Cheating on a spouse is emotionally devastating. But is it actually illegal? The answer is more complicated — and more interesting — than most people expect. Depending on where you live, adultery can carry genuine legal consequences, both inside and outside the courtroom.
Adultery Laws: Still on the Books in Many States
Here’s something that surprises a lot of people: adultery is still technically a crime in more than 20 U.S. states. In some, it’s classified as a misdemeanor. In others — like Michigan, for instance — it’s historically been on the books as a felony, though prosecution is exceedingly rare in modern times.
That said, you’re not going to see someone arrested for cheating on their spouse in most of today’s America. Enforcement of these laws is virtually nonexistent. But the fact that they exist at all still matters — especially when it comes to divorce proceedings.
How Adultery Affects Divorce in Fault-Based States
Not all divorces are created equal. Some states are “no-fault” only — meaning the courts don’t care who did what; you can simply cite “irreconcilable differences” and move on. But several states still allow — or even require — couples to declare fault-based grounds for divorce, and adultery is one of the most common.
In fault-based divorce states, proving adultery can influence:
- Property division: Courts may award a larger share of marital assets to the betrayed spouse.
- Alimony: A spouse who committed adultery may be denied spousal support, or required to pay more.
- Divorce proceedings: Establishing fault can sometimes speed up or complicate the legal process.
What About Child Custody?
This is where the stakes really rise. Courts in the U.S. prioritize the best interests of the child in custody decisions. While adultery alone rarely affects custody directly, the circumstances around it can. If a parent’s romantic relationships expose children to instability, conflict, or inappropriate situations, that can absolutely factor into a judge’s decision.
For example, moving a new partner in quickly, exposing children to volatile arguments, or neglecting parental duties due to a new relationship — those behaviors carry more weight than the affair itself.
Proving Adultery Is Harder Than You Think
If you’re in a fault-based state and want to cite adultery in your divorce, you’ll need actual evidence — not just suspicion. Courts typically require proof of both opportunity and inclination. Text messages, emails, hotel receipts, witness testimony, or private investigator reports have all been used as evidence in divorce cases.
Keep in mind: how you gather that evidence matters. Illegally accessing a spouse’s phone, email, or accounts can backfire legally and hurt your credibility in court.
No-Fault States: A Different Story
In states like California, New York (which added no-fault grounds in 2010), and many others, adultery has little to no impact on the legal outcome of a divorce. Property is divided equitably regardless of who was unfaithful, and alimony is based on financial need and earning capacity — not moral behavior.
The Emotional vs. Legal Reality
The pain of being cheated on is real, and wanting accountability is understandable. But the legal system isn’t always the place where that accountability shows up. In many states, the courts simply don’t weigh infidelity heavily — or at all.
If you’re navigating a divorce involving infidelity, talk to a divorce attorney in your state early on. Understanding how your local laws handle adultery will help you set realistic expectations and make smarter decisions throughout the process.
