> No; you publish it, and the most the government can do is stop you from repeating it and punish you for having done so.

Soooo.... if I approach a US tv network with an ad that explicitly shows naked people doing cocaine, and carries the message that drugs are amazing, and ask for it to be scheduled during the kids tv peak slot, the networks are going to say "Hey, cool, yeah we'll do that"?

This seems very unlikely to me. It seems much more likely their internal compliance departments will look at it and say "Nope". So much for "you publish it".

Because that's basically what's happened here - the UK networks have outsourced checks on advertising to a third party they own, which itself gets its advertising code of conduct from an industry association the networks are part of. The third party makes decisions about whether an ad is OK. If it's not OK then the networks won't usually want to air it.