Marrying a first cousin became illegal in Connecticut on October 1, 2025, under a new state law prohibiting such unions prospectively. Previously one of about 18 states allowing first-cousin marriages without restrictions, Connecticut joined 26 states with outright bans via HB-06918, signed June 23, 2025. Pre-existing marriages remain valid, protecting couples wed before the effective date.
Historical Context
Connecticut law long prohibited marriages between parents, grandparents, children, grandchildren, siblings, aunts, uncles, nieces, nephews, stepparents, and stepchildren, rendering them void. First cousins escaped this list until 2025, aligning the state with trends in Tennessee and others citing genetic risks like congenital defects from inbreeding. The ban targets “knowingly” entering such marriages post-October 1, 2025.
New Legal Prohibitions
HB-06918 adds first cousins to ineligible parties, expanding Conn. Gen. Stat. eligibility rules requiring age 18+, no prior marriage equivalent, and no conservatorship without consent. Violations make new first-cousin marriages unlawful, potentially voidable upon challenge, though penalties focus on prevention rather than criminalization. Same-sex or infertile couples face the same bar, unlike restricted states like Maine.
Genetic and Social Rationale
Lawmakers cited National Library of Medicine studies showing elevated risks of limb abnormalities, heart defects, premature births, and neonatal mortality in cousin offspring. Bipartisan support emphasized closing an outlier gap, with no grandfather clause beyond pre-ban validity. Critics noted rare actual cases but prioritized public health alignment.
Enforcement and Exceptions
Vital records registrars reject first-cousin applications post-ban; no divorces mandated for prior unions. Out-of-state cousin marriages hold if valid where performed, per Connecticut recognition rules. Common-law or religious ceremonies lack legal force without licenses.
Practical Implications
Couples discovering cousin ties via DNA tests post-2025 cannot wed legally, impacting benefits like inheritance or healthcare proxies. Second cousins and beyond remain eligible statewide. Legal challenges unlikely given settled interstate variances.
SOURCES:
- https://www.cga.ct.gov/2025/JFR/H/PDF/2025HB-06918-R00JUD-JFR.PDF
- https://www.cga.ct.gov/2025/sum/pdf/2025SUM00072-R01HB-06918-SUM.pdf
