South Africa's graft-tainted former president Jacob Zuma on Monday will learn whether he can legally be barred from standing as a candidate in the country's May 29 general election.
The decision by the Constitutional Court could have deep implications on the result of the imminent vote, and observers fear violent unrest if the decision goes against Zuma.
Zuma left office in 2018, dogged by corruption allegations, and was briefly jailed for contempt. He has since founded a party to challenge his successor Cyril Ramaphosa's ANC.
The ANC has won every South African election since the country became a democracy in 1994, and Zuma served as the party's fourth president between 2009 and 2018.
But his era has come to symbolise the corruption allegations haunting the former anti-apartheid movement, and electoral authorities argue that Zuma's 2021 conviction bars him from the ballot.
Zuma and his new party, named uMkhonto Wesizwe (MK) after the ANC's former armed wing, challenged that ruling, but their case will come before the top court on Monday.
In a social media post, the court said it would make a judgment at 10.00am (0800 GMT) on whether "Mr Zuma (is) disqualified from standing as a candidate for the National Assembly".
After a South African general election, the president is chosen by MPs from among their own ranks, so if Zuma is not on the ballot he could not become president.
Under section 47 of the South African constitution, anyone convicted of an offence and sentenced to 12 or more months cannot stand for office until five years after the end of the jail term.
But the court will also rule on Zuma's case that the electoral commission exceeded its authority and that a contempt of court conviction, which cannot be appealed, should not lead to a ban.
Monday's ruling could have deep and destabilising political consequences.
Ramaphosa's ANC is still expected to remain South Africa's largest party, but some polls indicate that it may struggle for the first time to win an absolute majority.
Zuma's MK does not poll well nationwide but among his native KwaZulu-Natal and among Zulus he retains support -- more than 30,000 supporters cheered him at a Soweto stadium rally on Saturday.
If his party eats into the ANC's traditional support base, Ramaphosa may be forced to negotiate a coalition after the election to ensure he is re-elected to the presidency.
Any attempt to strike Zuma from the ballot may also trigger a deadly wave of unrest. Rioting after his 2021 imprisonment left more than 350 people dead.
South Africa's respected Independent Electoral Commission says ballot papers have already been printed with Zuma's image on them, but he would be unable to sit as an MP if ineligible.
The ANC was the leading political force in the struggle of black South Africans against the former apartheid regime, and has led the country for 30 years.
But late liberation leader Nelson Mandela's party has struggled in the polls in the run up to this year's vote, dogged by corruption allegations and soaring crime and unemployment rates.
Just under a third of the workforce is unemployed and the murder rate has reached 84 a day.
But Ramaphosa's party still has a formidable nationwide electoral machine, has overseen the creation of a broad social welfare system, and many older South Africans remain loyal to its historic role.
