Polygamy is illegal in the United States because 19th-century federal laws criminalized it, the Supreme Court upheld that criminalization in 1879, and every state has since enacted its own bigamy statute. The ban rests on a settled constitutional principle: religious belief does not exempt anyone from a neutral criminal law. Depending on the state, marrying a second spouse while already married can be anything from a minor infraction to a felony carrying several years in prison, and for non-citizens it carries separate immigration consequences on top.
The 19th-Century Laws That Created the Ban
The federal campaign against polygamy began as a direct response to The Church of Jesus Christ of Latter-day Saints, which practiced plural marriage in the Utah Territory. Congress passed three major statutes to end it.
The Morrill Anti-Bigamy Act of 1862 made bigamy a crime in U.S. territories and restricted the church’s ability to hold property. Enforcement was weak during the Civil War, so Congress returned to the issue with the Edmunds Act of 1882, which reclassified polygamy as a felony and stripped practitioners of the right to vote, serve on juries, or hold public office. The Edmunds-Tucker Act of 1887 went further, disincorporating the church and authorizing the federal government to seize its property. The combined pressure led the church to officially discontinue plural marriage in 1890, clearing the path for Utah’s statehood.
By the time states inherited the question, the federal position had been clear for decades: plural marriage was criminal, and the government would use every tool available to end it.
Reynolds v. United States and the Constitutional Question
The constitutional challenge arrived quickly. George Reynolds, a Latter-day Saint charged under the Morrill Act, argued that plural marriage was a religious duty protected by the First Amendment’s Free Exercise Clause. On January 6, 1879, a unanimous Supreme Court rejected that argument in Reynolds v. United States.1Legal Information Institute. Reynolds v. United States – 98 U.S. 145
The Court drew a line between belief and action. The government cannot tell people what to believe, but it can regulate what they do. Allowing a religious exemption from criminal law would, in the Court’s words, “make the professed doctrines of religious belief superior to the law of the land, and in effect to permit every citizen to become a law unto himself.”1Legal Information Institute. Reynolds v. United States – 98 U.S. 145
Reynolds has never been overturned. It remains the reason a sincere religious belief in plural marriage does not shield anyone from prosecution.
Why States Keep the Ban in Place
The historical reasons explain how the ban started. The reasons it has stayed in place are more practical.
States point first to fraud. Unrecognized spouses create openings for abuse of tax rules, public benefits, and inheritance claims. Social Security survivor benefits, for example, are structured around a single surviving spouse; multiple claimants complicate administration and invite manipulation. States also point to the power imbalances that can develop inside polygamous households, where financial dependence and isolation can leave some spouses with no realistic way to leave.
There is a quieter structural reason too. American family law is built for two people. Divorce, property division, custody, next-of-kin status, and medical decision-making all assume one spouse on the other side. Permitting plural marriage would not just add another chair at the table. It would require rewriting nearly every area of domestic relations law, from how assets divide when one of four spouses leaves to who decides end-of-life care when two spouses disagree.
Criminal Penalties for Bigamy
Every state criminalizes bigamy, but the severity varies widely. Roughly half the states treat it as a felony, with maximum prison sentences reaching five to ten years in states like Georgia and Mississippi. The other half treat it as a misdemeanor, with penalties as mild as 30 days in jail. Fines range from $500 in some states up to $150,000 in Arizona. Most felony states authorize prison terms of one to five years.
Prosecutions are uncommon in practice. The cases that move forward almost always involve an aggravating factor: deceiving a second spouse about marital status, committing immigration fraud through a sham marriage, or collecting extra government benefits through a bigamous arrangement. Prosecutors rarely pursue quiet plural households unless there is abuse, coercion of minors, or financial fraud.
Separately from the criminal penalty, a bigamous marriage is void. It has no legal effect from the moment it occurs. The second spouse acquires no marital property rights, no inheritance rights, and no standing as next of kin. An annulment, if sought, simply confirms what was already true.
