The UCU has now sent out a communication to branch and local association secretaries, explaining the legal advice the union received. It seems to be in line with the interpretation of things offered on this blog yesterday.
Thus, 'the Union and its members are fully entitled to exercise their right to freedom of expression, discussion and debate by considering the pros and cons of the proposed boycott'; but 'it would... be beyond the Union's powers and unlawful for the union to call for or to implement a boycott by the Union and its members of any kind of Israeli universities and other academic institutions'. (Thanks: E.)