Unison was formed in 1993 when manual union NUPE, white- collar workers in NALGO and COHSE's health-service workers joined forces. The organisations merged centrally, but a hard core of branches, particularly in local government, are resisting local unity.
Ron Greig, secretary of the former NUPE branch at Hammersmith and Fulham LBC, this week threatened to take Unison to the High Court over its branch merger policy.
The dispute centres on how Unison branch respresentatives will be paid. NUPE branch secretaries and stewards currently receive a guaranteed commission for their work, which many rely on to supplement low wages.
Both Mr Greig and Unison have opinions from QCs about whether the policy broke union rules when it was introduced.
Mr Greig told LGC unless Unison withdraws the policy he will take legal action.
Mr Greig claims to have the financial backing of the Commission for Trade Union Members Rights to pursue his case, which he outlined to Unison in May this year.
Unison national secretary Phil Lenton said the issue of branch commissions is irrelevant because complete merger will mean there will be no ex-NUPE branches left in 1997.
He said the union will go ahead with its merger policy. 'Unison is confident with the decision it's taken,' he said.
But Mr Lenton conceded that 75% of Unison's local government branches in London have yet to join forces and other large and traditionally wealthy branches in Yorkshire, Middlesbrough, the South East and the North West are still resisting merger.
Mr Greig says resistance from former NUPE activists comes from a fear that they will be sidelined by more vocal former NALGO activists. 'We feel our members would be in a worse position after merger,' he said.
Other branches are resisting merger because of political differences, reluctance to share funds, and disagreements over the representation of women and low paid workers.