Usually it is the right which gets cross whenever the EU appears to be telling Britain what to do. Now it is the impeccably left-wing university teachers' union, UCU, that is shaking its fist at the EU in a spasm of angry rejection of a European initiative. In a move that needs a Swift or an Orwell to do full justice to its cant, the UCU annual congress has endorsed a call to repudiate the European Union's widely accepted definition of antisemitism.

It is now the widely-accepted global benchmark for the tricky task of defining modern Jew-hate.

The definition declares, reasonably it might be thought, that "justifying the killing or harming of Jews in the name of an extremist view of religion" or "drawing comparisons of contemporary Israeli policy to that of the Nazis" or "allegations of Jews controlling the media " (a favourite BNP trope) or "accusing Jews of being more loyal to Israel than to the interests of their own nation" are all example of antisemitic discourse.

At first sight this is beyond parody as the trade union of professors sets itself up as a lexicographers' committee to re-write a dictionary definition it does not like.

The UCU assault on a widely accepted and useful definition of antisemitism which accepts criticism of Israel is both foolish and indeed morally repugnant. Denial of a definition of antisemitism is not the biggest challenge facing Jews today. But it shows how language and discourse are changing, as once again Jews become targets for political contempt and dislike.

Denis MacShane MP chaired the House of Commons inquiry into antisemitism and is author of "Globalising Hatred. The New Anti-Semitism" (Weidenfeld and Nicolson)