If the panel had refused to place a hold on Walker's ruling, the supporters of Proposition 8 were prepared to seek a stay from the Supreme Court. The court is believed to be divided on the question of gay marriage, with Justice Anthony Kennedy considered a swing vote. A vote on a hold might have pushed the justices into taking an early position on the question.

"I think there are strategic reasons why even the most ardent supporter of gay marriage could opt for a stay," said Hasen, an expert on federal court stays. "The concern is that rushing things to the Supreme Court could lead to an adverse result [for supporters of gay marriage.] If this case takes another year to get to the U.S. Supreme Court, there could be more states that adopt same-sex marriage and more judicial opinions that reach that conclusion."

The Court gave no reason for its decision, but:

But it ordered Proposition 8 sponsors to address in their opening brief due Sept. 17 whether they even have the legal right to try to have the trial judge's ruling overturned. Both Brown and California Gov. Arnold Schwarzenegger, the original defendants in the case, have said they support same-sex marriage and refused to defend Proposition 8 in court.

You can read the order here.