In a major twist to the oft-delayed Jacob Zuma corruption case, Pietermaritzburg High Court Judge Piet Koen has invited arguments from the State and defence as to whether he should continue to preside over the former president's trial.

"The integrity of the trial must be beyond any criticism or reproach. It is my task to ensure that it meets that expectation," Koen stated in a brief ruling delivered on Wednesday morning.

The judge then adjourned Zuma and French arms company Thales' trial to 30 January 2023.

His self-initiated invitation for submissions on his potential recusal came after Zuma's lawyers asked that he make a decision on whether the prosecutor, Billy Downer, should continue to participate in the case – given that the former president had initiated a private prosecution against him and News24 journalist Karyn Maughan for allegedly violating the National Prosecuting Authority Act.

In a letter sent to Koen on Sunday, Zuma's attorney, Bethuell Thusini, stated that the former president objected "to any further involvement of Adv Downer in this matter [the corruption trial]" as Downer is "Accused 1 in the ongoing private criminal prosecution in which our client [Zuma] is the prosecutor".

"He [Downer] is therefore ethically and professionally bound to recuse himself as he is clearly conflicted," Thusini said, before adding that "(f)or now, we leave that issue in the hands of the court to regulate in the exercise of its own management of the proper administration of justice".

Koen had on Monday pointed out that he had previously addressed the subject matter of Zuma's criminal complaint against Downer in his ruling on his "special plea" application, where he dismissed the 14 grounds upon which Zuma contended that Downer lacked the "title" to prosecute him.

Those grounds included Zuma's claims that Downer had criminally violated the NPA Act by allowing court papers, containing a note from one of his military doctors, to be provided to Maughan.

Maughan had received the disputed court papers from advocate Andrew Breitenbach SC, who was acting for the NPA at the time.

Zuma contended that his private medical information was "leaked" by Downer, despite the fact that he failed to claim confidentiality when his lawyers filed the disputed letter in court.

Koen found that the letter was submitted to Downer "without any specific restrictions as regards confidentiality".

The judge held that the letter was vague and general, and did not disclose anything that could be said to amount to "an actionable violation of Mr Zuma's rights".

On Monday, Koen appeared concerned that the findings he had made on this issue, which he stressed at the time could still be the subject of more intensive investigation, might impact perceptions about his ability to determine whether Downer should be required to step down.

While the judge had initially invited the parties to address any written submission they "may wish to place before me in regard to my possible recusal" by 22 October, he has now extended that deadline to 3 November.

He also adjourned Zuma's trial, so that he could decide on the issue.

Koen added that, upon careful reflection, he had "concluded" that the issue of his continued involvement as presiding judge in the trial needed to be addressed.

While he appreciated that the adjournment would take up time, Koen said the delay, and the fact that the trial would not continue on its mooted resumption date of 7 November, was "inevitable and required in the interest of justice".

On Friday, Zuma filed a fresh appeal application, to force Downer's removal, in the Constitutional Court through a so-called "special plea".

The NPA is expected to oppose this latest appeal attempt, which Downer on Monday slammed as a further continuation of Zuma's so-called "Stalingrad" litigation strategy. 

The former president continues to argue that – should he successfully challenge Downer's title to prosecute him – he will be entitled to an acquittal on charges that he received over R4-million in gratification from his former financial advisor, Schabir Shaik, in exchange for using his position to further Shaik's business interests.

Zuma also stands accused of accepting a R500 000-a-year bribe from Thales, in exchange for his "political protection" from a potential investigation into South Africa's multibillion-rand arms deal.

On Monday, Downer contended that the convoluted and protracted way that Zuma had chosen to pursue his failed challenges to Koen's decision – including demanding that the Constitutional Court force the Supreme Court of Appeal to hear an appeal that they had outright dismissed – was aimed at preventing the apex court from making a final, binding ruling on the case.

Downer pointed out that, in his latest Constitutional Court application, Zuma did not ask the apex court to make a final ruling on his special plea case, but instead again demanded that the case be referred back to the Supreme Court of Appeal.

He further rejected Zuma's argument that he should "step aside" because of the private prosecution launched against him and Maughan.

"The mere fact of an attack cannot be sufficient grounds to require that prosecutors then willy-nilly withdraw from those cases and get other people to come and do their work for them," he said. 

"It doesn't work like that. And were it so, our system of justice would be in a sorry state."

The Jacob Zuma Foundation welcomed Koen's decision to postpone the matter to next year.  

It said: "The ruling shows that there is still so much hope for the South African judiciary."