The decision was taken following the handing down by the Constitutional Court on Tuesday of detailed reasons for its Friday judgment declaring the party's earlier Free State conference invalid.
Free State ANC member Mpho Ramakatsa who, together with five other ANC members, brought the initial application to the courts, confirmed that the legal review originally threatened in a letter to the conference would now go ahead.
Ramakatsa said that several of the Free State delegates attending the national conference were not legitimate as they emerged from processes after the invalidated provincial conference in Parys, which did not include duly constituted branch meetings.
Ramakatsa said: "Our aim is to get [the conference in] Mangaung nullified … It is not a properly constituted ANC conference as some of the branch members did not come out of proper processes. We are seeking to have another national conference within six months' time."
A legal source close to the case confirmed that preparations were being made to launch an application within days. It is understood that the North West province will do likewise.
In their founding papers in the Free State High Court, Ramakatsa and his colleagues had sought the narrow relief to declare the Free State provincial conference and the decisions taken there invalid.
In writing for the Constitutional Court majority, Deputy Chief Justice Dikgang Moseneke and Justice Chris Jafta found the Free State's provincial elective conference, the executive committee elected there and any decisions and resolutions taken there "unlawful and void".
Allegations of irregularities
The judges wrote: "We emphasise that the declaration of invalidity applies only to the provincial conference. The declaratory order we make does not relate to or affect the rights of delegates who have been elected at properly constituted branch general meetings of the Free State province to serve as delegates at any other conference of the party."
It was this paragraph of the ruling that newly re-elected ANC secretary general Gwede Mantashe referred to, on Tuesday morning at a brief press conference, to reiterate that the delegates from the Free State were legitimate participants in the conference.
But it is exactly this paragraph that will form one of the cores of the court application, the Mail & Guardian understands.
The Constitutional Court found that the ANC had failed to refute allegations of irregularities – which included the creation of parallel branch structures and branch general meetings that were not properly constituted – offering only "bare", "generic" and "bald" denials.
Some party members now allege that this pattern was repeated after the disputed Parys conference, where the nomination processes and the election of delegates to Mangaung were done.
The ANC's 'bare' denials
According to one ANC member who asked to remain anonymous, the Enoch Sontonga branch in the Lejweleputswa region that he belonged to was present at the Mangaung conference but had got there after procedural irregularities.
The ANC member said: "According to the national office's audit report, we have 1 280 members in our branch that would require half that number, plus one to quorate. At the branch general meeting that elected delegates to Mangaung, there were less than 100 people."
The court found that it had to rely on the Plascon Evans precedent when adjudicating the case. Evans essentially stated that if there was a dispute of facts, the court should decide the matter by "accepting as correct" the contents of the opposing affidavit.
In several instances the court found that the ANC leadership's: "bare denials … do not rise to the level of dispute of facts. The denials are generic and were made and directed at disputing the appellants' categories of irregularities and the legal conclusion that the provincial conference was tainted with irregularities. These denials are not directed at facts that support the classes of irregularities."