South Africa’s top court is hearing a challenge to the decision to allow former President Jacob Zuma to contest this month’s elections.
The electoral body originally barred Mr Zuma because of his conviction for contempt of court.
That ruling was overturned on appeal, prompting the Independent Electoral Commission (IEC) to take the case to the Constitutional Court.
Mr Zuma heads the newly formed uMkonto weSizwe (MK) party, which is challenging the ruling African National Congress (ANC), which he once led.
He has been suspended from the ANC but remains a member.
The former president has been embroiled in numerous court battles ahead of the 29 May elections.
So far, the 81-year-old and the MK have won several cases.
The MK is named after the disbanded military arm of the ANC, which wanted the courts to order it to find a new name. However, this was rejected.
Mr Zuma was president of South Africa from 2009 until 2018, when he was ousted over corruption allegations, which he has always denied.
The IEC initially barred Mr Zuma, arguing that the constitution prevented people from holding public office if convicted of a crime and sentenced to more than 12 months in prison.
Mr Zuma was sentenced to 15 months in jail in 2021 for failing to testify in a corruption investigation, though he only served three months on health grounds.
Opinion polls suggest this will be the most hotly contested election since the ANC came to power in 1994, ending decades of white-minority rule.
It is predicted to get less than 50% of the vote for the first time since then.
The MK is expected to do well in Mr Zuma’s home province of KwaZulu-Natal.