Questions have been raised over the legality of National Assembly speaker Nosiviwe Mapisa-Nqakula's decision to reject a secret ballot vote in a sitting considering the Section 89 Phala Phala report.

If the vote had been successful, President Cyril Ramaphosa could have been impeached due to the allegations.

Before the 13 December 2022 proceedings got under way, African Transformation Movement (ATM) leader Vuyolwethu Zungula and Economic Freedom Fighters MPs insisted that voting should be by secret ballot. They claimed that African National Congress (ANC) MPs had been threatened.

On Monday, lawyers for the ATM argued before a full bench of the Western Cape High Court that there was no legal basis for Mapisa-Nqakula to reject the secret ballot vote.

Arguing for the ATM, Anton Katz SC said there were grounds for a secret ballot.

"There is a general view of the toxic nature of the politics. MPs were threatened and some received death threats. How toxic must it get before the Speaker accedes?" he asked.

The full bench questioned why a secret ballot was necessary, given that the National Assembly conducts its business in the open.

Katz referred to previous judgments of the Supreme Court of Appeal and Constitutional Court, which have ruled on the issue of secret ballots.

In December, the ATM approached the court to overturn the National Assembly's decision not to continue with impeachment proceedings against Ramaphosa regarding the Phala Phala saga.

The ATM is asking the court to set aside Mapisa-Ngakula's decision.

It also asked the court to set aside the National Assembly's proceedings of 13 December, and for a declaratory order that such a vote must be by secret ballot.

Days after former spy boss Arthur Fraser laid charges against Ramaphosa, Zungula lodged a motion in terms of Section 89 of the Constitution for Ramaphosa's removal.

Mapisa-Nqakula didn't accept the initial motion, but a subsequent one was accepted.

This led to the establishment of an independent panel, chaired by former Chief Justice Sandile Ngcobo, which found that Ramaphosa had a prima facie case to answer.

This gave rise to the 13 December sitting, where the vast majority of ANC MPs voted against the motion to establish an inquiry into Phala Phala.

Five ANC MPs broke ranks in the open, roll-call vote, although Tandi Mahabehlala, who had voted in support of the motion, later indicated that she intended to toe the party line - but, by then, it was too late.