IIRC there was one case in the U.S. involving child anime porn, but it didn't go to court, the guy pled out on a lesser charge. Allegedly because the Prosecutor wasn't sure the law prohibiting pornagraphic "images" of children would hold, and didn't want to risk setting precedent on something minor. Whereas the guy didn't want to risk the tougher sentence if it did. (or something like that)