Polygamy was outlawed in federal territories by the Edmunds Act, and there are laws against the practice in all 50 states, as well as the District of Columbia, Guam, and Puerto Rico. Because state laws exist, polygamy is not actively prosecuted at the federal level.
Many US courts (e.g. Turner v. S., 212 Miss. 590, 55 So.2d 228) treat bigamy as a strict liability crime: in some jurisdictions, a person can be convicted of a felony even if he reasonably believed he had only one legal spouse. For example, if a person has the mistaken belief that their previous spouse is dead or that their divorce is final, they can still be convicted of bigamy if they marry a new person.
Federal law
According to the Edmunds Act, bigamy is punishable by "a fine of not more than five hundred dollars and by imprisonment for a term of not more than five years". However, because state laws exist, polygamy is not actively prosecuted at the federal level, but the practice is considered "against public policy".
Legislation
Anti-polygamy bill of 1854
The first legislative attempt to discourage polygamy in Utah was presented in the 33rd Congress and was debated in May 1854. The bill included the provision that any man who had more than one wife would not be able to own land in the Utah Territory. This bill was defeated in the House of Representatives after multiple representatives argued that the federal government did not have the authority to legislate morals in the states.
1862 Morrill Anti-Bigamy Act
In 1862, the Morrill Anti-Bigamy Act became law. The Act criminalized the practice of polygamy, unincorporated the Church of Jesus Christ of Latter-day Saints (LDS Church), and limited the church's real estate holdings. According to an article in the Virginia Law Review, legislators did not actually believe that the bill would end polygamy. Speeches given during the debate did not include an explanation of how the bill would eliminate or decrease polygamy in Utah. Despite many members of Congress knowing that the bill would be ineffective, Morrill (the sponsor of the bill) encouraged his fellow legislators to pass the bill in its current state.
Legislators did not explain why they felt the bill would be ineffective. One of the weaknesses listed in theVirginia Law Review is that the law required prosecutors to present an "insurmountable burden of proof." Legislators were also concerned that jury nullification would prevent polygamists from being convicted. The Act was largely understood to be unconstitutional and was only enforced in rare cases. While, the Act outlawed bigamy in the US territories, it was seen to be largely weak and infective at preventing people from practicing polygamy. However, due to the continuous threat of legislation targeting polygamy and the church, Brigham Young pretended to comply.
On January 6, 1879, the Supreme Court upheld the Morrill Anti-Bigamy Act in Reynolds v. United States.
Wade, Cragin, and Cullom Bills
The Wade, Cragin, and Cullom Bills were anti-bigamy legislation that failed to pass in the US Congress. The bills were all intended to enforce the Morrill Act's prohibition on polygamy with more punitive measures. The Wade Bill of 1866 had the power to dismantle local government in Utah. Three years after the Wade Bill failed, the Cragin Bill, which would have eliminated the right to a jury for bigamy trials, also did not passed. Following the failures of the Wade and Cragin Bills, the Cullom Bill was introduced.
The Cullom Bill would have prevented those practicing polygamy from voting, serving on a jury, holding public office, becoming a citizen of the United States, and receiving the benefits of the homestead laws.
The leadership of the LDS Church publicly opposed the Cullom Bill. Op-eds in church-owned newspapers described the bill as unjust and dangerous to Mormons. The introduction of the Cullom Bill led to protests by Mormons, particularly women. Mormon women organized indignation meetings to voice their disapproval of the bill. The strong reaction of women surprised many onlookers and politicians. Outside of the church, Mormon women were seen as weak and oppressed by their husbands and the men of the church. The political activism in support of polygamy of Mormon women was unexpected as they had been portrayed as powerless.
Despite a Republican-dominated Congress, the Cullom Bill failed in the Senate in 1870.