Five new members of the Labour Party have won a High Court battle over their legal right to vote in the forthcoming leadership election.
The case was triggered by an NEC decision that full members would not be able to vote unless they had at least six months' continuous membership up to July 12.
The Labour Party and its general secretary, Iain McNicol, had argued the July 12 "freeze date" was allowed under party rules and there had been no contractual breach or misrepresentation.
They have said they will appeal Monday's High Court ruling.
But Mr Justice Hickinbottom ruled that refusing the claimants the vote "would be unlawful as in breach of contract".
"It was the common understanding, as reflected in the rule book, that, if they joined the party prior to the election process commencing, as new members they would be entitled to vote in any leadership contest".
Mr Hickinbottom added that was the basis upon which each claimant joined the party, and the basis of their contract with it.
To gain the right to vote in the leadership contest, members and non-members were required to:
become "registered supporters" between July 18 and 20
pay an additional fee of £25
The five Labour supporters who brought the case are Christine Evangelou, Rev Edward Leir, Hannah Fordham, Chris Granger and "FM", a new member aged under 18.
They have been crowdfunded and are seeking to raise £40,000 to cover their legal costs.
Reacting to the ruling, Mr Leir, one of the claimants, said: "I am deeply grateful for the support of so many: the donations of over 1,700 people to support the substantial costs in taking this action for democracy."
Solicitor: "It's about their right to vote"
Kate Harrison, solicitor for the claimants, said her clients "very much wanted to participate in the Labour Party democratic process".
She said that the legal action was not about the impact on the leadership election, adding "it's about their (the claimant's) right to vote".
"I'm proud to be part of a country, a court system, a democracy, that takes the right to vote very seriously."
The Labour Party was given permission to appeal to the Court of Appeal which could be heard later this week.
A Labour spokesman said: "It is right that the Labour Party seeks to defend vigorously decisions of the National Executive Committee in this matter, and we will now study this judgment carefully."
How have the leadership candidates reacted?
Owen Smith told ITV News he was "pleased we're got so many people taking part in this election".
"It's a brilliant democratic exercise by the Labour Party, adding "we're just need to get on with it and get to the end of this process".
Jeremy Corbyn is yet to comment on the ruling but John McDonnell, who chairs Mr Corbyn's leadership campaign, has called on the party to rule out mounting a legal challenge to the decision.
He told ITV News: "They'll be using members' money to deny members the right to vote."
"Why can't we just rely on the sound common sense of our members to elect the leader they want," the shadow chancellor added.
He also urged Mr Smith to call on the party to rule out mounting a legal challenge to the decision.
Unions react to the ruling
Aslef: Mick Whelan, leader of the train drivers' union, which is affiliated to Labour, said: "This is a victory for democracy, and a victory for common sense.
TSSA: Manuel Cortes, leader of the rail union, criticised Labour's decision to mount an appeal as a "needless waste of money", and called on Mr Smith to stand down to avoid a "divisive contest".
The result of the contest between Mr Corbyn and Owen Smith is due on September 24 following a postal ballot of members, affiliates and registered supporters.