A Christian official has refused to issue marriage licences to same-sex couples in Kentucky despite exhausting all of her legal options.
A district judge could now hold Rowan County Clerk Kim Davis in contempt, which can carry steep fines or jail time.
She had argued that her faith prevented her from carrying out her duty.
But the US Supreme Court rejected her argument on Monday and ordered her to grant licences.
Since the court legalized gay marriage nationwide two months ago, Ms Davis has refused to issue any marriage licences to anyone.
The American Civil Liberties Union sued her on behalf of four couples, two gay and two heterosexual.