We've all heard reports of celebrity couples who are rumored to have an infidelity clause in their prenuptial or postnuptial agreement. If one spouse is unfaithful, he or she has to pay a significant amount of money to the other one or forfeit money in a divorce.

If they divorce, the cuckolded spouse may get a significantly greater share of the assets. Meanwhile, if the person who cheated is the one with less money, he or she may to take a reduction in spousal support from what is laid out in the agreement.

An Increasingly Common Clause

This particular type of lifestyle clause has become more common over the years among the general public as fewer states have fault divorces. Even if adultery is listed as the reason for the divorce, the cheating spouse is less likely to be ordered to pay more as a result than in years past.

So, do infidelity clauses work? Some attorneys say they do, because they can give spouses a strong financial incentive not to stray. (However, it could just cause them to be more careful not to get caught.) Further, when a couple discusses their feelings about infidelity as they draft their prenup, they may be less likely to give into temptation.

How Is Infidelity Proven?

We've all seen TV shows and movies where private investigators are stalking a spouse believed to be cheating to a "no-tell motel" or a darkened restaurant to catch him or her canoodling with someone else.

It's important to define in the prenup or postnup what activities constitute infidelity and what evidence needs to be presented. Sometimes spouses will simply admit infidelity rather than have their sexual activities presented in court.

Court decisions have varied in cases where spouses have attempted to invoke their infidelity clause. When you want to include such as clause in a prenup or postnup, it's essential to find out from your family law attorney whether such a clause is valid in your state. Then, it's important to determine how you wish to define infidelity, what proof you need to provide if you invoke the clause, and what the repercussions will be for a spouse who violates the clause.