Why Obergefell Did Not Change This
After the Supreme Court legalized same-sex marriage nationwide in Obergefell v. Hodges in 2015, many people asked whether the same reasoning would eventually reach polygamy.2Justia U.S. Supreme Court. Obergefell v. Hodges, 576 U.S. 644 (2015) Chief Justice Roberts raised the point in his dissent, arguing that the majority’s logic left no principled basis for excluding plural marriages.
No court has accepted that argument. The distinction courts draw is between expanding access to an existing legal structure and creating an entirely new one. Obergefell extended the two-person framework of marriage to couples who had been excluded from it. Legalizing polygamy would not extend that framework; it would replace it, converting a two-party contract into a multi-party arrangement the law is not built to handle. That difference has been enough to keep polygamy bans in place.
Utah’s 2020 Reform and the Brown Case
Utah, the state most historically tied to polygamy, significantly softened its bigamy penalties in 2020. Basic bigamy was reclassified from a third-degree felony to an infraction, roughly on par with a traffic ticket, carrying a maximum fine of $750 and community service. Felony charges still apply when bigamy involves fraud, coercion, or accompanies serious crimes like domestic abuse, sexual offenses, or child abuse, any of which can elevate the charge to a second-degree felony.3Utah Legislature. SB0102S01 – Bigamy Amendments
Supporters argued that felony penalties drove polygamous families underground, making it harder for vulnerable spouses and children to seek help from law enforcement. Reducing the base penalty was meant to bring these families into contact with social services while preserving serious consequences for coercive and abusive arrangements.
The reform followed years of litigation. The Brown family, stars of the reality show “Sister Wives,” challenged Utah’s statute criminalizing cohabitation with someone other than a legal spouse. A federal district court sided with them in 2013, but the Tenth Circuit reversed in 2016, ruling the case moot because the local prosecutor had adopted a policy of declining to pursue bigamy absent fraud, coercion, or other criminal conduct.4Justia Law. Brown v. Buhman, No. 14-4117 (10th Cir. 2016) The court never ruled on whether the ban itself was constitutional. The outcome captured the broader pattern: states leave consenting-adult polygamy largely alone in practice while keeping the law available for cases involving exploitation.
Immigration Consequences for Non-Citizens
Federal immigration law treats polygamy as a separate problem from state criminal law. Under 8 U.S.C. ยง 1182(a)(10)(A), any immigrant coming to the United States to practice polygamy is inadmissible. The bar applies across all immigrant visa categories, not just spousal petitions, and no waiver is available.5Office of the Law Revision Counsel. 8 USC 1182 – Inadmissible Aliens Mere belief in polygamy, or past practice abroad, is not enough on its own; an officer must find the applicant actually intends to practice polygamy after arrival. The provision does not reach nonimmigrant visa holders such as tourists or temporary workers.6U.S. Department of State. Ineligibility Based on Other Activities – INA 212(a)(10)
For green card holders, practicing polygamy after obtaining permanent resident status can trigger deportation and will almost certainly block naturalization. Citizenship applicants must show good moral character, and practicing polygamy is a specific bar. Immigration authorities read the practice broadly: if a spouse maintains a polygamous relationship, even one conducted entirely in another country, U.S. Citizenship and Immigration Services may treat the applicant as practicing polygamy as well.
If You Married Someone Already Married Without Knowing
Not everyone in a bigamous marriage entered it knowingly. The person who marries someone without realizing that person is already married faces a hard legal reality: the second marriage is void, which means it never existed in the eyes of the law. Someone who lived as a married spouse for years can be left with no claim to marital property, no spousal support, and no inheritance rights.
A number of states soften this through the putative spouse doctrine. Under that rule, a person who entered the marriage in genuine good faith, honestly unaware of the existing marriage, can be awarded some or all of the property and support rights they would have had as a legal spouse. The requirement is good faith: the person must not have known or had reason to know about the prior marriage. In states that recognize the doctrine, the legal spouse and the putative spouse share marital property rights, which can produce complicated division proceedings but prevents the unknowing spouse from walking away with nothing.