Volokh discusses the Porn War.

I'm not asking whether porn is bad, or whether porn should be constitutionally protected. I'm certainly not asking whether we'd be better off in some hypothetical porn-free world (just like no sensible debate about alcohol, drug, or gun policy should ask whether we'd be better off in some hypothetical alcohol-, drug-, or gun-free world). I'm asking: How can the government's policy possibly achieve its stated goals, without creating an unprecedentedly intrusive censorship machinery, one that's far, far beyond what the Justice Department is talking about right now.