Conservation group Forest and Bird is appealing against an Environment Court decision on mining on the West Coast's Denniston Plateau.
Last week, Conservation Minister Nick Smith gave Bathurst Resources access to Department of Conservation land, but the company still requires a resource consent before it can begin work.
In its interim decision in April this year, the Environment Court signalled it would rule in favour allowing Bathurst consents to mine - as long as it had more clarity on issues such as rehabilitation of the conservation land.
That has been appealed by Forest and Bird on a number of grounds, including the weighting the court gave to Bathurst spending $22 million on pest control.
Another appeal is being heard at the same time regarding the Environment Court's decision not to consider the impact of a neighbouring mine planned by Solid Energy.
At the Christchurch High Court on Monday, the lawyer for Forest and Bird said the Environment Court should have considered the cumulative impact of both mines on the Denniston Plateau.
However, Justice Fogarty reminded its lawyer that Solid Energy's mining licence was granted 23 years ago and an argument could be made that the mine might never go ahead.
Bathurst Resources said Solid Energy's mine has no resource consent. It said even if it wanted to mine the area, it couldn't - because there is no water available and that without it, mining is impossible.
The hearing is set down for three days.
Meanwhile, papers released last week show that Dr Smith went against his officials' advice in giving Bathurst Resources access to the area.
The papers said mining would have a major impact on many rare and endangered species, including the great spotted kiwi.
The Bathurst mine would be New Zealand's second largest mine.
