Eugene Volokh does an excellent job explaining why John Ashcroft's "obsenity crackdown" is doomed to failure, tyrrany, or both.

Not that that's stopped the "war on drugs".

I do wonder, however: Could a P2P service be hit with obscenity charges more easily than copyright violation? "Substantial noninfringing use" is a copyright defense, not necessarily one for obscenity--- but then, I'm not sure there's a "contributory obscenity" charge anyway.