Thank you Heric. That is a very big difference. It roots (for public figures) defamation in falsity, rather than in reputation. While the UK position may be over-restrictive, even though we are developing a defence of "serious reportage", my instinct is to feel that the position you set out is an encouragement to gutter debate (like the remarkable TV ad seeking to denigrate Barack Obama by hinting that he consorted with white female prostitutes).

It would seem to leave the US position that any anonymous source can accuse any politician of dishonesty, leaving the politician unable to discover who the source is and even then having to prove that like Washington he never told a lie (in his entire life).

But I still don't see that an accusation of antisemitism can be anything other than defamatory. Plainly, if an allegation of antisemitism gained ground, it would be the kiss of death in American politics, wouldn't it?

The relatively recent UK position in this area revolves around the "Motley Fool" case, which exemplifies two things. First that a person hosting and moderating a bulletin board ("operator") must disclose the identity of a poster of defamatory matter, and second that such an operator is liable for defamatory matter if not removed (which is rather like a mirror of the defence of innocent publication).