A legal challenge over this summer's GCSE English controversy is due to begin at the High Court today.
An alliance of pupils, schools, local councils and teaching unions is pursuing action over decisions which they say left thousands of teenagers with lower than expected grades in the subject.
It is challenging a move by the AQA and Edexcel exam boards to raise the boundary needed to get a grade C between January and June, as well as what they claim was a failure by England's exams regulator Ofqual to address the situation.
The alliance claims that as a result of these decisions, an estimated 10,000 pupils who took their English GCSE exam in June missed out on a C grade, and is asking for papers taken this summer to be regraded.
Ofqual has vowed to "rigorously defend" its decisions over this summer's GCSE English results.
Speaking ahead of the hearing - which is due to last three days - Brian Lightman, general secretary of the Association of School and College Leaders (ASCL) said: "Now that we have looked at all the evidence and made final preparations for the court case, we remain certain that it is the right thing to do. We are quietly optimistic about the outcome.
"Thousands of young people in England were unfairly downgraded in June in order to compensate for mistakes made earlier in the year.
"The only fair course of action for these students is to regrade the papers."
Christine Blower, general secretary of the National Union of Teachers (NUT) said that England should have followed the lead of the Welsh Government, which, in the wake of the fiasco, order that papers be re-graded.
"It is a great shame that we find ourselves in this position," she said.
Russell Hobby, general secretary of the National Association of Head Teachers (NAHT), said: "The GCSE English debacle has affected the lives of thousands of young people whose futures have been altered by a statistical aberration.
"We hope the courts will see sense and order a regrade, thus giving those who sat the exam the result they deserve."
In a report into the fiasco, published last month, Ofqual concluded that teachers were guilty of "significantly" over-marking papers amid pressure to produce good results.
Teaching unions reacted angrily to the suggestion, with some arguing that their marking had been verified and praised by marking moderators.