The US Supreme Court declined on Monday to take up a case filed by a New Mexico photography firm sanctioned for refusing to take a same-sex couple's wedding photos.
Elane Photography had been fined under anti-discrimination legislation after declining to offer its services for two women in 2006.
The owners of the studio had challenged their punishment in a filing to the Supreme Court, arguing their constitutionally guaranteed right to freedom of expression had been violated.
However, the Supreme Court refused to hear the case, in a decision welcomed by gay rights campaigners.
“The Supreme Court of the United States today has paved the way for robust enforcement of non-discrimination laws,” said Human Rights Campaign legal director Sarah Warbelow.
“When businesses open their doors to the public, they must abide by the law and not expect special treatment based on personal beliefs.”
The socially conservative Family Research Council voiced dismay at the ruling.
“The Supreme Court's refusal to hear and uphold the First Amendment rights of Elaine Huguenin, a wedding photographer, are deeply disturbing,” the group said.
“Does our nation's highest court really believe the price of citizenship is the surrender of conscience?”
The case had been watched closely by people on both sides of the same-sex marriage debate throughout the United States, where states are increasingly legalising gay and lesbian weddings.
An Arizona law allowing business owners to decline service to gays and lesbians on religious grounds was vetoed by Governor Jan Brewer, a Republican, in February. - Sapa-AFP