Cheating on your spouse is painful. It can destroy a family. But is it actually illegal in Washington? That’s where most people get surprised.
The short answer is no. Washington does not treat adultery as a crime. But that doesn’t mean it has zero consequences. Stick with me here, because the details actually matter a lot.
What Is Adultery?
Adultery means a married person has a sexual relationship with someone who is not their spouse. Pretty simple definition. But the legal side of it? A little more layered.
Some states still treat adultery as a criminal offense. Washington is not one of them. In fact, Washington removed adultery from its criminal code all the way back in 1975. That’s right, this has been the law for over 50 years. Most people don’t realize how old that change actually is.
So simple! You cannot be arrested, charged, or prosecuted for having an affair in Washington. It is not a crime here.
Washington’s No-Fault Divorce System
Okay, this part is important. Even though adultery is not a crime, it still shows up in divorce cases. Sort of.
Washington operates under what lawyers call a “no-fault” divorce system. That means you do not need a reason to get divorced. You don’t have to prove your spouse did anything wrong. You just have to say the marriage is “irretrievably broken.” That’s the only legal requirement under RCW 26.09.030.
Wondering why that matters? Because it means cheating is basically irrelevant to the divorce itself. The court does not care who did what. Judges in Washington are actually not allowed to consider marital misconduct when dividing property or deciding on spousal support.
Right? That surprises a lot of people.
Can Adultery Affect Your Divorce Settlement?
Here’s where things get more interesting. Adultery cannot be used as grounds for divorce in Washington. But it can still indirectly affect your case in a specific way.
Hold on, this part is important. If your spouse spent marital money on their affair, that changes things. Courts call this “dissipation of marital assets.” Think of it like theft from the marriage account.
For example, imagine your spouse rented an apartment for their affair partner. Or paid for vacations, gifts, and dinners using shared funds. You can document those expenses and bring them to court. Under RCW 26.09.080, a judge could award you a larger share of remaining property to make up for what was spent on the affair.
You’re not alone if this confuses you. Most people mix up “adultery doesn’t matter” with “money spent on affairs doesn’t matter.” Those are two very different things.
What About Alimony?
Honestly, this is the part most people miss. Many betrayed spouses assume cheating will help them get more spousal support. It usually doesn’t work that way in Washington.
Washington courts look at specific factors when deciding alimony. These include your income, your spouse’s income, how long you were married, your age and health, and your standard of living during the marriage. The affair itself does not get thrown on the scale.
Pretty much, the judge does not want to hear about who cheated. They want to see financial numbers. That’s the reality of a no-fault state.
Does Adultery Affect Child Custody?
A friend asked me about this last week. She assumed her spouse’s affair would automatically give her full custody. It doesn’t work that way. That surprised her.
In Washington, child custody decisions are based on one thing: the best interests of the child. The court wants to know what arrangement is healthiest for the kids. An affair on its own does not change that calculation.
But here is the exception. If the affair involved behavior that directly harmed the children, that’s different. If a parent’s new relationship exposed the kids to danger, instability, or neglect, a judge could factor that in. But the cheating itself? Not a deal-breaker in custody court.
The History of Adultery Laws in Washington
Adultery used to be a crime in Washington. The law was on the books under RCW 9.79.110. But in 1975, the state legislature repealed it. The law officially ended in 1976.
Even before the repeal, prosecutors had basically stopped charging anyone with adultery. The law had become a relic. Washington decided the state had no business policing the private romantic lives of its residents.
Personally, I think this law makes a lot of sense. Criminalizing private relationships between adults is hard to justify. The courts have enough on their plates.
What Still Has Legal Consequences
So nothing happens legally if you cheat? Well, not exactly. Let’s talk about what can still bite you.
If you used marital funds during the affair, expect that to come up in court. Document everything if you are the wronged spouse. Bank statements, receipts, credit card bills. All of it can support a dissipation of assets claim.
If the affair involved a coworker and you are in a professional setting with workplace policies, your employer might take action. That is separate from the law, but the consequences are real. Loss of job, reputation damage, professional discipline.
And honestly, the emotional and social fallout from an affair can be severe. Legal consequences are one thing. Real life consequences are another entirely.
How to Protect Yourself During a Divorce Involving Infidelity
Confused about the difference between what matters legally and what doesn’t? Let me break it down.
First, focus on finances. Gather documentation of any marital money that was spent on the affair. That paper trail is your best legal tool in Washington.
Second, do not waste energy trying to “prove” the affair to influence the divorce judgment. Courts here cannot factor it in the way you might expect. Your attorney’s time is better spent elsewhere.
Third, hire a family law attorney early. Washington divorce law has nuances that are easy to misunderstand. An attorney can tell you exactly what evidence is worth collecting and what is not.
Fourth, if children are involved, focus on showing you are the more stable parent. That matters far more than proving your spouse cheated.
Special Circumstances to Know
Sound complicated? It actually is in a few edge cases. Here are some situations where adultery can play a bigger role.
If the affair involved domestic violence or abuse, courts may consider that when dividing assets. The law does allow for some exceptions when misconduct rises to a level of harm beyond just the affair itself.
If you and your spouse had a prenuptial agreement that included an infidelity clause, that agreement could be enforceable. Some couples build financial penalties for cheating right into their prenup. Washington courts can honor those provisions.
Also, military families should know that federal law still treats adultery differently for active-duty service members. The Uniform Code of Military Justice (UCMJ) includes adultery as a potential offense. That is federal law, not state law, but it applies to Washington residents who serve in the military.
Frequently Asked Questions
Is adultery illegal in Washington State?
No. Washington repealed its criminal adultery law in 1975. You cannot be arrested or charged for having an affair.
Can I use my spouse’s affair as grounds for divorce in Washington?
No. Washington only allows no-fault divorce. You simply state the marriage is irretrievably broken under RCW 26.09.030.
Will my spouse cheating help me get more money in a divorce?
Not directly. But if they spent marital money on the affair, you may be able to claim those funds as dissipated assets.
Does adultery affect child custody in Washington?
Usually not on its own. Courts focus on the child’s best interests. If the affair harmed the children directly, it could become relevant.
Can a prenuptial agreement penalize a cheating spouse in Washington?
Yes. If your prenup includes an infidelity clause, Washington courts can enforce it as a binding contract.
Final Thoughts
Washington keeps things pretty clear when it comes to adultery. It is not a crime. It won’t get you arrested. And it won’t automatically help or hurt your divorce case in most situations.
But that doesn’t mean it has no impact at all. Money spent on an affair can come back around in court. Prenups with infidelity clauses are real. And if children were harmed, the court will hear about it.
Now you know how the law actually works here. Stay informed, ask questions, and if you are going through a divorce, get a family law attorney in your corner. When in doubt, legal advice beats assumptions every time.
