Informational image summarizing early Mormon polygamy practices and U.S. federal anti-polygamy legislation. — “Key legal events that defined the U.S. stance on polygamy, including LDS Church history and major federal acts.”

Polygamy in US Law: Legality, History, and Constitutional Challenges

Author Name: Nahyan | uslawguide

Last Updated: June 29, 2025

The concept of polygamy, the practice of having more than one spouse simultaneously, stands in stark contrast to the firmly established legal framework of monogamous marriage in the United States. While polygamy holds deep religious and cultural significance for some communities, US law unequivocally prohibits it, classifying it as a criminal offense in every state. This firm stance is rooted in a complex history involving 19th-century religious movements, landmark Supreme Court decisions, and ongoing debates about the limits of religious freedom. Understanding the legal status of polygamy requires delving into the historical struggles that defined its illegality, the constitutional arguments that have both challenged and upheld its prohibition, and its unique place within the broader spectrum of laws protecting US Amendments Bill of Rights. For legal precedent, the Supreme Court’s ruling in Reynolds v. United States (1879) remains foundational.

Historical Context: Mormonism and the Genesis of Anti-Polygamy Laws

The legal prohibition of polygamy in the United States is largely shaped by the historical conflict between the federal government and the Church of Jesus Christ of Latter-day Saints (LDS Church), commonly known as Mormons, in the 19th century.

Early Mormon Practice: Beginning in the 1840s, the LDS Church openly practiced “plural marriage” (polygamy) as a religious doctrine, believing it was commanded by God. As the Mormon community settled in Utah Territory, this practice brought them into direct conflict with the monogamous norms and emerging anti-polygamy sentiment of the broader American society.

Federal Anti-Polygamy Legislation: The federal government viewed polygamy as a moral offense, a threat to the traditional family structure, and an impediment to Utah’s statehood.

Morrill Anti-Bigamy Act of 1862: This was the first federal law specifically targeting polygamy, making bigamy a crime and disincorporating the LDS Church.

Edmunds Act of 1882: This law criminalized polygamous cohabitation, disenfranchised polygamists, and made them ineligible for public office or jury service.

Edmunds-Tucker Act of 1887: This further intensified federal efforts, dissolving the LDS Church as a legal entity, confiscating its property, and requiring a test oath disavowing polygamy for voters and officeholders. These legislative moves paralleled broader federal efforts to define moral standards through law, echoing the spirit of reforms underlying the Constitutional Amendment Louisiana.

The LDS Church’s Stance: Facing immense legal pressure, including the imprisonment of many leaders and the threat to the church’s existence, the LDS Church officially renounced the practice of plural marriage in 1890 (the “Manifesto”). This pivotal moment paved the way for Utah’s statehood in 1896 and cemented polygamy’s illegal status in federal and, subsequently, state laws. For background on the Morrill Act’s impact, see.

The Legal Status of Polygamy in US Law

Today, polygamy is illegal in every state in the United States. While individual state laws may vary slightly in their precise definitions and penalties, the overarching legal principle is consistent: marriage must be between two individuals, and simultaneously being married to more than one person is a criminal offense, typically classified as bigamy or polygamy.

Criminal Offenses: Most states have laws against:
- Bigamy: The act of entering into a marriage with one person while still legally married to another. This usually applies even if the subsequent marriage is not considered legally valid.
- Polygamy/Polygamous Cohabitation: Some states have broader laws that criminalize cohabitation with multiple “spouses” even if only one marriage is legally recognized.
Consequences: Beyond criminal penalties (which can range from misdemeanors to felonies depending on the state and circumstances), involvement in polygamous relationships can lead to:
- Invalidation of Marriages: Only the first marriage is recognized as legal. Subsequent “marriages” are void.
- Loss of Benefits: Individuals in polygamous unions cannot claim spousal benefits (e.g., social security, inheritance) from multiple partners.
- Custody Issues: Courts typically prioritize the welfare of children and may view polygamous living arrangements negatively in child custody disputes, potentially impacting parental rights.
- Social Services: Polygamous families may face scrutiny from child protective services, especially in cases where child marriage or abuse is suspected.

Constitutional Challenges: Religious Freedom vs. Public Policy

The legal prohibition of polygamy has frequently been challenged on constitutional grounds, primarily invoking the First Amendment’s protection of religious freedom. However, the Supreme Court has consistently upheld the government’s right to criminalize polygamy.

