Ofsted has won an appeal against a ruling that a damning inspection report was unfair.
The Durand Academy, which ran a school in south London and one in West Sussex, was found to be "inadequate" in 2017.
It claimed it was unable to effectively challenge the report on its performance under the watchdog's complaints process and last July the High Court ruled in its favour.
However, the Court of Appeal has now ruled in favour of Ofsted.
Giving judgment earlier, the Court of Appeal found the High Court was "wrong to conclude that Ofsted's complaints procedures are unfair in serious weakness/special measures cases".
Lord Justice Hamblen, sitting with the Master of the Rolls Sir Terence Etherton and Lord Justice Green, found there were "sufficient protections to ensure that the overall procedure is fair in the more serious cases".
He said the High Court had "erred in focusing exclusively on the complaints procedures and not considering the overall fairness of the process of inspection, evaluation and reporting".
An Ofsted spokeswoman said she was "delighted" with the judgement.
"We have always maintained that our complaints process, especially for inadequate schools, is fair and rigorous," she said.
"All judgements of inadequate are subject to additional scrutiny and an extended quality assurance process before being finalised.
"Schools are engaged in this process and have the opportunity to challenge the inspection findings."
The Durand Academy Trust consisted of an infant and junior school in Stockwell, south London and a boarding school in Midhurst, West Sussex.
It received £17m from the government to set up the school for weekly boarders in 2014, but it was announced last year that funding would be withdrawn.
The London schools have since been taken over by another educational trust.