The opinion written by Chief Justice John Roberts was broadly supported by seven out of the eight justices, only Justice Clarence Thomas dissented.

Roberts emphasized that public disclosure "promotes transparency and accountability in the election process to an extent other measures cannot." The ruling solely deals with whether disclosing the names of ballot petitioners violates their First Amendment rights. Roberts added that petitioners could return to the lower courts with their specific concerns.

The court agreed to hear the case after Protect Marriage Washington appealed a 9th Circuit Court of Appeals decision that ordered the release of nearly 138,000 signatures that put Referendum 71 on last fall's ballot.

Referendum 71 asked voters to accept - or reject - a domestic partnership law approved by lawmakers that gives gay couples all the rights of marriage. Voters opted to keep the law.

Led by lawyer James Bopp Jr., opponents argued in April that releasing the names would put signers at risk of harassment, reprisals and boycotts of their businesses, amounting to an unconstitutional infringement of free speech rights.

"No person should suffer harassment for participating in our political system, and the First Amendment protects citizens from intimidation resulting from compelled disclosure of their identity and beliefs and their private associations," Bopp told the court.

But Bopp failed to find an ally in even the court's most conservative justice, Antonin Scalia.

"Oh, this is such a touchy-feely, so sensitive" point of view, Scalia said as the court erupted in laughter. "You know, you can't run a democracy this way, with everybody being afraid of having his political positions known."

"I'm sorry, Justice Scalia, but the campaign manager of this initiative had his family sleep in his living room because of the threats," Bopp said.

"Well, that's bad," Scalia responded. "The threats should be moved against vigorously, but just because there can be criminal activity doesn't mean that you have to eliminate a procedure that is otherwise perfectly reasonable."

In an amicus brief filed with the court, four gay rights groups - GLAD, the Human Rights Campaign (HRC), the National Center for Lesbian Rights and the National Gay & Lesbian Task Force - argued that opponents were feigning victimization.

"Petitioners seek, through their feint of victimization, to take away one of the few defenses that lesbian and gay individuals have to defend against hostile initiatives: the use of public records to stop the fraudulent qualification of such measures in the first place, and to lobby, through personal advocacy, the people who legislate using such measures," the groups wrote.

"The Court should decline the invitation to scrap these protections based on a poorly-supported and largely fictitious tale that those who seek to deprive lesbian and gay Americans of rights are the ones being victimized."

Under Washington state law, names of people who sign petitions become public record after the Secretary of State verifies a petition, but Referendum 71 names have remained sealed pending the court's decision. State officials argue that the names should be released because signers are acting in place of lawmakers, who do not approve laws in secret.

Gay rights groups announced early in the campaign their intention to make the names public via the Internet once released by the state.

The ruling is good news for gay rights advocates who worry about the conservative leanings of the court as three cases wend their way to the Supreme Court. All of the cases involve the right of gay and lesbian couples to marry.

Two of the cases challenge the federal Defense of Marriage Act (DOMA), which blocks married gay couples from accessing federal benefits, while a third questions the constitutionality of California's gay marriage ban, Proposition 8.