They were all in court last week for a case that could make or break the future of Australian coal.

The Environment Council of Central Queensland is challenging the Minister's risk assessment of a proposal to expand the life of Narrabri's Maules Creek Coal Mine for nine years, to 2043.

The non-profit was represented in court last week by lawyers from Environmental Justice Australia (EJA), who say the stakes couldn't be higher.

They said a win for their side would compel Minister Plibersek to reconsider 19 recently-approved coal and gas proposals across the country, due to their climate risks.

But a decision in favour of the Minister would set a legal precedent for allowing the Australian Government to ignore climate change when making risk assessments on coal and gas mining.

There are currently more than two dozen new coal and gas projects waiting for ministerial approval, approval Ms Plibersek says she will not give until the court delivers its decision.

One such project is Idemitsu's Boggabri Coal Mine, which recently got the go-ahead from the NSW government to extend operations for six years and is now waiting for a green light from the Minister.

The Environment Minister's legal team argued her assessment of mines in Narrabri and Mount Pleasant applied the law correctly, and said while the Minister agrees coal projects indirectly cause climate harm, she does not believe each individual mine makes a "substantial contribution".

Lawyers for mining companies Whitehaven and MACH Energy also said the Minister's assessment is correct, and that their coal mines are not a 'substantial cause' of climate harm.

The Leader contacted Whitehaven for comment on the case, and the company said it's proud of the "significant contribution" its underground mine has made to the Narrabri community since opening in 2012.

"The Narrabri Stage 3 Extension Project will extend the life of the mine from 2031 to 2044 and support the ongoing delivery of a range of benefits to North West NSW," a Whitehaven spokesperson said.

"The project will provide continued employment for hundreds of locals and allow the social and economic benefits associated with the mine, including spend with local businesses and royalty payments to the NSW Government, to continue for decades to come."

On the other side, lawyers from the EJA said the Minister's assessment used a "drug-dealers' defence" and "drop in the ocean logic" to justify both mines' continued operation.

"Digging up and burning coal is the single biggest cause of climate damage, which is causing vast and irreversible harm to the animals, plants and places we all love. And when we do it, we are likely to cause that harm," the lawyers' office said in a media release.

"This, in simple terms, is part of the logic behind the Living Wonders legal intervention."

The judgement will be delivered at a later date.

Stay tuned.