A landmark judgment regarding whether the state should continue to foot the bill for former president Jacob Zuma's defence costs is expected to be handed down in the North Gauteng High Court on Thursday.

The Democratic Alliance (DA) filed papers in late March, asking the High Court to set aside a 2006 agreement about legal costs Zuma incurred for his criminal prosecution that the Presidency signed.

This was after President Cyril Ramaphosa revealed that the agreement, signed by Zuma under former president Thabo Mbeki, formed the basis for the decision to continue paying for Zuma's legal fees in the spy tapes case.

Both the DA and Economic Freedom Fighters have brought applications to the High Court asking it to set aside the decisions made by the state attorney granting requests by Zuma to fund his legal costs in his criminal cases.

DA Leader Mmusi Maimane, who will attend proceedings, in a statement said that the official opposition had "fought for over a decade to ensure that Zuma has his rightful day in court".

"During this action and other actions both preceding and subsequent to the DA's action, his legal defence fees have been paid by the taxpayers of South Africa," he said.

"In respect of the DA's action, the cost has been R16-million but the real cost is probably nearer to R50-million. We approached the court in this action because we believe it was unacceptable for South African citizens to foot the bill of a private defence."