Despite a series of community protests, the council decided that Croxteth comprehensive should close next year – citing the fact a third of desks are empty and it is the poor relation in terms of results.
St John Bosco school will also be refurbished and De La Salle Catholic college will be turned into a £20m Catholic boys academy.
Last night, Andrew Lockley, Head of Irwin Mitchell’s public law department, said: "The unity of pupils, parents and school in opposing the closure proposals is impressive."
He added: "This is something they care deeply about, and shows the strength of feeling in the community about this issue."
Headteacher Richard Baker was among community members calling for the council to abandon its closure plans and instead back an alternative "cradle-to- grave" campus proposal. This would see the comprehensive become a trust school backed by businesses, Liverpool John Moores university and feeder primaries.
Last night, Mr Baker said he was "optimistic of a successful outcome" at the High Court.
Liverpool council insists the school "did not have the capacity to improve" and its "robust" consultation was backed by the Local Government Ombudsman.
