Proposition 8 backers have prevailed in their appeal of a federal court order to turn over communications related to last year's successful campaign to ban gay marriage in California, the AP reported.

In a unanimous ruling released Friday, the Ninth U.S. Circuit of Appeals in San Francisco reversed Chief U.S. District Judge Vaughn Walker's order to hand over internal emails, memos and records associated with its strategy to ban gay marriage in the state.

Gay marriage backers argued in Perry v. Schwarzenegger that Proposition 8, the voter-approved measure that repealed gay marriage in California, “was only made on the grounds of animus towards same-sex couples.” A claim has denied, saying the state's restriction of marriage to heterosexual couples fosters procreation.

Lawyers for argued that making Proposition 8 discussions between top campaign officials public would violate the group's free speech rights and subject supporters to harassment. The three-judge panel agreed.

“Disclosure of internal campaign information can have a deterrent effect on the free flow of information within campaigns,” judges wrote in their 38-page ruling. “Implicit in the right to associate with others to advance one's shared political beliefs is the right to exchange ideas and formulate strategy and messages, and do so in private.”

The lawsuit was filed in May by a lesbian couple and a gay couple who would like to marry in California but were denied a license because of the ban. The gay couples are being represented by the legal team of Ted Olson and David Boies, who've argued that Proposition 8 violates the U.S. Constitution. The case is expected to go to trial on January 11 before Judge Walker in San Francisco.