The Free State High Court in Bloemfontein has ordered that the ANC Free State's elective conference cannot go ahead until branch general meetings, which were declared unlawful, are rerun.
The court ruled that several branches across four regions of the province were "irregular, unlawful, unconstitutional and in breach of ANC constitution".
However, the judgment was not unanimous. In the majority judgment, the two judges said the elective conference scheduled for this weekend in Parys should be postponed.
"The provincial conference of ANC Free State scheduled for 1 to 3 December 2017 will be a nullity and cannot be held until the fore said meetings have been held in a lawful manner and in accordance with the constitution of the ANC," the judgment reads.
Disgruntled ANC members had taken the province to court, claiming that branch general meetings ahead of the fiercely contested elective conference were flawed.
Long standing Free State chairperson Ace Magashule is expected to be challenged for the position by his deputy Thabo Manyoni.