When Planning Minister Anthony Roberts intervened a year ago to give a coal miner the unusual right to challenge its project's refusal in court, neither would have countenanced Friday's outcome.

Instead of settling the future of Gloucester Resources' controversial Rocky Hill coal mine near Gloucester, the NSW Land and Environment Court just cast a cloud over coal mining in general.

Sunset for Australia's coal industry?: court judgment links coal and its global-warming emissions to reject a mine proposal for the first time in Australia. Credit:BHP Billiton

The miner had thought it was merely challenging the Department of Planning's rejection of the mine's impact on visual amenity in the bucolic valley around Gloucester.

Instead, the Environmental Defenders Office, acting for residents opposed to the mine, grabbed the opportunity to join the appeal.