infidelity clause can expose your entire prenup to heightened judicial scrutiny. A court that finds one provision unenforceable may look more skeptically at the rest of the agreement, potentially jeopardizing property division and spousal support terms that would have held up on their own.

What Is an Infidelity Clause in a Prenup?

An infidelity clause is a prenuptial provision that attaches a financial consequence to adultery during the marriage. It falls under the broader category of "lifestyle clauses," which attempt to govern behavior rather than the financial pillars a standard prenup typically addresses.

A standard prenuptial agreement covers three core areas: classification and division of property upon divorce, spousal support upon divorce, and estate rights. Infidelity clauses reach beyond those pillars by tying financial outcomes to marital conduct. Common structures include:

• Lump-sum payment: The unfaithful spouse pays a fixed dollar amount to the other spouse if the marriage ends. Celebrity examples make headlines (Jessica Biel reportedly has a $500,000 clause tied to Justin Timberlake's fidelity), but similar provisions appear in everyday agreements.
• Asset forfeiture: The cheating spouse gives up their claim to specific property, such as the family home or a retirement account.
• Spousal support adjustment: The offending spouse either forfeits their right to spousal support or becomes obligated to pay support they otherwise would not owe.

Infidelity clauses sit alongside other lifestyle provisions that courts frequently view with skepticism. Family law attorneys report seeing clauses covering everything from how many football games a spouse can watch to how often in-laws can visit. Courts tend to treat all of these behavioral provisions less favorably than straightforward financial terms.

Definitional precision matters, too. Some couples define infidelity broadly (any romantic or sexual contact outside the marriage), while others limit it to specific physical acts. Vague definitions create additional enforcement problems because courts need clear, provable standards to apply.

Which States Enforce Infidelity Clauses in a Prenup?

The answer breaks down along the no-fault versus fault-permitting divide, though even within those categories, outcomes vary.

California is the clearest rejection. Diosdado held that a contract imposing financial consequences for sexual infidelity is contrary to the public policy embedded in the state's no-fault divorce statute (Cal. Fam. Code § 2335). Including a cheating clause in a California prenup doesn't just mean the clause fails; it can cause a court to scrutinize the entire agreement more skeptically.

Hawaii reinforced California's reasoning in Crofford v. Adachi, finding that agreements contingent on a spouse's misconduct force the family court to evaluate fault in direct conflict with no-fault divorce policy.

Colorado's Uniform Premarital and Marital Agreements Act (C.R.S. 14-2-310(2)) bars any prenup term that attempts to modify the legal grounds for divorce, which is why misconduct clauses very likely fail there as well.

New York presents a murkier picture. Under DRL § 236(B)(3), prenuptial agreements may address maintenance and other terms of the marriage relationship. Some New York judges have enforced narrow financial provisions triggered by infidelity; others have rejected them as against public policy. The state's November 2024 decriminalization of adultery, when Governor Hochul signed the bill removing the class B misdemeanor, adds cultural context but does not resolve the enforceability question. "Maybe enforceable, depending on the judge" is not a strong foundation for a provision you'd need to rely on.

Texas and Pennsylvania are more receptive because they still permit fault-based divorce grounds, which means a judge can already consider adultery when dividing property or awarding support. But even in these states, courts view penalty provisions with skepticism, and the practical challenges of proving infidelity remain significant.

Why Do Courts Reject Infidelity Clauses in Prenups?

Two legal doctrines create the most trouble for infidelity clauses, and a third practical problem makes them even less appealing.

No-fault divorce public policy

Every state now offers some form of no-fault divorce. About a third of states are exclusively no-fault, meaning fault-based grounds like adultery are not available at all. In those jurisdictions, courts have concluded that penalizing a spouse financially for cheating contradicts the legislature's deliberate decision to remove fault from divorce proceedings. A private contract cannot override that public policy choice.

The penalty doctrine

Contract law generally disfavors provisions that function as punishments rather than reasonable pre-estimates of actual damages. An infidelity clause that requires a $500,000 payment when the non-cheating spouse cannot show $500,000 in actual financial harm looks like a penalty. Courts may void the clause on this basis alone, even in states that permit fault-based divorce.

The proof problem

Prenups are supposed to create clean, predictable financial separation. An infidelity clause does the opposite. Proving adultery typically requires testimony, private investigator reports, digital evidence, or depositions, all of which add litigation time and expense. As the ACTEC Foundation has noted, there are very few reported cases on enforcement of adultery penalty provisions, which makes outcomes unpredictable and opens couples up to litigating "something that is very intimate, private, and embarrassing."

The good news is that courts generally still enforce the rest of a prenup if it independently meets standard requirements: voluntary execution by both parties, full financial disclosure, independent legal counsel, and terms that are not unconscionable. The infidelity clause may fail without dragging down your property division and support provisions, though including one does increase the risk of broader scrutiny.

How Should Couples Approach Infidelity Clauses When Drafting a Prenup?

The strongest prenup is one where every clause is enforceable. Before adding an infidelity clause in a prenup, couples benefit from stepping back and discussing what they actually want the agreement to accomplish.

Start with an honest conversation

If fidelity is a core value for both of you, talk about it openly before the drafting process begins. Understand what financial clarity and commitment mean to each of you. As Michael C. Cotugno, Esq., Managing Partner, Neptune Legal, puts it: "A premarital agreement doesn't have to be a wedge between partners or a necessary evil that protects assets at the expense of trust and intimacy."

That conversation may reveal that what you actually want is financial predictability, not a penalty clause. Many couples find that clear property division terms and well-structured spousal support provisions give them the confidence they're looking for without the legal uncertainty of a lifestyle clause.

Get state-specific legal advice

An independent, licensed attorney in your state can tell you whether a proposed infidelity clause is likely to be enforceable or could jeopardize the broader agreement. Independent counsel for each partner is highly recommended for an enforceable prenup. What works (or at least has a chance) in Pennsylvania will almost certainly fail in California, and your attorney needs to advise based on your state's case law and statutes.

Focus on reliably enforceable provisions

Rather than risking the entire agreement on a clause courts routinely reject, consider directing your energy toward the three pillars that courts consistently uphold:

• Property division: Classify which assets remain separate and how marital property will be divided.
• Spousal support: Set terms for maintenance that both parties agree are fair at the time of signing.
• Estate rights: Address inheritance and beneficiary designations so both partners have clarity.

These provisions give you financial predictability regardless of why the marriage might end. They work in every state when properly drafted, and they don't require anyone to prove private behavior in open court.

If you still want an infidelity clause

If you and your partner decide to include one after getting legal advice, keep the financial consequence modest and reasonable rather than punitive. Define infidelity precisely so both parties know exactly what conduct triggers the clause. Frame the provision as a financial adjustment (for example, a modification to spousal support) rather than a lump-sum penalty, since courts are somewhat more receptive to provisions that look like agreed-upon support terms rather than fines. And make sure the rest of your prenup stands on its own so that if the infidelity clause is struck down, your core financial terms survive.