So how can filtering be done?

lythander writes: Companies and parents try to do it here in the US, China does it (hamhandedly), Australia is about to trial it (and will go down in flames). From years of being against it for all the right reasons, I understand that kids shouldn't see porn, and some things are just abhorrent and should be removed (insert inflamatory child exploitation reference here). How can it be done without trampling civil liberties, without imposing one country's laws on another, etc.? This is a question for the times, where people who understand civil liberty, human rights, law enforcement on an international scale and technology must come together to seriously discuss and solve this issue before the demogogues who would use the cry, "Think of the children!" to impose their puritan views on the Net can. I was looking for serious discussion, but I came to Slashdot instead.