Hundreds of EFF supporters protested outside the East London Magistrate's Court to call for the recusal of Magistrate Twanet Olivier, who is presiding over the firearms-related case of EFF leader Julius Malema and his bodyguard, Adriaan Snyman.
Malema accused Olivier of bias and of taking a prosecutorial role during Wednesday's proceedings.
The problem started during the testimony of Samuel Kwata, an employee of audio-visual company Gearhouse, which was a service provider at the EFF's fifth-anniversary event at Sisa Dukashe Stadium in East London in 2018.
Olivier asked Kwata if he could see the firearm Malema was carrying in a video of the event.
A visibly agitated and frustrated Malema stood up during the proceedings and shouted: "She is prosecuting us now! We are being prosecuted by her!" before he sat down again.
His advocate, Laurence Hodes, SC, and his co-accused's advocate, Shane Matthews, objected.
The recusal application is scheduled to be heard in East London Regional Court on Thursday.