Legal arguments were heard from both sides in the High Court on Tuesday. Mr Corbyn is facing a leadership challenge from former work and pensions spokesman Owen Smith, who – under the party’s rules – had to win the support of 20% of its MPs and MEPs to trigger a contest.
In the end, he secured 162 nominations after the other potential challenger Angela Eagle, who also initially passed the threshold for nominations, withdrew from the race.
At a highly-charged meeting earlier this month, Labour’s National Executive Committee decided that, as an incumbent, Mr Corbyn was entitled to a place on the ballot paper without having to go through the same process.
Mr Corbyn lost a motion of no confidence in his leadership last month. In the vote, which was not binding on him, 172 out of Labour’s 231 MPs opposed Mr Corbyn while 40 voted in his favour.
However, the Labour leader retains the support of many party members and activists who will vote in the election, leadership the outcome of which is scheduled to be announced on 24 September.
The legal challenge was brought by Mr Foster, who unsuccessfully stood as a Labour candidate at last year’s general election in the Cornish seat of Camborne and Redruth, coming second to the Conservatives.
Speaking ahead of the judgement, Mr Smith said he thought Mr Corbyn should be on the leadership ballot, and he was “hopeful and confident” that the NEC’s decision would not be overturned.
“We’re a political party and judges shouldn’t be interfering in what we decide,” he told BBC News.
Asked if he would encourage Labour MPs to nominate Mr Corbyn for the sake of a contest, if the judge ruled he should not automatically be on the ballot, Mr Smith said he would like a contest to “win the arguments” against Mr Corbyn, but added: “It’s not for me to tell them what to do.”