There is an opportunity, as you know, for departments to pre-screen it, so my guess is that, if a department thought an ad campaign might violate one of the principles, they would give it to ASC to pre-screen it, and ASC would provide them advice.
If they didn't make the requisite changes, then presumably ASC would deny them the right to broadcast that campaign, although I haven't been able to find the details. It's a very important question you ask. I don't know what lever the ASC has over the government—which is your question, I think. I read in one transcript from somebody there that they would tell the government, but I'm not sure what that means.