Polygamy is not legal anywhere in the United States. Every state makes it a crime to marry someone while you are still legally married to another person, a second marriage entered that way is void from the start, and federal immigration, tax, and benefits law all recognize only one spouse at a time. The constitutional challenge to this rule failed at the Supreme Court in 1879 and has not succeeded since.
State Bigamy Laws Do the Work
Marriage is regulated by the states, so the criminal prohibition on polygamy lives in state bigamy statutes rather than a single federal law. Every state has one. Most classify bigamy as a felony; a few treat it as a misdemeanor. Maximum prison terms range from 30 days to 10 years, and fines run from a few hundred dollars into the tens of thousands.
The core rule is the same everywhere. You cannot enter a legal marriage while a prior marriage remains undissolved. It does not matter whether the first marriage happened in another state or another country, whether you and your first spouse live apart, or whether your first spouse consents. Until that first marriage ends by divorce, annulment, or death, a second marriage is void and attempting it is a crime.
Utah Is the Outlier
In 2020, Utah reclassified bigamy among consenting adults from a third-degree felony carrying up to five years in prison to an infraction punishable by fines and community service. The change did not legalize polygamy. Entering multiple marriages is still prohibited, and bigamy committed through fraud, coercion, or in connection with domestic abuse remains a felony. The reclassification was aimed at a practical problem: prosecutors rarely charged plural families living peacefully, and the felony label discouraged members of those families from reporting actual abuse.
The Common Law Marriage Trap
About ten states and the District of Columbia still recognize common law marriage, where a couple becomes legally married without a license or ceremony if they meet the state’s requirements, typically living together, presenting themselves publicly as married, and intending to be married. A common law marriage is just as binding as a ceremonial one. If you entered a common law marriage in a state that recognizes them and never formally dissolved it, marrying someone else carries the same legal exposure as if a certificate were on file.
Defenses That Rarely Work
Courts have consistently rejected the arguments people reach for first. A pending divorce is not a defense; until the decree is final, the first marriage is still valid. Marrying in a different state or country does not help, because the prohibition follows the person. Never having consummated the first marriage is irrelevant, since consummation is not an element of a valid marriage.
One defense does carry weight in most states: a good-faith belief that the prior marriage was legally dissolved. If you received a divorce decree and reasonably relied on it, only to learn later that the decree was defective for procedural reasons, most courts recognize that honest mistake. Some states also provide a defense when a spouse has been absent and presumed dead for a specified number of years, often five or seven.
Religious Belief Is Not a Defense
The leading case is Reynolds v. United States, decided by the U.S. Supreme Court in 1879. George Reynolds, a member of the Church of Jesus Christ of Latter-day Saints, argued that his religious duty to practice plural marriage shielded him from prosecution under the federal anti-bigamy statute. The Court rejected the argument entirely, holding that religious belief cannot justify an act the criminal law forbids.1Justia Law. Reynolds v. United States, 98 U.S. 145 (1878)
The Court drew a line between belief and conduct. You may believe polygamy is morally right or religiously required, and the government cannot punish the belief. The moment you act on it by entering a second legal marriage, the law treats you no differently than anyone else who commits bigamy. The Court added that the statute “inexorably implies the criminal intent” even when the defendant genuinely believed the marriage was permissible.2Library of Congress. U.S. Reports: Reynolds v. United States, 98 U.S. 145 (1879) More than 140 years later, Reynolds has never been overturned.
What a Void Marriage Means in Practice
A bigamous marriage is void from the start. It never had legal force, which creates practical problems even after any criminal matter is resolved.
- Property: The second spouse has no automatic claim to marital property under family law. In some states, the “putative spouse” doctrine offers limited protection to a spouse who entered the marriage in good faith, genuinely not knowing about the first marriage. A putative spouse may receive a share of property acquired during the relationship, though this varies significantly by jurisdiction.
- Inheritance: Without a valid marriage, the second spouse has no spousal inheritance rights under intestacy laws. A will can still name anyone as a beneficiary, but the automatic protections that come with legal marriage do not apply.
- Children: Children born during a void marriage are not penalized for their parents’ legal situation. They retain the same rights to child support and inheritance from both parents as children born into a valid marriage.
Immigration and Citizenship
Federal immigration law treats polygamy as a reason to keep people out of the country. Under 8 U.S.C. ยง 1182, any immigrant coming to the United States to practice polygamy is inadmissible, meaning they cannot receive a visa or enter.3Office of the Law Revision Counsel. 8 U.S.C. 1182 – Inadmissible Aliens
For people already in the United States seeking citizenship, polygamy creates a separate barrier. Naturalization requires demonstrating good moral character during a statutory period. U.S. Citizenship and Immigration Services treats anyone who has practiced polygamy during that period as failing the good moral character requirement, which blocks the application. USCIS officers review marriage and divorce certificates, birth certificates of children, and prior visa petitions to detect potential polygamous relationships, and a separate bigamy finding can also trigger denial under the agency’s “unlawful acts” provision.4USCIS. Chapter 5 – Conditional Bars for Acts in Statutory Period
Taxes and Social Security
The federal tax system recognizes only one legal spouse. You cannot file a joint return with more than one person, and you cannot claim married filing jointly or married filing separately status with someone you are not legally married to. If a second marriage is void due to bigamy, the IRS treats that second spouse as unmarried regardless of how the household actually functions.
A partner in an unrecognized union might qualify as a dependent under the “qualifying relative” rules, but the requirements are strict. The person must live with you for the entire year, earn less than $5,200 in gross income based on the most recently published threshold, and you must provide more than half of their total support. The IRS also disqualifies anyone whose relationship with you violates local law, so if your living arrangement constitutes bigamy or unlawful cohabitation in your state, you cannot claim that person as a dependent at all.5Internal Revenue Service. Publication 501 (2025), Dependents, Standard Deduction, and Filing Information
Social Security spousal and survivor benefits require a valid legal marriage. The Social Security Administration determines marriage validity under the law of the state where the worker was domiciled. A second spouse in a bigamous marriage has no claim to spousal benefits, survivor benefits, or the lump-sum death payment. One narrow exception exists: under the “deemed spouse” provision, a person who married in good faith without knowing about the prior marriage and was living with the worker at the time of death may qualify for survivor benefits despite the marriage being technically void.6Social Security Administration. PR 05105.010 District of Columbia
What the Law Does Not Prohibit
The law prohibits multiple legal marriages, not multiple relationships. Polyamory, where a person maintains romantic relationships with more than one partner with everyone’s knowledge and consent, is not a crime. Neither is living with multiple partners. What triggers criminal liability is obtaining a marriage license while a prior marriage exists.
Three or more adults can share a home, raise children together, own property jointly, and hold themselves out as a family unit without violating bigamy laws, so long as they do not attempt to formalize more than one marriage at a time. Domestic partnership registries, where they exist, are generally limited to two people under state law. In 2020, the city of Somerville, Massachusetts approved an ordinance allowing domestic partnerships with more than two partners; the local registration does not confer the state or federal benefits of marriage, but it was the first formal government recognition of multi-partner households in the United States.
Multi-partner households that want legal protections for shared property and finances can use private contracts. Many states enforce written cohabitation agreements between unmarried partners, treating them similarly to prenuptial agreements. These contracts can address how property is divided if the relationship ends, who owns what, and how shared expenses are handled. The one firm limit is that the agreement cannot be structured as payment for a sexual relationship; courts will not enforce a contract that looks like it exchanges property rights for sex. Grounded in shared financial commitments, a cohabitation agreement holds up much like any other private contract, and it is far more reliable than hoping a court will sort things out after the relationship ends.