The DA and President Jacob Zuma will battle it out in the High Court in Pretoria on Tuesday morning, on whether Zuma can legally delay establishing a commission of inquiry into state capture.
This was pending his legal challenge against recommendations by the former Public Protector Thuli Madonsela.
Zuma has launched a separate review application against Madonsela's recommendation that he establishes a commission of inquiry and that Chief Justice Mogoeng Mogoeng choose a judge to preside over it.
Madonsela made the recommendation in her State of Capture report into whether Zuma's friends, the controversial Gupta family, had undue influence on the executive.
The investigation was launched after former deputy minister of finance Mcebisi Jonas and former ANC MP Vytjie Mentor said they were offered Cabinet positions by the family. She also investigated Eskom tenders to Gupta owned coal company Tegeta.
Zuma argues in court papers that going ahead and establishing the inquiry, under Madonsela's conditions, would render his review application moot.
He also argues that challenging the recommendation cannot be held as him failing in his constitutional obligation to uphold the law, as it's within his "constitutional right" and it's an "honest attempt to obtain legal certainty".
Zuma said Madonsela's recommendation was unconstitutional and invalid as the constitutional powers to establish a commission of inquiry, determining the type of commission and choosing the judge, rests solely with him as president. He also suggests that someone other than a judge should oversee the commission of inquiry.
"It is now commonly accepted that commissions of inquiry are executive action and that having them presided by a member of the judiciary should be discouraged for they cross the line for what is an executive function and that which is a judicial function. The remedial action offends this line of sound legal reasoning," Zuma said.
However, South Africa's main opposition party, in its court papers, questions whether his court bid "entitles him to ignore it before a court has set it aside on review".
The DA claims Zuma is not allowed to ignore Madonsela's report and that the law is clear in such a matter. It further accuses Zuma of attempting to avoid complying with the report.
The party also opposed Zuma's counter-application in June against theirs, explaining in its recent court papers that it would only respond to this in due time and that it felt the president had not laid out a legal basis for staying the implementation of the remedial action.
The DA has also been critical of the president for his continued public utterances that he wants an inquiry to take place, while knowing the matter is halted by his court action.