Bigamy is the act of a married person getting married to another person, while knowingly already being married. In order to enter into a marriage, both parties have to be legally able to wed. If either party is already married, they would not be allowed to legally marry a second time without first effecting a dissolution of the first marriage.
It is a crime in most countries to commit bigamy, but the sentencing can greatly differ—from being a misdemeanor to being considered more severely as a felony.
The only way a person can be charged with bigamy is if the court can prove that the person had no reason to believe that they were not still married in the first instance, such as when a person believes that they filed all the necessary divorce papers but did not know that their previous partner (spouse) had not signed the papers, thus making the divorce incomplete.
Although illegal, the act of bigamy does not usually carry a severe penalty. The law dictates that both a monetary fine and jail time can be included in a verdict; contemporary cases would have allowed the bigamist to walk free with a suspended sentence or very small fine.
The first law against bigamy in the United States was in 1862, called the Morrill Anti-Bigamy Act. The purpose of the act was to break up the land monopoly in Utah, which was held by The Church of Jesus Christ of Latter-day Saints, who endorsed (and still endorse) polygamy. The addition of this law led to the Latter-day Saints officially outlawing polygamy in 1890, although in modern times, there have been instances of polygamy still seen in Utah within this group.
In 2013, a U.S. District Court judge in Utah struck down part of the bigamy laws as unconstitutional. Although bigamy was illegal in all 50 states, it was further defined in Utah to include living with a person in a manner that is like a marriage if a marriage certificate was issued to that person and someone else. The judge determined that this was a step too far and since 2013, the Utah law is in line with all other states.
Internationally in Christian-based countries, the act of bigamy is illegal, but in Islamic-based countries it is considered legal. Regardless of the religious background of the American citizen, when in the USA, no one is expected or allowed to have more than one spouse. If a person who is not a U.S. citizen intends to gain a visa to live and work in the USA, and they lie about being a bigamist or being in a polygamist relationship, the visa will not be given.
Other than the Latter-day Saints, there have been reports of bigamy within the Muslim community as well, although these are not as noticeable as the Mormon bigamists, as their marriages took place in a foreign country and they are not noted within their visa and citizenship applications due to the chance of being excluded due to that.