It has done that by voting for a resolution to boycott Israeli universities. This has happened before, of course, but on the last occasion - in May 2005 in the old AUT - the decision was later overturned. The UCU congress has now reaffirmed it. In the light of legal advice, the UCU leadership did immediately declare the vote void. Nonetheless, this cannot undo the fact that the representative body of British university and college staff is now on record as wanting to boycott Israeli academics, if (but for the law restraining them) they only could - while they have no desire to boycott any other academics in the world whatsoever. Furthermore, UCU general secretary Sally Hunt made a point of putting it on the record that she thought it was good that they have been able to have the debate of which this was the outcome.
I've already written enough on the substantive issue involved here and I don't intend to repeat what I've said before (for some representative posts, see the following: 1, 2, 3, 4, 5, 6). But members of the union can no longer disguise from themselves what it now publicly stands for in this matter. It might be said that the decision doesn't reflect the views of the membership at large but only those of activists who have hijacked the union's representative bodies, and this may well be true. But if a minority continue to be able to get their views accepted at the UCU congress, it is because the UCU membership is willing to countenance their doing so, for whatever combination of reasons. UCU members, consequently, are members of a union that is content to discriminate against academics of one nationality only - the academics of Israel. Those of them who remain complacently undisturbed by this and inactive in the face of it bear a responsibility for it.