The US Supreme Court on Tuesday let stand a law authorizing homosexual marriage in Washington, DC rejecting a challenge from anti-gay activists.
The top US court without comment turned down a petition from a group of residents seeking to put gay marriage to a city-wide referendum.
The high court decision, a blow to anti-gay marriage interests, came as another high profile case on the legal status of same-sex marriage in California, churned through the US legal system.
Earlier this month, A US federal appeals court asked California's top tribunal to help it rule on a challenge by opponents of same-sex marriages to the law in that state.
The US Ninth Circuit Court of Appeals sent the question back to California's Supreme Court, asking it to rule on whether anti gay marriage campaigners have the right to challenge a decision last year legalizing gay unions.
Supporters of so-called Prop 8 -- a 2008 referendum measure which banned gay marriage in California -- took their fight to the US federal court last month.
Gay rights activists wanted the federal court to uphold a landmark ruling in August last year that overturned a ban on homosexual weddings in California.
But the federal appeals court said Tuesday it could not decide the case, and sought advice from California on whether those bringing the action -- as opposed to California authorities -- had the legal right to do so.