A polygamist, under U.S. law, is a person who has more than one spouse at the same time, whether through a second marriage ceremony or by holding themselves out as having multiple spouses simultaneously. The act of marrying while already married is called bigamy, and it is a crime in all 50 states, carrying penalties that range from a small fine to ten years in prison depending on the jurisdiction.1Cornell Law Institute. Legal Information Institute – Polygamy The second marriage is also void from the moment it happens, which means the additional spouse walks away with none of the inheritance, tax, or benefit rights that normally come with being married.
What the Law Actually Looks At
The legal test is narrow. If a person already has a living spouse and no court has finalized a divorce or declared that spouse legally dead, any new marriage triggers the label. The Supreme Court set out the definition in Murphy v. Ramsey (1885): a polygamist is anyone who marries another person while knowing they already have a living husband or wife.1Cornell Law Institute. Legal Information Institute – Polygamy
What matters is the legal act, not the household arrangement. Obtaining a marriage license, going through a ceremony, or taking any step that would ordinarily create a valid marriage is enough. The relationship doesn’t need to involve cohabitation, and the motivation doesn’t need to be religious. Because marriage is a contract between two people, someone already party to one marriage lacks the legal capacity to enter another.
Federal law also draws a distinction between two overlapping terms. Bigamy is the act of marrying a second spouse while already married. Polygamy is the broader practice of maintaining multiple spouses at once, which can include informal or culturally recognized unions without any marriage license. A person can be a polygamist in the eyes of federal immigration authorities even if they never filed a second marriage certificate.
Criminal Penalties Across the States
Every state criminalizes bigamy, but the severity varies widely. Most states classify it as a felony; roughly 15 treat it as a misdemeanor. Sentences run from as little as 30 days at the low end to ten years at the high end, with fines from $500 to $150,000. A typical felony conviction brings one to five years in prison.
Some states separate the simple act of marrying twice from the broader practice of plural marriage, imposing harsher penalties on the latter. Utah, long the state most associated with these prosecutions, moved in the opposite direction in 2020, reclassifying basic bigamy from a felony to an infraction. The revised Utah law still escalates to a third-degree felony when fraud or coercion is involved, and to a second-degree felony when the bigamous relationship involves child abuse, domestic violence, human trafficking, or similar serious crimes.2Utah Legislature. Utah Code 76-7-101 – Bigamy
Defenses That Work, and One That Doesn’t
Not every person who remarries while still legally married intended to break the law. Several affirmative defenses have made their way into state statutes:
- Belief that the prior spouse was dead, usually requiring the defendant to show they made reasonable efforts to confirm the death rather than simply assumed it.
- Extended absence of the prior spouse without contact, often five or seven years, with no reason to believe they were still alive.
- Reliance on a court divorce decree or annulment that later turned out to be invalid, when the defendant didn’t know about the defect.
- A reasonable belief, based on objective facts, of eligibility to remarry.
One defense routinely fails: believing that a separation agreement, a private contract between spouses, or an informal understanding ended the first marriage. Only a court-issued divorce decree or annulment dissolves a marriage. A person who remarries based on a handshake deal with an ex is still committing bigamy, even if both former spouses agreed the marriage was over.
Why the Second Marriage Is Void
A bigamous marriage isn’t just a crime for the person who entered it. It also creates a civil disaster for the additional spouse. Under common law adopted in virtually every state, a marriage entered while a prior one still exists is void from its inception. Unlike a voidable marriage, which stays valid until a court cancels it, a void marriage is treated as if it never happened. No court order is needed to end it because, legally, there was nothing to end.
The practical fallout is severe:
- Property acquired during the relationship isn’t automatically shared. Community property rules and equitable distribution statutes apply only to valid marriages.
- If the bigamist dies without a will, the additional spouse typically cannot claim a share under intestacy laws. A will naming the additional spouse may still be honored, but the spousal share guaranteed by law to a surviving husband or wife does not apply.
- Family courts in most states lack authority to order alimony or spousal support when there was no valid marriage to begin with.
