King's High School in Dunedin intends to fight a Ministry of Education ultimatum in the courts.
The school has been told to establish an enrolment scheme by next Friday, or the Ministry of Education will appoint a limited statutory manager.
The ministry's ultimatum is in response to concerns about the school's roll, which is full.
The school has permanent teaching space for 944 students but has a roll of 1035.
But a spokesperson for the board of trustees, David Booth, said there was no overcrowding at the school, with an average of 25 students per class.
Mr Booth said King's was a high-performing school that was being penalised for doing well.
He said the Ministry was concerned about empty classrooms at other Dunedin schools and was focusing on bricks and mortar.
Mr Booth said the school planned legal action to prevent the imposition of a statutory manager.
Ministry spokesperson Katrina Casey said it was disappointed the school had not taken any action to provide certainty for its future students.
Ms Casey said if the board of trustees declined to provide a draft enrolment scheme by next week, the ministry will have no choice but to step in.