But the JC can reveal she will not face any antisemitism charges because the allegations against her pre-date a change in 2017 to Labour's rule book that created specific regulations around Jew-hate.
Instead, Ms Walker - who has repeatedly campaigned under the banner of being a black anti-Zionist Jew - is facing allegations she has been guilty of behaviour that is prejudicial to the party.
At one stage, Ms Walker walked outside to address her supporters claiming she had been refused the chance to read an opening statement in the hearing.
Reading from a printed script - suggesting she knew she would not be allowed to speak - Ms Walker told the small crowd: "Why are they so scared to hear the voice of Jackie Walker?"
One activist later said: "Even the Yorkshire Ripper was allowed to speak at his trial."
A succession of witnesses including JLM vice-chair Mike Katz were set to give evidence against the former vice-chair of Momentum during the hearing, which is expected to last two days.
But the verdict will be determined by three members of Labour's National Constitution Committee (NCC), the party's highest disciplinary body.
One of them is Russell Cartwright, a member of the Campaign For Labour Democracy who once defended Ken Livingstone over antisemitism allegations.
Another person on the panel deciding Ms Walker's fate is Ann Dyer, a longstanding Unite union activist.
She has a reputation for being independent, despite being supported by Momentum during a ballot for roles on the NCC. Ms Dyer was made the NCC's interim chair last September.
A third - likely to be the casting vote on Ms Walker's conduct - is the Communication Workers' Union's Alan Tate, who is reported to be "undecided" on the allegations.
On Tuesday morning, activists who have already been expelled from Labour spoke out in defence of Ms Walker outside the hearing venue.
Tony Greenstein - expelled by Labour last year after mocking the phrase "Final Solution" and persistently using the word "Zio" - told the crowd "Jews will be blamed" if Mr Corbyn does not go on to become prime minister.
Stan Keable - a member of the Labour Party Marxists group - also protested his innocence over his expulsion from the party for circulating an article that conflated Zionism with Nazism.
Marc Wadsworth - expelled over his behaviour towards Jewish MP Ruth Smeeth at the Chakrabarti report launch in 2016 - gave a speech attacking what he said were the use of "bourgeois courts".
A representative from the Iranian-backed Press TV channel, which was covering Ms Walker's hearing, was later spotted sitting with Mr Wadsworth in a nearby Costa Cafe.
Suspended Labour MP Chris Williamson sent a message of support that was read aloud by activist Tina Werkmann in defence of both Ms Walker and Ken Livingstone.
It said: "Let’s also remember that Jackie Walker has spent her life fighting racism, as well as being a target of it.
“She helped to spearhead the efforts to stop Nigel Farage obtaining a parliamentary platform for his bigoted credo, when he stood as a parliamentary candidate in South Thanet in 2015.
“Thank you, Jackie, for your tenacity and your bravery.”
Other activists from the fringe, pro-Corbyn Jewish Voice For Labour (JVL), including Naomi Wimbourne-Idrissi and Jenny Manson, were present on Tuesday.
Witnesses originally scheduled to speak in her support, including JVL activist Leah Levene, staged a walk-out from the hearing in protest at the refusal to let her read her supporting statement.
They claim Ms Walker is not being granted natural justice because she has been repeatedly criticised for her conduct by MPs and Jewish activists as the party dealt with her case.
Ms Walker has remained vocal during her suspension, claiming she is the victim of a "lynching".
At the weekend, she labelled veteran Labour MP Dame Margaret Hodge a member of the "white millionaire elite", calling her a "black Jew baiter."
