A High Court decision on the proposed second campus to cater for 112 St Joseph's School pupils, on Speargrass Flat Rd, near Arrowtown, was reserved after a two-day hearing in Christchurch last week.
Ayburn Farm Estates Ltd versus the Queenstown Lakes District was heard by Justice Christine French on March 12 and 13.
Queenstown lawyer Russell Ibbotson spoke as counsel for the Roman Catholic Diocese of Dunedin. James Gardner-Hopkins, of Wellington, was counsel for the appellants, while the council was represented by lawyer Tony Ray.
Mr Ibbotson told the Queenstown Times it was an appeal on matters of law.
Ayburn Farm Estates alleged the Environment Court approval of the campus last May made three errors in law.
"They have asked the High Court to rule on whether the Environment Court in reaching its decision made an error in law and if so could that error have been material to the finding.
"If the court says there was an error of law, but it was non-material, in other words it didn't matter to the outcome, then that's the end of the matter.
"If the High Court judge said there was no error of law, then that's the end of the matter," Mr Ibbotson said.
"If the judge said there was an error and it may have been material in the court making a wrong decision, the High Court will ask the Environment Court to reconsider the particular point as to whether it would be material to its conclusion."
Mr Ibbotson said it was "quite a process" and there had not been an indication on the verdict from Justice French.
She reserved her decision and told counsel she would "endeavour to deliver it as soon as she could given the relative importance of the outcome to all parties," he said.
Diocese of Dunedin Catholic Education Office director Tony Hanning said on Friday he felt there were "no surprises" in views presented.
"The interpretation placed on the district plan, that had been behind the decision and explained by Judge Melanie Harland, of the Environment Court.
"I believe that decision was vindicated, but that's my view. The appellants no doubt would have disagreed.
"It was regarded as the orthodox view and the appellants presented a view that hasn't been tested up until now. That's my impression of it."
Mr Hanning said the diocese remained optimistic the points of law on which the approval was based in the original hearing would be upheld.
"It's a reserved decision and it's Justice French's call. It may be some time before we receive that decision."
A "very, very substantial" amount of money had been spent on legal costs over the years, Mr Hanning said.
While construction of the school would not be jeopardised by the expenditure, the timetable would have to be determined by the availability of funding, he said.
