Approval for the extension of a Co Tyrone goldmine was based on inaccurate maps, it was claimed yesterday.
Local man William Donnelly alleged that more than 20 hectares of the site at Cavanacaw, near Omagh, were never properly assessed.
Mr Donnelly is seeking to overturn a failed legal bid to stop underground work at the operation.
Judgment was reserved following submissions at the Court of Appeal in Belfast.
In 2015 the then Environment Minister Mark H Durkan gave the green light to the extended project. Planning permission was granted for underground work at the existing mine on the basis of compliance with strict environmental conditions.
At the time Mr Durkan said these would include progressive restoration of the above-ground site to ensure the protection and enhancement of habitat over time.
But Mr Donnelly claimed there was an unauthorised removal of large quantities of rock from the site.
According to Mr Donnelly, that raised the possibility that the minister was "misinformed or even confused as to the scale of the project being approved".
In September last year a High Court judge dismissed Mr Donnelly's challenge against the minister's decision.
Issues were raised about the application being for 60 hectares, while maps and drawings submitted as part of the process allegedly covered an 81-hectare area.
Following arguments, Lord Chief Justice Sir Declan Morgan pledged to deliver judgment as soon as possible.