The defense to adultery you’re talking about is called “condonation.” It means the harmed spouse ‘condones’ the act and has agreed to forgive the prior adultery. The answer to your question is “yes,” they can still sue for adultery. Also keep in mind, someone can still file for divorce on those grounds even though the other party tries to deny either the act of adultery, or to claim forgiveness (condonation). If you’re in a position where you may need some low-cost legal help, try here: http://www.sclegal.org/.
 
Because society has a strong interest in preserving marriage, many states (including South Carolina) also have kept some kinds of “fault” in their divorce systems. I’m not sure which “side” of this issue (proving or disproving condonation) you're on. So after taking about condonation, we’ll also look at the way adultery or condonation is or is not proven, and what the result of uncondoned adultery can mean in a divorce. Alimony won’t be awarded to an uncondoned adulterer. http://www.scstatehouse.gov/code/t20c003.php.
 
What Exactly IS Condonation?
 
It’s important not to confuse having “sex” as being exactly the same thing as condonation. Just because two married people consent to have sex does not automatically mean any prior adultery is condoned. Instead, what has to happen is for the couple to resume “normal marital relations.” Having normal relations does not necessarily mean living together, or even resuming sexual relations. Here’s what one court http://scholar. google.com/scholar_case?case=10978907979518422304&q=Nemeth+v.+Nemeth&hl=en&as_sdt=2000000000002&as_vis=1 said about proving condonation:
 
“One of the essential elements of condonation is the forgiving spouse’s knowledge, actual or presumed, of the offense alleged to have been forgiven or condoned. Condonation may be presumed from cohabitation; and lapse of time, or a continuance of marital cohabitation with knowledge of the offense, raises a presumption of condonation.”
 
You can see that cohabitation is one (but not the only one) of the most usual way of proving condonation. Condonation, if proven, removes the act of adultery from the table. But be careful…a spouse may have committed several acts of adultery, and they all must be forgiven. It’s not unusual for a spouse to forgive one act, only to discover more instances of adultery. That’s what happened in another case, and condonation was not proven despite the spouses spending two nights together, apparently without sex, in an attempted reconciliation.
 
Proving Adultery OR Condonation
 
Is it that easy to prove a resumption of marital sex? Not always. For example, some claims of proving adultery, as we’ve talked about above, over-emphasize having intercourse. There are South Carolina cases where one party denied ever having intercourse, based on what seemed to be medical impossibility. As some courts point out, it is not required that parties actually have physical intercourse to commit adultery. There is a case where a woman proved a medical condition that would cause great pain if she had sex. But there was evidence that she had slept in the same bed, without clothes on, after expressing a desire to have a romance with a man. These factors alone, without proof of intercourse, was enough to prove adultery.
 
So keep in mind, this kind of evidence cuts both ways. There can be enough evidence suggesting intimacy (with or without intercourse) to allow a court to decide there has been adultery or a resumption of normal sexual relations in a marriage. Homosexual acts can also be adultery. As another court has said, they will not develop a checklist, to explain every sex act in order to precisely define adultery or condonation.