Reynolds v. United States (1879): This is the landmark Supreme Court case on polygamy. George Reynolds, a Mormon, argued that the Morrill Anti-Bigamy Act violated his First Amendment right to religious freedom. The Court, in a unanimous decision, upheld the law, establishing a crucial distinction:
- Belief vs. Practice: The Court ruled that while the First Amendment protects the freedom to believe in any religious doctrine, it does not protect the freedom to act on those beliefs if those actions violate valid criminal laws of society.
- Societal Interest: Chief Justice Morrison Waite stated that “marriage, while from its very nature a sacred obligation, is nevertheless, in most civilized nations, a civil contract, and usually regulated by law.” He argued that allowing polygamy would subvert the monogamous foundation of society.
Subsequent Affirmations: Reynolds has been consistently affirmed by the Supreme Court. Later cases, though not directly on polygamy, have reinforced the principle that religious freedom does not provide an absolute exemption from generally applicable laws.

Modern Debates and the Future of Polygamy in US Law

While the LDS Church officially abandoned plural marriage in the late 19th century, certain fundamentalist Mormon groups and other religious or secular communities continue to practice polygamy in various forms, often in isolated areas. This has led to ongoing legal and social challenges:

The Lawrence v. Texas (2003) & Obergefell v. Hodges (2015) Effect: These landmark Supreme Court decisions, which decriminalized consensual same-sex sexual activity and established a constitutional right to same-sex marriage, respectively, sparked speculation about whether the legal arguments for privacy and marriage equality could extend to polygamy.
- Distinction: Legal scholars and courts have largely distinguished these cases from polygamy. Lawrence focused on individual sexual autonomy within private conduct, not on the legal recognition of marriage. Obergefell expanded the right to marriage to same-sex couples, but it reaffirmed the definition of marriage as between two individuals, implicitly upholding the monogamous standard.
- Lack of Precedent: No Supreme Court ruling since Reynolds has created any opening for the legalization of polygamy. Courts typically point to the state’s legitimate interests in protecting women and children, preventing exploitation, and maintaining the traditional definition of marriage.
Focus on Abuse and Coercion: Modern legal enforcement against polygamy often focuses less on consensual adult relationships (unless they involve clear bigamy) and more on prosecuting cases involving child marriage, sexual abuse, welfare fraud, and other crimes that can be associated with some polygamous communities, particularly those with hierarchical, isolated structures.
Decriminalization Debates (Not Legalization): While full legalization remains highly improbable, some academics and advocates have discussed the decriminalization of polygamous cohabitation among consenting adults, arguing that criminalizing such relationships does more harm than good by driving them underground. However, this differs significantly from legal recognition of multiple marriages.

Conclusion

Polygamy remains firmly illegal under US law, a stance solidified by over a century of legislative action and unwavering Supreme Court precedent. The landmark Reynolds v. United States decision established the enduring principle that while religious beliefs are protected, religiously motivated practices that violate generally applicable criminal laws are not immune from prosecution. Despite evolving interpretations of marriage and individual liberty, the legal definition of marriage in the United States continues to be exclusively monogamous. This firm prohibition reflects a deeply ingrained societal consensus and the state’s recognized interest in regulating family structures and protecting vulnerable individuals, continuing to shape a unique aspect of American laws.

Frequently Asked Questions About Polygamy in US Law

Q: Is polygamy legal in any state in the U.S.? A: No, polygamy is illegal in every state in the United States. US law defines marriage as a union between two individuals, and entering into or maintaining multiple simultaneous marriages is a criminal offense, typically bigamy.

Q: Why is polygamy illegal in the U.S.? A: Polygamy is illegal primarily due to historical precedent stemming from conflicts with 19th-century Mormon polygamy, which the federal government viewed as a threat to societal norms and public order. The Supreme Court upheld this stance, ruling that while religious belief is protected, religiously motivated actions that violate valid laws are not.

Q: What was the significance of Reynolds v. United States (1879) regarding polygamy and US law? A: Reynolds v. United States was the landmark Supreme Court case that upheld the federal anti-bigamy law, ruling that the First Amendment’s freedom of religion clause protects religious belief but not religious practices that violate criminal laws deemed essential to public order, such as monogamous marriage.

Q: Does the legalization of same-sex marriage affect the legality of polygamy in the U.S.? A: No, the legalization of same-sex marriage by Obergefell v. Hodges (2015) did not affect the legality of polygamy. Obergefell affirmed the right to marry for same-sex couples but reaffirmed the definition of marriage as a union between two individuals, thereby implicitly upholding the monogamous standard under US law.

Q: Are there any exceptions to the laws against polygamy for religious reasons? A: No, there are no exceptions for religious reasons. The Supreme Court has consistently held since Reynolds v. United States that religious freedom does not exempt individuals from generally applicable criminal laws prohibiting polygamy.

Responsible Disclaimer: This article provides general information about the legal status of polygamy in the U.S. and its historical and constitutional context. It is not intended as legal advice. For specific interpretations of family laws, criminal laws, or constitutional rights, readers should consult a qualified attorney provider.