A U.S. federal appeals court on Tuesday ruled Proposition 8, the voter-approved ban on same-sex marriage in California, unconstitutional, paving way for the U.S. Supreme Court to rule on the issue as early as next year.According to the court document, a three-judge panel of the U.S. 9th Circuit Court of Appeals in San Francisco ruled 2-1 that Proposition 8, the 2008 ballot ban that makes only marriage between a man and a woman is valid or recognized in California, violated the U.S. Constitution.