A former chairman of Ukip in Scotland is taking his party to court over a 100-year suspension that was imposed on him for speaking to the media.
Paul Henke will challenge the ban at a court hearing in London on Tuesday and seek damages of at least £3000.
Ukip, the anti-Europe anti-immigration party led by Nigel Farage, has enjoyed electoral success in England but is in the middle of a damaging civil war in Scotland.
The row reached its peak in the party's internal selection for May's European election, during which six of the nine shortlisted candidates resigned.
The six rebels - including the then Scottish party leader, Lord Monckton - quit believing that a trio of party activists was planning a coup.
However, despite the candidates pulling out before the ballot papers were sent out, Ukip pushed ahead with a vote that was won by David Coburn.
Farage fired Monckton, whose dismissal was followed by Mike Scott-Hayward resigning as chairman in protest at the treatment of the Scottish leader.
The farce continued when 10 Ukip Scotland members signed a complaint against Coburn, whom it was alleged had made various false statements.
One of the signatories was Henke, a 63-year-old thriller writer, who told the Sunday Herald at the time: "I expect the complaint to be investigated properly. I believe Ukip to be an up-front party run by honourable people. We should have honourable people as candidates."
Henke's quote prompted Ukip's national chairman, Steve Crowther, to suspend him from the party for 100 years.
Crowther stated: "As a signatory of the complaint against our Scottish candidate which has been passed to the Sunday Herald, and having given your opinion on that subject to the Sunday Herald last week, you have brought the party into disrepute, and appear to be engaged in deliberately sabotaging our election campaign in Scotland."
Henke's court action seeks £3000 in ordinary damages for negligence and breach of natural justice, plus £1,000 in exemplary damages, as well as costs.
It is understood Henke will be represented by lawyers in the Central London County Court this week.
A senior Ukip Scotland source said: "The 100-year suspension was a hasty, ill-judged and maladroit device to prevent Paul from attending the party conference at the end of the month. Ukip should do the decent thing and abandon its baseless complaint against Paul."
The legal action comes after Monckton warned Crowther in a letter that "loonies, fruitcakes and out-of-the-closet racists" were now in the ascendancy in Ukip Scotland.
After Monckton was fired, Misty Thackeray became interim chairman of the party north of the Border.
Thackeray attracted immediate criticism after it emerged he once said Glasgow City Council was for "gays, Catholics [and] communists".
SNP MEP Alyn Smith said: "This is further evidence of the complete disarray at the heart of Ukip that has left them completely irrelevant in Scottish politics."
Maggie Chapman, the Scottish Greens' lead candidate for the European election, said: "Sunlight is a great disinfectant and we can only hope that continued exposure of this bizarre bunch of amateurs keeps Scottish politics free of them.
"There's a Scottish MEP seat up for grabs in May and we have a great chance to reject this ramshackle set of squabblers."
Ukip did not respond to an email request for comment.