The Democratic Alliance will formally appeal the Western Cape High Court's ruling against the party in its court battle with Cape Town Mayor Patricia De Lille.
The High Court last month set aside the DA's decision to terminate De Lille's membership for comments she made during a radio interview in April.
A full Bench found that the party's determination that she ceased to be a member was unlawful and not procedural, returning De Lille's membership, and therefore her position as mayor.
DA deputy federal council chairperson Natasha Mazzone confirmed to News24 on Monday that the party's Federal Executive decided to go ahead with an appeal, and informed the broader Federal Council of the decision at its meeting this past weekend.
"Our legal team is in the process of finalizing the documents," Mazzone said.
"The FedEx will be [deliberating] on the stalled disciplinary issues this week and charting the way forward in this regard."
Mazzone previously said following the judgment that the party's Constitution may have been misinterpreted and there was grounds for a possible appeal.
The ruling in the De Lille matter had larger implications for all the party's pending and prior disciplinary hearings dating back to at least 2015.
The High Court ruled that the DA's federal legal commission panel, appointed during its first meeting after its 2015 Congress, was improperly constituted.
The legality of disciplinary decisions taken since then involving the panel, including in De Lille's matter, has therefore been questioned.
Deputy Cape Town caucus leader JP Smith told News24 following the judgment that the caucus will consider a new motion of no confidence in De Lille as well.
However, it required legal clarity first on whether the party would appeal the judgment.
A successful appeal could eliminate the need for a new motion of no confidence, he said.
If an appeal fails, the DA would need to reconstitute its federal legal commission panel, and restart its disciplinary processes against De Lille.
De Lille meanwhile returned to her position as mayor indefinitely following the judgment, albeit with significantly less executive powers.
The City of Cape Town council stripped De Lille of most of her powers in a motion passed on May 31.
The council however may have to sit again at the end of July to vote again on the issue, after deficiencies were raised in the initial motion.