It is illegal to marry your first cousin in 25 states, legal without restrictions in 18 states and the District of Columbia, and legal only under specific conditions in seven more. There is no federal law on the question. Each state writes its own consanguinity statute, and the state where you apply for the marriage license is what decides whether the marriage is valid.
The 25 States That Ban First-Cousin Marriage
These states prohibit first-cousin marriage with no exceptions for age, counseling, or fertility:
- Arkansas
- Delaware
- Idaho
- Iowa
- Kansas
- Kentucky
- Louisiana
- Michigan
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- South Dakota
- Tennessee
- Texas
- Washington
- West Virginia
- Wyoming
Idaho’s statute simply declares that all first-cousin marriages are prohibited.1Idaho State Legislature. Idaho Code Section 32-206 – Marriages Between First Cousins Iowa classifies these marriages as void, meaning the state treats them as if they never happened.2Iowa Legislature. Iowa Code Chapter 595 – Marriage Tennessee is the newest addition, passing its ban in 2024 after previously having no restrictions.
A few of these states treat the marriage as a criminal matter as well. Texas, Oklahoma, and Arkansas include cousin marriage within the reach of their broader incest statutes, which means fines or jail time are theoretically possible. In practice, prosecutions are extremely rare and states almost always just void the marriage.
The 7 States That Allow It Only With Conditions
Seven states permit first-cousin marriage, but only when the couple meets a specific requirement, usually tied to age or the inability to have children.
Arizona. Both parties must be 65 or older. If either is younger, they need a superior court judge’s approval and proof that one of them cannot reproduce.3Arizona Legislature. Arizona Revised Statutes Title 25 – Marital and Domestic Relations 25-101
Utah. Both parties must be at least 65, or both at least 55 with a district court finding that one is unable to reproduce.4Utah Legislature. Utah Code Section 81-2-402
Illinois. Both parties must be at least 50, or either party can file a physician’s certificate with the county clerk stating they are permanently and irreversibly sterile.5Illinois General Assembly. 750 ILCS 5/212 – Prohibited Marriages
Indiana. Both parties must be at least 65. There is no fertility condition.6Indiana General Assembly. Indiana Code 31-11-1-2 – Marriage to Close Relative Prohibited, Marriages Between Cousins, Exceptions
Wisconsin. The woman must be at least 55, or either party must be permanently sterile.
Maine. First cousins must obtain a physician’s certificate of genetic counseling before marrying.7Maine State Legislature. Title 19-A, Section 701 – Prohibited Marriages, Exceptions The counseling is an informed-consent step, not a gatekeeping test, and the results do not bar the marriage.
Minnesota. First-cousin marriage is prohibited as a general rule, with an exception for marriages permitted by the established customs of aboriginal cultures.8Minnesota Office of the Revisor of Statutes. Minnesota Statutes Section 517.03 – Prohibited Civil Marriages This is the narrowest exception of any state, applying only to a specific cultural context.
Where First-Cousin Marriage Is Fully Legal
Eighteen states and the District of Columbia place no restrictions on first-cousin marriage. Cousins follow the same marriage license process as any other couple:
- Alabama
- Alaska
- California
- Colorado
- Connecticut
- Florida
- Georgia
- Hawaii
- Maryland
- Massachusetts
- New Jersey
- New Mexico
- New York
- Rhode Island
- South Carolina
- Vermont
- Virginia
- District of Columbia
Alaska’s statute only prohibits marriage between relatives closer than the fourth degree under civil law, and first cousins sit at exactly the fourth degree, placing them outside the prohibition.9Justia Law. Alaska Statutes 25.05.021 – Prohibited Marriages Georgia’s list of prohibited relationships does not include first cousins, and a 1966 state Attorney General opinion confirmed the practice is legal there.10Justia Law. Georgia Code 19-3-3 – Degrees of Relationship Within Which Marriages Are Prohibited
North Carolina also allows first-cousin marriage, with one carve-out: double first cousins, meaning people who share all four grandparents because both pairs of their parents are siblings, cannot marry. The state declares those marriages void.11North Carolina General Assembly. North Carolina General Statutes Chapter 51 – Marriage
What Happens If You Marry a Cousin in a State That Bans It
In the ban states, a first-cousin marriage is void from the moment it takes place. Void is not the same as divorced or annulled: the law treats the union as if it never existed, so there is nothing for a court to dissolve.
The practical fallout is significant. A spouse in a void marriage has no automatic inheritance rights, no standing to claim spousal benefits, and no access to the property protections married couples normally receive. If one partner dies without a will, the surviving partner is treated as an unrelated person for estate purposes.
Crossing State Lines to Marry
It would seem easy enough to drive to a state that permits the marriage, get the license there, and return home. The law anticipates this.
The Full Faith and Credit Clause of the U.S. Constitution requires states to honor many official acts from other states, but courts have not read it to force states to recognize marriages that violate their own strong public policies. The National Constitution Center has noted that states currently have no constitutional obligation to recognize disfavored types of marriage, including cousin marriages, from other states.12National Constitution Center. Article IV, Section 1 – Full Faith and Credit Clause A couple who marries legally in California can therefore find the marriage treated as void if they move to a state that bans the practice.
Several states go further with marriage evasion statutes aimed at residents who leave the state specifically to marry somewhere the prohibition does not apply. Illinois, Louisiana, Massachusetts, Vermont, and Wisconsin have adopted versions of the Uniform Marriage Evasion Act, which voids the resulting marriage as if it had been performed at home.13Social Security Administration. POMS GN 00305.155 – The Uniform Marriage Evasion Act The deciding factor courts look at is intent, specifically whether the couple left the state to get around the ban.
The result is a strange legal split. A cousin marriage can be valid in the state where it was performed and void in the state where the couple actually lives, which affects everything from joint tax filings to medical decisions in a hospital.