This year's conference of the public services union Unison (16-19 June) has a motion (no.72) from the National Executive to confirm the "economic, cultural, academic, and sporting boycott of Israel" which Unison voted through in 2007, with amendments seeking to sharpen the "shun-Israel" message.
An amendment from the Scottish region (72.01) seeks to "review" the relations which Unison has with the Israeli trade union movement, the Histadrut, as part of its general links with public service unions internationally, and to demand "a ban on imports... and until such a ban is introduced, a boycott" of products from Israeli settlements in the Occupied Territories.
At the 2007 Unison conference, a leaflet from the Communist Party of Britain advocated specifically that the general boycott policy be extended to a breaking of links with Israel's organised workers. The CPB is now pushing the issue harder.
Almost all trade unionists will agree in condemning the Israeli government's battering of Gaza. A boycott may seem like a good, easy way of expressing that condemnation.
But the bottom line argument against a boycott is that it brands all Israeli Jews (or all who do not pass some prescribed political test) as beyond talking to. In Britain, a boycott-Israel movement would, inexorably, become an anti-Jewish movement, directed against people who are likely to have close links with or a reflex identification with Israelis, i.e. Jews.
Already, in Britain, the most visible boycott activity is the pickets organised by some small anti-Israel groups at Marks and Spencers stores. Why Marks and Spencer? Because it is the High Street chain most associated with British Jews.
The main victim so far of moves for an academic boycott of Israel has been an Israeli academic, Miriam Shlesinger, who had been a leader of the Israeli section of Amnesty International, a prominent supporter of Palestinian rights - removed from the editorial board of an academic journal simply because she is an Israeli Jew.
Boycotts are necessarily crude, broad-brush tactics. There is no way that a boycott can be made a precision instrument to hit the Israeli chauvinists and help the Israeli democrats and peace campaigners.
Doesn't a boycott answer the need we all feel to "do something" in response to Israel's terrible record in the Occupied Territories?
No. At the 2007 conference the speaker from the National Executive backing the boycott motion was explicit that it did not commit the union to doing anything. It was a pure token, of no purpose... other than to give a bit of indirect encouragement to the people picketing Marks and Spencers, and make activists feel the union was "doing something".
Taken seriously, a "cultural boycott" of Israel would mean that Unison members in libraries, for example, would go through the shelves removing books by Israeli authors. That would do much more harm than good.
Active links with unions in Israel and the Occupied Territories, and active support for campaigns for Palestinian rights (which will include working with Israeli supporters of Palestinian rights) are much better service to the cause of peace and democracy in the Middle East.
Shouldn't we be helping Arab workers in Israel? But the union that has done most along those lines is the rail union RMT, which explicitly rejects a boycott of Israel. It organised a picket of the Israeli embassy to support Arab railworkers in Israel facing victimisation, as part of a campaign in which those workers have already won a reprieve. It has made links with militant workers' groups both in the Occupied Territories and in Israel. It could not have done that effectively with a boycott policy.
Doesn't the case of South Africa prove that boycotts work? No. The movement to boycott South Africa continued for more than three decades, with only the most marginal effects on the state. Apartheid did not begin to crumble until the new black-majority workers' movement and the population of the townships rose up.
And the boycott of South Africa did not have the same downside as proposals to boycott Israel. No-one saw it as a signal to shun all South Africans, because we knew that the majority within South Africa favoured the boycott.
In Israel, a boycott would contribute to strengthening the sense of being under siege in a world of enemies which is a strong element in the power of the Israeli right, and weaken those in Israel who want a just settlement with the Palestinians.
Breaking, or loosening, links with the Histadrut means writing off Israeli workers as a force for progress. Yet the Israeli people have mounted proportionately bigger demonstrations against their own government in wartime - in wars where the Israeli civilian population is to some extent under attack, too - than any other population we can think of.
Many union federations in many countries have taken nationalist stances. In every other case, trade-unionists would, as a matter of course, maintain the international union links while expressing their disagreement. Why are Israeli unions singled out for special shunning? If Arab workers in Israel are members of the Histadrut - which they are - and Palestinian unions have links with their Histadrut counterparts - which they do - shouldn't Unison have links too?
The militant boycotters - the people who put it into practice by picketing Marks and Spencer, rather than just voting for boycott as a token - insist that Palestine must be "one state", "from the river to the sea", i.e. that Israeli Jews must agree to be part of an Arab-ruled state or be conquered to make them agree.
The Executive motion disagrees. It supports a "two-states" settlement in Israel-Palestine. It also expresses "concern that the conflict has led to a growing number of anti-semitic attacks on Jewish communities living outside of Israel".
Unison members who agree with those clauses in the Executive motion should recognise that the boycott policy, and the moves to try to break Unison's links with the Histadrut, cannot help a "two-states" settlement, and - if they become more than a token - cannot but build up the anti-semitic pressure.