They found the law uvague and an infringement on the first amendment and so declared the Child Online Protection Act unconstitutional:

“It is apparent that COPA, like the Communications Decency Act before it, ‘effectively suppresses a large amount of speech that adults have a constitutional right to receive and to address to one another,’ Reno, 521 U.S. at 874, 117 S.Ct. at 2346, and thus is overbroad. For this reason, COPA violates the First Amendment,” the judges wrote. “These burdens would chill protected speech.”

I expect an appeal, but the fact is that the mechanisms are more restrictive, and less effective than filters, and as such appear to be unconstitutional, though IANAL.