Schools, teachers and students had reasonably expected that those taking the June examinations would be treated the same as students who had sat earlier papers and handed in controlled assessments, argued Clive Sheldon QC, acting for the alliance.
The exam boards and Ofqual knew at the time of the publication of the January grades that this reasonable expectation might be disturbed but did nothing to let schools, teachers and students know that extreme changes might take place in the summer, he said.
Mr Sheldon told Lord Justice Elias and Mrs Justice Sharp at the High Court hearing that there could be no doubt that there was "grade manipulation" by the examination boards to meet Ofqual's "statistical fix" and this was an unlawful abuse of power.
More top news
Scientists believe they may have found the key to fighting HIV - and it rests in the immune system of llamas.
The United Nations has made a renewed and record-breaking global appeal, after falling well short of its last request for financial help.
It used to be the most important club on the northern variety circuit, but since Bernard Manning's death the club no longer draws the crowds