The Court of Appeals for the 9th Circuit is an appeals court that covers basically the entire west coast of the United States within it's jurisdiction. As a result of that, it covers a lot of copyright cases and has a lot of it's own copyright jurisprudence that doesn't automatically apply in other circuits. (Notably, Oracle v. Google would have taken half the time it should have been had it not included patent claims, which moved what should have been a 9th Circuit case into Federal Circuit jurisdiction.)