Activists and residents fighting against a proposed coalmine in central New South Wales are hoping last week’s historic judgment in the Rocky Hill case will sway the state’s Independent Planning Commission to reject the project.

The NSW land and environment court ruled last week Gloucester Resources’ Rocky Hill coalmine in the state’s Hunter Valley should not go ahead, in part because of its social impact on the town of Gloucester and because a new coalmine was not compatible with Australia’s commitments under the Paris agreement.

The planning commission has been considering plans by the South Korean company Kepco for an open-cut mine in the Bylong Valley, north-east of Mudgee.

Late last year, the NSW department of environment and planning recommended the development be approved subject to strict conditions and referred it to the commission, which is due to make its decision soon.

The proposed mine has been debated by farmers, environmentalists and residents, who have voiced concerns about the social impact, the greenhouse gas emissions from a new coal development, and also whether rejecting the mine could hurt employment in the region.

The Rocky Hill decision was a “fantastic shot in the arm for us”, said Phill Kennedy, a farmer who lives in the Bylong Valley. “The Rocky Hill proposal was minuscule compared to Bylong, which is five times the size in terms of the emissions.”

Lawyers who acted in the Rocky Hill case for community group Groundswell Gloucester said the Bylong Valley development had similarities to their case.

In his judgment, Chief Judge Brian Preston said a new open cut coalmine in the Gloucester Valley “would be in the wrong place at the wrong time”.

David Morris, the chief executive of NSW Environmental Defenders Office, which acted on behalf of Groundswell Gloucester, said there were a number of proposed mines being assessed in the state that “should now logically follow the approach outlined by Chief Judge Preston”.

“The one to my mind that is the closest comparison to the Gloucester project is the Bylong Valley mine,” he said. “This is another scenic valley, it’s another greenfield coal project. There’s a whole raft of aspects of this decision in Rocky Hill which would seem broadly applicable to the project proposed in the Bylong Valley.”

Morris said other proposals where the case could prove relevant were Whitehaven’s Vickery extension project, Peabody’s Wambo joint venture and the Hume coal project.

Gloucester Resources has 28 days to decide if it will appeal the court’s decision.

The NSW Minerals Council has rejected the suggestion the case will have widespread ramifications.

“We’ll take a close look at the judgment, including what appears to be a range of different reasons for the outcome,” said Stephen Galilee, the council’s chief executive. “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.”

But George Woods, the NSW coordinator of the anti-mining action group Lock the Gate Alliance, said communities would be looking to the Independent Planning Commission for “leadership and direction” in the wake of the court’s decision.

“Bylong is the very next decision the commission will make about a new mine,” she said. “What we’d hope is this judgment would prompt the commission to seek advice that would put the emissions from Bylong in the context of a carbon budget consistent with meeting the Paris agreement.”

Brendan Sydes, the chief executive of Environmental Justice Australia, said the Rocky Hill case was “dramatically different in the sense that every argument that has been successfully put forward by mining companies in the past has been completely considered, discredited and rejected”.

He said that included considering the impact of emissions from coal that was exported and burned elsewhere, as well as the argument that if coal was not dug up and burned from one mine, it would simply happen somewhere else.

“We now have this anomalous situation that the most up-to-date and thoroughgoing analysis of the impact of new coalmines by an Australian court has adopted reasoning in a manner that’s inconsistent with the reasoning that has been adopted to support the approval of the Adani mine,” Sydes said.

Comment was sought from the NSW Independent Planning Commission.