Zuma, 82, is fronting uMkhonto we Sizwe (MK), a new opposition party that has become a potential disrupter in the May 29 general ballot.
But electoral authorities have argued the graft-tainted politician should be barred from the race because of a 2021 contempt of court conviction.
The Constitutional Court in Johannesburg is called to decide on the matter after a lower court sided with Zuma in April.
Coming only weeks before what is expected to be the most competitive vote since the advent of democracy in 1994, the case has made some observers nervous.
Zuma’s jailing in 2021 triggered a wave of unrest, riots and looting that left more than 350 people dead.
There are fears of a repeat.
“Zuma’s supporters have threatened violence again this year should things not go their way,” said Zakhele Ndlovu, a politics lecturer at the University of KwaZulu-Natal.
A few dozen MK activists, wearing the party’s green and black colours, chanted and danced outside the court in a show of support for Zuma.
Some held signs reading “Vote MK party”.
Inside, wearing a blue suit and tie, the spectacled politician sat behind his lawyers as they made their case.
Much of the morning was spent debating a request by Zuma’s legal team that six judges recuse themselves as “tainted by bias”.
The court eventually dismissed the application, providing no motivation.
Many in the former president’s camp see the Constitutional Court as partisan.
It is the same court that in 2021 sentenced Zuma to 15 months in prison after he refused to testify to a panel investigating financial corruption and cronyism during his presidency.
And the head of that panel is now the court’s chief justice.
The case revolves around the interpretation of a constitutional norm barring anyone sentenced to more than 12 months’ imprisonment from serving in parliament.
The ban lapses five years after the sentence is completed.
The electoral commission (IEC) argued the provision applies to Zuma.
But the political veteran’s lawyers successfully contended before the electoral court that it does not, for his sentence did not allow for an appeal and was shortened by a remission.
Legal experts said it might take a few days to reach a final verdict.
Ben Winks, a lawyer specialising in constitutional law said the IEC had a strong case on appeal.”The wording of the constitution… does not talk about how long you served,” he noted. Zuma was freed on medical parole just two months into his term.
His new party came out of nowhere to become one of the main contenders in the election.
Banking on Zuma’s popularity, MK is expected to cut into the vote share of the embattled ruling African National Congress (ANC) — the ex-president’s former political home.
This could push the ANC towards a return of below 50 percent for the first time in a national vote.
Short of a parliamentary majority, it would be forced to seek coalition partners to remain in power.
The ANC is struggling in opinion polls in the context of a weak economy and allegations of corruption and mismanagement.
An Ipsos poll last month (April 2024) put it at 40.2 percent, with the liberal Democratic Alliance on 21.9 percent and the leftist Economic Freedom Fighters 11.5 percent. MK followed on 8.4 percent.
Announcing the appeal last month, the IEC said it did not intend to “involve itself in the political field of play” but sought “clarity” to “ensure free and fair elections”.
South Africans are called to elect a new parliament, which then appoints the president.
