"What if relaxing the laws against "virtual child porn" results in a slew of "real" child porn being passed off as CG?" This was Ashcroft's principle argument, which the court rejected, largley because the government couldn't present any evidence that this was currently a problem. Where civil liberties are at stake, it's very hard to legislate what might happen down the road. "I don't believe in wanton free speech for all occasions and all circumstances." The court is essentially reiterating the old "shouting 'Fire!' in a crowded movie theater" model. Certain ideas might be patently offensive, but if we make it illegal to think them, we open a very dangerous Pandora's box indeed.