In the context of divorce law, you can "plead no contest" by abstaining from defending yourself against the allegations contained in your spouse’s complaint or petition for divorce. You might do this at trial or in depositions by invoking your Fifth Amendment right against incriminating yourself, depending on your state’s laws. Generally, adultery would have to be a criminal offense in your jurisdiction for your Fifth Amendment right to apply. Alternatively, you might simply decide not to deny your spouse’s adultery grounds when you file an answer to her complaint. In either case, your decision not to challenge her grounds can have a negative effect on your divorce.
Marital misconduct typically plays no role in property division in community property states, but this isn't always true when the marital misconduct is adultery. Normally, community property law dictates an even division of marital property between spouses. However, if you spent marital funds -- including your own income -- on your paramour, a judge may order you to return at least half that money to your spouse by awarding her additional property. If you live in an equitable distribution state, judges have a great deal of discretion when dividing marital property. The result is not always a 50/50 split to begin with. In these jurisdictions, committing adultery can influence a judge to order a 60/40 or even a 70/30 division in favor of your spouse, if you don’t successfully deny her charges.
In states such as Virginia and Georgia, statutes bar an adulterous spouse from receiving alimony or spousal support. In states whose legislative codes contain no such provisions, the ultimate decision regarding an award of alimony comes down to the opinion of a judge. Judges are human. Although they may have heard thousands of cases of straying spouses over the years, this doesn’t mean they will approve of your behavior, especially if you don't try to defend yourself against the charges. As a result, you may end up paying alimony due to your adulterous behavior -- it wouldn’t be fair for your spouse to lose the marital standard of living she had become accustomed to because your infidelity ended your union.
Technically, adultery should have no effect on your post-divorce relationship with your child. In reality, all states base custody decisions on a doctrine known as the “best interests of the child.” Your affair won’t affect your child’s best interests by itself, but judges will consider it if you caused your child distress by exposing her to your adulterous behavior, clearly an action not in her best interests. In states that weigh the morality of parents when making custody decisions, your adulterous behavior could have an effect on a judge’s decision as well.
Rather than “pleading no contest,” you might want to consult with an attorney to explore the benefits of denying your spouse’s allegations. By doing so, you force her to prove that you strayed, which is not always easy to do. Some states require proof of your infidelity even if you admit to being unfaithful. If she fails to provide the court with proof, a judge can’t award her a divorce on adultery grounds. Therefore, your behavior cannot factor into the judge's decisions regarding support and property, though it might still influence custody. You can also challenge your spouse's grounds by presenting the court with something called an “affirmative defense.” This means you’re not necessarily denying you committed adultery, but you’re giving the court a legally viable reason not to hold it against you. For example, perhaps your spouse knew what you were doing, but condoned the behavior as evidenced by her willingness to maintain the marriage for a while after she learned of your infidelity.