.The FLDS has practiced polygamy for over a hundred years, and still do so openly without prosecution. The authorities can’t interfere with a religious marriage, due to freedom of religion, even if plural. They purposefully do not obtain multiple civil marriages.
Well, now you’re getting into technicalities, because the state doesn’t consider it a marriage unless there is a civil marriage. A religious marriage, according to the state, is no marriage (although it may become one after a while in states that recognize common-law marriage). Shacking up with a girlfriend (even if you call her another wife), even if you’re already married, is not a crime. If they would obtain a second marriage license, then they very well might be charged with bigamy.
But states sometimes do prosecute bigamy cases when a second (or later) civil marriage is enacted. In fact, is has happened at least twice in the past month (see links below). I don’t know if the motivation in either case was religious, but even if it is, it is still not a defense.
http://www.fox59.com/news/wxin-indiana-soldier-bigamy-120810,0,6798571.story
http://www.wqow.com/Global/story.asp?S=13648350
In the end, it doesn’t even matter, as I’ve already shown above that freedom of religion does not mean an absolute freedom to practice said religion.
The Wolf