The US Supreme Court rejected on Monday a bid by a former Kentucky county official to overturn its landmark 2015 ruling legalising same-sex marriage nationwide, as the justices steered clear of the contentious case some 3-1/2 years after its conservative majority reversed abortion rights.

The court, which has a 6-3 conservative majority, turned away an appeal by Kim Davis, a former Kentucky county clerk who was sued by a gay couple after refusing to issue any marriage licences after the 2015 decision recognised a constitutional right to same-sex marriage.

Davis has said same-sex marriage conflicts with her religious beliefs as an Apostolic Christian.

She appealed after lower courts rejected her claim that the US Constitution’s First Amendment right to free exercise of religion shields her from liability in the case. Davis was ordered to pay more than US$360,000 in damages and legal fees for violating a same-sex couple’s right to marry.

The 2015 ruling in the case called Obergefell v Hodges represented a historic victory for LGBT rights in the United States. It declared that the Constitution’s guarantees of due process and equal protection under the law meant states cannot ban same-sex marriages.