Cheating on a spouse is technically a crime in roughly a dozen states, but civilian prosecutors essentially never bring charges. The real question of whether cheating is a crime matters most in four other places: a military court-martial, a divorce case, a citizenship application, and in a handful of states, a civil lawsuit filed by the betrayed spouse against the affair partner.
States That Still Criminalize Adultery
Adultery remains on the criminal statute books in about a dozen states. Most classify it as a misdemeanor. Three treat it as a felony: Michigan punishes adultery as a felony under its criminal code,1Michigan Legislature. Michigan Compiled Laws 750.30 – Adultery; Punishment Oklahoma classifies it as a felony carrying up to five years in prison and a $500 fine,2Justia Law. Oklahoma Statutes Title 21-872 – Punishment for Adultery and Wisconsin treats both the married person and their partner as guilty of a Class I felony.3Wisconsin State Legislature. Wisconsin Statutes 944.16 – Adultery
Prosecutions under these laws are essentially nonexistent, and the trend runs the other direction. New York abolished its adultery crime in 2024, joining the majority of states that have already scrapped these statutes. The Supreme Court’s 2003 decision in Lawrence v. Texas held that private consensual intimate conduct is protected by the Fourteenth Amendment’s due process clause, and while the Court did not directly strike down adultery statutes, any prosecution now faces a serious constitutional challenge. District attorneys have noticed. If you are a civilian and your fear is handcuffs, that fear is almost entirely theoretical.
The Military Is the Real Exception
If you serve in the U.S. armed forces, adultery charges carry actual weight. Under Article 134 of the Uniform Code of Military Justice, adultery is a prosecutable offense,4Office of the Law Revision Counsel. 10 USC 934 Art. 134 General Article and a conviction at court-martial can bring a dishonorable discharge, forfeiture of all pay and allowances, and up to one year of confinement.
Prosecutors must prove three things: that the service member had sexual intercourse with someone, that either the service member or their partner was married to someone else at the time, and that the conduct was prejudicial to good order and discipline or brought discredit upon the armed forces.5United States Army. Legal Separation, Adultery and the UCMJ That third element does most of the work. An affair between a commanding officer and a subordinate’s spouse almost always clears the bar; a discreet relationship with no visible impact on the unit may not.
How Cheating Affects a Divorce
For most people, the legal cost of cheating shows up in family court, not criminal court. Every state offers no-fault divorce, so a cheating spouse cannot block the end of the marriage. But many states also allow fault-based divorce with adultery as a recognized ground, and choosing that route can shift the money.
Alimony
In states that permit fault-based divorce, proven adultery can affect spousal support. Some states allow a judge to reduce or eliminate alimony for the cheating spouse. Others let the court increase the award to the faithful one. A few treat adultery as an outright bar to receiving alimony, while others treat it as one factor among many. In states that only allow no-fault divorce, an affair generally has no effect on support.
Dissipation of Marital Assets
Money a spouse spent on an affair is often recoverable through a doctrine family lawyers call dissipation. Think gifts, travel, rent on a second apartment, or restaurant tabs for someone outside the marriage during the breakdown of the relationship. The non-cheating spouse usually has to prove the spending with clear and convincing evidence, typically through bank and credit card records.
The remedy is not a fine for the affair. The judge adjusts the property split to reimburse the marital estate for what was drained. If one spouse spent $40,000 on a secret apartment for a partner, the other spouse might receive an extra $40,000 in the asset division to even things out. Courts work in dollars, not morality.
Child Custody
Custody turns on the child’s best interests, and a parent’s affair is usually irrelevant to that analysis. Judges weigh parenting ability, not fidelity. An affair becomes a factor only when it directly harms the child, through neglect, exposure to inappropriate situations, or demonstrable emotional damage. On its own, an affair rarely changes custody or visitation.
Suing the Affair Partner
A small group of states still lets the betrayed spouse sue the other person for money damages. These claims, historically called heart balm torts, survive in Hawaii, Mississippi, New Mexico, North Carolina, South Dakota, and Utah, among a few others. Most states abolished them long ago.
Two causes of action are the main ones. Alienation of affection requires the plaintiff to show that genuine love existed in the marriage and that the third party deliberately destroyed it. Criminal conversation is narrower and simpler: it requires proof that the defendant had sexual intercourse with the plaintiff’s spouse during the marriage. You do not need to prove the marriage was happy or that the affair caused its collapse. North Carolina in particular has produced multi-million-dollar verdicts in alienation of affection cases, which is why these lawsuits still draw attention.
Infidelity Clauses in Prenups
Some couples try to put a price on cheating in advance through an infidelity clause in a prenuptial or postnuptial agreement. These provisions attach a financial penalty to adultery, such as a lump sum payment, a shifted asset division, or a spousal support obligation that would not otherwise exist.
Enforceability is unsettled. Some courts have refused to enforce these clauses on public policy grounds. The general pattern: in states where adultery is already a recognized ground for divorce or a factor in alimony, infidelity clauses tend to fare better because state law already penalizes the same behavior. In pure no-fault states, courts are more likely to view the clause as an attempt to reintroduce fault that the legislature deliberately removed. Either way, the clause often triggers expensive litigation.
Immigration and Citizenship
Cheating can quietly derail a naturalization application. Applicants for U.S. citizenship must show “good moral character” during the statutory period before filing, and federal immigration policy treats an extramarital affair that tended to destroy an existing marriage as a conditional bar to establishing it.6USCIS. USCIS Policy Manual Volume 12 Part F Chapter 5 – Conditional Bars for Acts in Statutory Period The applicant can overcome the bar by showing extenuating circumstances, such as a mutual separation with no realistic path to divorce. Without that kind of explanation, an admitted affair during the statutory window can delay or sink the application.