Lawyers challenging the 2008 initiative urged the Ninth U.S. Circuit Court of Appeals in San Francisco to uphold a federal judge's ruling in August that Prop. 8 violated the U.S. Constitution because its definition of marriage as the union of a man and a woman discriminated on the basis of gender and sexual orientation.

But in a nationally televised, 2 1/2-hour hearing, the three-judge appellate panel seemed intent on framing the case more narrowly before it reaches the Supreme Court.