But the Federal Court decision is being hailed by a Tasmanian researcher as a step in the right direction for the climate, sitting alongside a suite of recent legal cases fighting for preventative environmental action.

The recent negligence case found that federal Environment Minister Sussan Ley had a duty of care to avoid causing harm or injury to children, and that she should consider this duty when deciding whether to grant approval for a coal mine extension under the Environment Protection and Biodiversity Conservation Act.

University of Tasmania torts lecturer Jane Nielsen said the decision would almost certainly be appealed.

"The judge thought it was a mandatory consideration ... that [the Minister] is compelled to think about the health of the children of Australia when making decisions that might impact the environment. That is a very broad reaching idea and on that basis alone they are likely to appeal," Associate Professor Nielsen said.

"It is unusual for a court to impose such a broad duty of care, particularly on a statutory government authority, and basically to a class of people that is pretty indeterminate.

"This idea that you could owe a duty of care to all children of Australia, including future children? It is just such a vast class."

The case, according to University of Tasmania climate change communication researcher Gabi Mocatta, is part of a growing trend towards positive climate decision making.

Dr Mocatta said such cases begin to create a legal framework that would make it more difficult for companies to pollute with carbon dioxide.

She said they also send a strong message to policy makers to act against climate change which, when combined with a public groundswell for action, might actually start to instigate change.

"This decision came a week after the Australian Conservation Foundation won their challenge against the Adani pipeline. It also came in the same month that a Dutch court ordered Shell to cut its carbon dioxide emissions by 45 per cent by 2030," Dr Mocatta said.

"We would hope and expect that these types of climate decisions are going to start happening more and more ... these are really significant legal decisions, and it is really good news for climate."

Associate Professor Nielsen agreed that more cases like this one could occur in the future.

"I can absolutely see that more of these cases will eventuate but decisions like this have to be well grounded and judges have to be really careful that their position is defensible."

In his judgement Justice Mordecai Bromberg held that the applicant had established a novel duty of care in the law of negligence, but did not grant an injunction to stop the coalmine extension as submissions to the court had not established a breach of that duty.

"By reference to contemporary social conditions and community standards, a reasonable Minister for the Environment ought to have the Children in contemplation when facilitating the emission of 100 Mt of CO2 into the Earth's atmosphere," he wrote in the judgement.

"She [Minister Ley] will now appreciate, contrary to the submissions made on her behalf at the trial, that in deciding whether or not to approve the extension project she must take into account, as a mandatory relevant consideration, the avoidance of personal injury to people.

"She now knows that a duty of care owed by her to the Children has been demonstrated and that ... it will now be recognised by law."