Yes, it is illegal to marry your first cousin in Washington state under current law. RCW 26.04.020 explicitly prohibits marriages between parties nearer of kin than second cousins, classifying first-cousin unions as void from inception.
Statutory Prohibitions
Washington Revised Code § 26.04.020(1)(b) bans marriages where relatives are closer than second cousins, computed by civil law rules—first cousins fall squarely within this restriction. The statute lists additional bans on sibling, parent-child, grandparent-grandchild, aunt/uncle-niece/nephew unions, but cousin proximity is independently prohibited. No exceptions exist for age, fertility, or genetic counseling, unlike some states.
Recognition of Out-of-State Marriages
Marriages valid elsewhere are recognized in Washington only if not prohibited under RCW 26.04.020(3)—first-cousin marriages from permissive states (e.g., California, New York) remain invalid here. This prevents residents from circumventing local law via destination weddings.
Related Restrictions
Cohabitation and sexual relations between first cousins are legal; a prior criminalization was repealed decades ago. Second cousins and more distant relations face no marriage barriers. Adoption does not alter consanguinity rules.
| Relation | Marriage Legal? | Out-of-State Valid? | Cohabitation Legal? |
|---|---|---|---|
| First Cousin | No | No | Yes |
| Second Cousin | Yes | Yes | Yes |
| Sibling | No | No | Yes |
| Aunt/Uncle-Niece | No | No | Yes |
Penalties and Enforcement
Attempting a prohibited marriage renders it void ab initio—no dissolution needed, but records may require correction via court order. Bigamy charges (Class C felony) could apply if unaware of invalidity during subsequent unions. County auditors reject cousin applications upfront.
Historical and National Context
Washington aligns with 25 states banning first-cousin marriage, prioritizing genetic risk concerns despite varying scientific consensus. No 2026 legislative changes noted; reforms would need RCW amendment.
SOURCES :
- https://www.avvo.com/legal-answers/can-my-cousin-and-i-live-together-in-the-state-of–4963302.html
- https://en.wikipedia.org/wiki/Cousin_marriage_law_in_the_United_States
