A High Court judge has refused to grant a judicial review of a decision to merge two school academies.
Parent Amie Falconer sought the action against the education secretary's approval in May for Trafalgar College and Great Yarmouth Charter Academy (GYCA) in Norfolk to merge.
Lawyers said he ignored legal principle and the department's own guidance on community opposition to the merger.
But Mr Justice Walker said the contest was "fundamentally misconceived".
The Inspiration Trust applied to the Secretary of State for Education, Damian Hinds, to bring together GYCA and Trafalgar College in November 2017, following a public consultation.
In May, the minister approved the merger plans which come into force from September.
He also approved in principle for Trafalgar College, a free school, to become "a school with a Christian character" like GYCA.
The case brought by Ms Falcolner also contested the minister's approval for the religious re-designation which was said to be legally flawed.
But ruling at London's High Court on Tuesday, Mr Justice Walker said: "After hearing extensive oral submissions this morning I have reached a conclusion that there is no such sufficiently arguable case as would justify the grant of permission [for judicial review]."
Ms Falconer has a child at Trafalgar and a second requiring a secondary school place.
After the hearing she said she was "extremely disappointed with the decision and will now be contemplating whether to move out of town to to get my [second] child into a good school".
Her lawyer Dan Rosenberg said they would not appeal.
"Lots of people locally will be disappointed by this result for which the court acknowledged there was little support for the changes," he added.
Inspiration Trust chief executive Dame Rachel de Souza said: "This is an important change for pupils in Great Yarmouth, and we are pleased that the decision of the court today will allow us and our families to proceed with certainty."
The hearing was attended by a member of the Department for Education who said he could not comment on the outcome.
Great Yarmouth councillor Mike Smith said he was extremely "disappointed for the parents and town of Great Yarmouth which now only has one secondary school".
GYCA has been controversial since it was set up in 2017 because of its strict rules and leadership.
Trafalgar College was founded by the Inspiration Trust on Thamesfield Way in Great Yarmouth in 2016 with about 150 pupils.