SB 6239 - 2011-12 amended RCW 26.04.010 to legalize same-sex marriage by replacing gendered terms with gender-neutral language. The law, meant to take effect on June 7, 2012, was delayed by Referendum 74 which put the issue to voters who affirmed the legislation. The law went into effect on December 6, 2012.
Same-sex marriage was further protected by the US Supreme Court in OBERGEFELL v. HODGES on June 26, 2015, under the Due Process and Equal Protection Clauses of the Fourteenth Amendment.
The 117th US Congress legislated additional protections in H.R.8404, the Respect for Marriage Act, on December 13, 2022, mandating all states recognize any public act, record, or judicial proceeding pertaining to marriage in any other state; enforceable by the Attorney General and subject to injunctive and declaratory relief.