The decision by Ronnie Fraser to fight back against the anti-Israel stance of the University and College Union is not just an act of considerable personal courage. It is also a hugely important political moment.

For many years, too many trade union members have stood by as their officers expended significant time and money on international "solidarity" campaigns. The honourable cause of Palestinian national self-determination has thus been swallowed up in an ideological pudding that bundles together Venezuela, Chile and Cuba within campaign groups often run by the same small number of hard-left organisations.

Mr Fraser, director of Academic Friends of Israel, has been driven to this course of action by his treatment at the hands of his fellow trade unionists. This should be a matter of deep shame to all his comrades in the UCU. The union that represents the country's intellectuals and thinkers should never have allowed itself to be drawn into this kind of fringe politics. Now it finds itself the subject of a harassment complaint under the Equality Act 2010.

As it has done so often over recent years, the trade union movement has provided the stick with which its opponents can beat it. Communities Secretary Eric Pickles was able to occupy the moral high ground when he wrote in the JC last week that the UCU was sending a "chilling message" to Jewish academics and students.

The labour movement and the party that represents it has been left flat-footed once more.

The TUC leadership has so far held the line against an all-out boycott on Israel but it will come under increasing pressure to harden its stance in the run-up to this year's Congress in September. So far Ed Miliband has been silent on the issue. He has the rest of the summer to reflect, but then he must show some leadership.