Is it illegal?

Is it illegal to cheat on you husband/wife? Just wondering... :)
Some places hold a law against it, but it's rarely enforced. Kind of like sodomy law. In some states.
There are a few US States that still have adultery laws on paperwork but, following "Lawrence v Texas", I believe they would not withstand a constitutional appeal.

In the military, though, the situation is different. Adultery is a crime under the UCMJ, and IS prosecuted.

Richard
It's not illegal, as in you won't run to jail or have a criminal record for adultery. It is probably still on some books somewhere, surrounded by some state, but like many other stupid "crimes" is not enforced. However, while it isn't illegal, it is grounds for divorce and surrounded by community property states it can result in an unequal division of property.
it is if your contained by the military. and if you get caught, you could have your bargaining chip taken away if going through a divorce andyour hte FALSE one. its not illegal you won't be arrested by the police but it sure can effect your marriage and your family
In some jurisdictions.
Hard to believe but it is. Almost all look the other approach and don't enforce it, which is silly, they should revoke the law. With the exception of fundamentalist religious countries. Yes, adultery is still considered a crime in some states and is still grounds for a hostile divorce in plentifully of others. It may not get you in jail but it'll hurt your wallet! :)