That hearing last April is understood to be the first of its kind in Australia.
Justice Preston went further, however, with a judgment that could set a precedent for other projects.
The mine, he found, would be «a material source of greenhouse gases and contribute to climate change». He noted the NSW government had endorsed the Paris climate agreement of cutting such pollution and «had set itself the goal of achieving net zero emissions by 2050».
Approving a new mine would be wrong because its emissions would «increase global total concentrations of greenhouse gases at a time when what is now urgently needed … is a rapid and deep decrease», Justice Preston concluded. «These dire consequences [of climate change] should be avoided.»
Mr Roberts was guarded in his assessment of the judgment, saying «these decisions are made on a case-by-case basis», adding that «the court has made its decision and that must be respected».
Labor’s climate spokesman Adam Searle, however, said the verdict «is potentially an extremely important decision» because of its incorporation of climate change in its reasoning.
«That is a new development in the law,» Mr Searle said, adding the judgment «will need to be closely considered by policymakers as well as the public».
He predicted that climate change would be a central feature of next month’s state elections. While the Berejiklian government promoted its net-zero emission plan for 2050, it «had no road map to get there», Mr Searle said. Labor would be outlining its plans during the campaign.
Matt Canavan, the Minister for Resources and Northern Australia, said Queensland’s highest court had already examined this question of emissions in relation to a proposed mine and dismissed it as grounds for rejection.
“The Queensland Supreme Court has found that ‘If the mine proceeded it would not increase the amount of global greenhouse gases or any environmental impact resulting from those gases,’» Senator Canavan said.
“This latest decision is in a lower court and in NSW,» he said, adding people «should proceed with caution» about over-interpreting it.
For its part, Gloucester Resources said it was disappointed by Friday’s decision and «would consider its next steps».
Stephen Galilee, chief executive of the NSW Minerals Council, said his organisation too would «take a close look at the judgment, including what appears to be a range of different reasons for the outcome».
«However, we don’t believe this is in any way a ‘landmark case’ given the Department of Planning had already recommended against the approval of the project,» he said.
David Morris, chief executive of the NSW Environmental Defenders Office that acted for Groundswell Gloucester, said that although the judgment was not binding, it was potentially highly influential given the status of the court and the seniority of Justice Preston.
«It can be raised in respect to any fossil fuel project in Australia,» Mr Morris said.
«The findings are really of general importance.»
‘Chain of reasoning’
Matthew Rimmer, a law professor at the Queensland University of Technology, said that Justice Preston’s judgment «was quite a remarkable decision», dealing with Indigenous, health, social and other factors as well as climate ones.
Any appellate court «will have to work through that chain of reasoning», Professor Rimmer said.
For Groundswell members, though, Friday’s decision brought great relief, apparently bringing closer an end to more than a decade of battling not only the Rocky Hill mine but also a plan by energy giant AGL to puncture the nearby valley with 330 coal seam gas wells.
AGL ditched that project three years ago last Monday after concerted opposition and a litany of errors.
«The whole legal framework of planning, environment and resources — it’s just appalling,» Julie Lyford, president of Groundswell Gloucester and a former mayor of the town, said.
«It’s about time something changed.»
Peter Hannam writes on environment issues for The Sydney Morning Herald and The Age.