On 26 October the RMT voted to reverse its 2003 decision to affiliate to the Scottish Socialist Party.
The decision was another knock-on effect from the destructive decision of former SSP convenor Tommy Sheridan to pursue his own personal success in a libel case against the News of the World at the expense of splitting the SSP.
John Milligan, a leading figure in the RMT in Scotland, was close to Sheridan in the row in the SSP about the libel case. He attended the SSP conference on 7-8 October, after Sheridan had split away, but announced there that the RMT was "consulting" its Scottish membership about whether to remain affiliated.
The Scottish regional committee of the RMT then voted seven-to-five to disaffiliate, and the RMT national executive felt it had no choice but to ratify that decision.
Back in 2003, Workers' Liberty and some other RMT activists who supported the RMT's decision to affiliate to the SSP argued that it should be taken by a ballot of all the RMT's Scottish members rather than by a small committee. The same holds for the decision to disaffiliate. Involving all the union members in the political decisions takes more time and effort, but it gives the decisions more weight and reality, it creates a closer connection between "politics" and the working-class realities on the ground, and it makes the decisions more stable.
The upshot now is that, after a series of decisions all taken democratically according to the rule-book, but mostly by fairly small meetings without the mass of the members much involved, the RMT finds itself politically stranded.
It had been edged towards disaffiliation from the Labour Party in the run-up to 2003, with its level of affiliation being cut down to a token number. The New Labour machine seized on the SSP affiliation as an opportunity to rid itself of the RMT's critical voice.
Outside Scotland, the RMT did not work coherently towards establishing any alternative working-class political voice after 2003. It has sponsored one socialist local government candidate - Janine Booth, Socialist Unity candidate for Hackney Central in 2006, and an RMT activist - but, in England, that is all.
It has an active parliamentary group at Westminster, led by Labour MP John McDonnell, but in the Welsh Assembly and Scottish Parliament it has developed parliamentary groups involving Plaid Cymru and Scottish National Party members.
To some degree, before 2003, the RMT was politically effective as an active left-wing force spurring on other unions within the Labour Party. After 2003, again to some degree, the RMT was doing something effective to help create a working-class socialist voice outside the Labour Party, throught its affiliation to the SSP.
Now the RMT has neither one nor the other. Instead of taking part in any concerted attempt to win authentic working-class political representation - even a limited one - it has a series of connections with individual politicians who are, more or less, "friends of labour".
The most positive things about the RMT's current political activity are its support for John McDonnell's campaign for Labour leader, to replace Tony Blair, and its affiliation to the Labour Representation Committee. It is more urgent now to build on those things.
The RMT's rule 23/25, adopted in 2003, states: "That this Union shall affiliate to the Labour Party". And now the formal grounds for disaffiliation have lapsed. RMT should rally the support of other unions to challenge New Labour to concede reaffiliation and enable RMT to give full weight to its support for McDonnell.