[curryst]

> Sometimes the difference between libellous and a critical statement protecting the public is purely the difference of the statement being true or not.

Or whether the person making the statement knew that it was false at the time (or should have known). That won't protect the statement from being libelous, but it limits your maximum liability to actual damages that you can show (which in many cases is only going to be the lawyer fees; in the case of a widely repeated libelous statements, how do you determine what harm came from which sites?).

> This is not something a moderator is necessarily in a position to be able to judge

I would make that a harder statement. Moderators cannot tell whether a certain post is libelous. Even assuming that the moderator knows whether the post is factually true or not (and there are a lot of accusations where, when they come out, no one knows for sure who is telling the truth), whether it's libelous depends on whether the person in question is considered a public figure, and whether the person that posted it did enough fact checking to be deemed sufficient in attempting to prove or disprove it. The only person that can determine whether the person being defamed is a public figure, and whether the burden to verify the facts was met, is a judge with jurisdiction over the case. Anything else is just people guessing at how a judge would interpret this case, which is fraught with problems, including and up to that two judges who have jurisdiction would disagree on some facet of that.