I think it depends on the goal of censorship. If you're trying to prevent a site (or service or group) reaching a certainly level of mass use then censorship de

I think it depends on the goal of censorship. If you're trying to prevent a site (or service or group) reaching a certainly level of mass use then censorship definitely can work. There are a large number of piracy sites blocked in the UK by court order. The blocks are trivial to get round but they are probably effective for a good proportion of UK users. But if the goal of censorship is to completely prevent a leaked fact from being communicated - that's much harder (and I'll say it's practically impossible after a certain point).