A federal appeals court in California on Thursday ruled against releasing the video of the 2010 trial that resulted in declaring Proposition 8, California's gay marriage ban, unconstitutional.

The three-judge panel of the U.S. Ninth Circuit Court of Appeals said the video from the 12-day trial should remain sealed because defenders had been promised by the trial judge that it would be used for internal purposes only.

“The trial judge on several occasions unequivocally promised that the recording of the trial would be used only in chambers and not publicly broadcast,” the court said.

Last year, U.S. District Court Judge Ware ruled that “No compelling reasons exist for continued sealing of the digital recording of the trial.”

Protect Marriage, the coalition of mostly religious groups that sponsored Proposition 8, appealed the decision. The group's lawyers argued that releasing the recording would put defense witnesses at risk of harassment from opponents of the constitutional amendment which overruled a 2008 California Supreme Court decision that legalized gay marriage in the state.

Gay rights advocates called the decision “disappointing.”

“The court's decision to keep the people from seeing this public record of one of the most important trials in American history is extremely disappointing,” Kate Kendell, executive director of the National Center for Lesbian Rights, said in a statement. “As those lucky enough to have watched the trial saw, the defenders of Prop 8 were unable to offer a shred of evidence to support it, while the plaintiffs presented a mountain of compelling reasons to strike down this unjust and damaging law. The public deserves the same chance to see the facts for themselves.”