The DA, on the back of a court judgement that ruled in Patricia de Lille's favour, will now move for a motion of no confidence in the embattled Cape Town mayor.
In a statement released after the Western Cape High Court ruled that the DA's termination of De Lille's membership was illegal and invalid, the party said it would not be deterred by the judgment.
It will now consider the possibility of an appeal.
"The DA notes the judgment handed down by the Western Cape High Court this morning," the party's deputy federal council chairperson Natasha Mazzone said in a statement. "It is noteworthy that the court only dealt with technical and procedural matters and did not express itself on the substantive merits of the matter. We will study the judgment and consider further legal options including the possibility of an appeal."
"We are committed to putting the people of Cape Town first and will seek to do so at every turn. The city of Cape Town caucus which Patricia de Lille led expressed that it had lost confidence in her leadership by means of a vote — twice. It stated that her leadership style was divisive, autocratic and made it difficult for councillors to carry out their duties and effectively serve the people of Cape Town and drive service delivery ... It is impossible for anyone to lead a caucus in which more than 75 percent of those people no longer have confidence in your abilities based on a number of issues."
Mazzone said any "leader with any sense of accountability" would have "done the honourable thing and resigned".
"The DA understands how confusing this time has been for the people of Cape Town. No political party enjoys having a very public and messy battle with one of its mayors. But we had no choice but to protect the highest standard of leadership expected from our executive office holders," Mazzone said.
"In contrast, the DA, no matter how hard it may be, will continue holding its public representatives to the highest standard of accountability. We will not be deterred."
Mazzone said the party will, therefore, seek to move for a motion of no confidence in De Lille.