Federal benefits follow the same logic. The IRS determines marital status based on whether a marriage is recognized under state law, and a void bigamous marriage fails that test.3Internal Revenue Service. Publication 501 (2025), Dependents, Standard Deduction, and Filing Information The additional spouse cannot file a joint return or claim the marital deduction. Social Security spousal and survivor benefits require a valid marriage lasting at least one year (or nine months for survivor benefits), neither of which an additional spouse in a void marriage can satisfy.4Social Security Administration. What Are the Marriage Requirements to Receive Social Security Benefits
Protection for an Innocent Spouse: The Putative Spouse Doctrine
The harshness of the void-marriage rule has pushed roughly a dozen states to carve out an exception. Under the putative spouse doctrine, a person who entered a bigamous marriage with a genuine, good-faith belief that it was valid can claim some or all of the rights normally reserved for legal spouses. The doctrine comes from the Uniform Marriage and Divorce Act, though adopting states vary in how generous the protection is.
To qualify, the additional spouse must show they honestly did not know about the prior marriage. The test in most adopting states is subjective: what did this person actually believe? If there were warning signs and the spouse ignored them, the doctrine won’t help.
Where it applies, a putative spouse can typically seek a share of property accumulated during the relationship, treated as if it were marital property. Some states also allow spousal support. A few extend the protection to wrongful death claims and inheritance rights. The doctrine doesn’t make the void marriage valid. It prevents one person’s fraud from stripping the innocent party of everything.
States that don’t recognize the doctrine leave the innocent party with limited options, usually fraud claims or unjust enrichment theories that are harder to prove and less generous in what they recover.
Immigration Consequences
Polygamy creates serious problems under federal immigration law, separate from any state criminal exposure. Under 8 U.S.C. ยง 1182(a)(10)(A), any immigrant coming to the United States to practice polygamy is inadmissible, meaning they can be denied a visa or turned away at the border.5Office of the Law Revision Counsel. 8 USC 1182 – Inadmissible Aliens
For noncitizens already in the country, practicing polygamy is a conditional bar to establishing the “good moral character” required for naturalization. USCIS defines polygamy broadly as “the custom of having more than one spouse at the same time,” a definition that covers informal arrangements and culturally recognized unions, not just legally documented marriages.6U.S. Citizenship and Immigration Services. Chapter 5 – Conditional Bars for Acts in Statutory Period The bar applies during the statutory period leading up to the naturalization application and through the oath of allegiance.
Because the bar is conditional rather than permanent, an applicant who stops the practice may eventually qualify for naturalization after demonstrating good moral character for the required period. A separate concern is a bigamy conviction itself, which could trigger removal proceedings as a crime involving moral turpitude depending on the state classification and sentence. Anyone facing both a criminal case and an immigration case at the same time risks a resolution in one that worsens the other.
Where Children Stand
Children born into a bigamous marriage face a legal status question that most states have resolved in their favor. Historically, children of void marriages were considered illegitimate and denied inheritance rights. Modern statutes in the vast majority of states now treat them as legitimate, at least when one parent believed the marriage was valid at the time of conception. That protection preserves inheritance rights, custody eligibility, and access to benefits regardless of the marriage’s legal defect.
Child support obligations also survive a void marriage. A parent cannot escape financial responsibility by arguing the marriage was never valid. Courts hold uniformly that the duty to support a child arises from the parent-child relationship, not from the validity of any marriage.
Constitutional Status of Plural Marriage
Anyone asking about the law eventually asks whether the Constitution protects the practice. It does not. The Supreme Court decided the question in Reynolds v. United States (1879), rejecting a Free Exercise challenge from a member of the Church of Jesus Christ of Latter-day Saints who argued his religion required plural marriage. The Court held that Congress cannot regulate religious belief but can regulate religious practice that violates criminal law.7Justia. Reynolds v. United States That principle, belief protected and conduct not, remains the foundation of anti-polygamy law today. Modern challenges, including litigation that followed the Supreme Court’s 2015 decision in Obergefell v. Hodges, have not changed the result. No federal court has recognized a constitutional right to polygamy.