Environment minister Sussan Ley appealed ruling that she had a duty of care to avoid harming children when weighing approval for a coal project.
An Australian court on Tuesday overturned a groundbreaking ruling from last year that required the country's environment minister to consider harm to children from climate change before approving a coal mine.
The full Federal Court decided unanimously in favour of the appeal by Environment Minister Sussan Ley against a judge's ruling that she had a duty of care to avoid harming children when weighing approval for a coal project. The court ruled "the duty should not be imposed upon the Minister".
Australia is the world's second-largest exporter of coal used in power generation, in terms of export volume. It ranked "dead last" for the climate action taken among comparable developed countries since nations pledged in the 2015 Paris agreement to take steps to limit global warming, according to a report from the Climate Council in October.
The original ruling, which related to approval of a coal mine extension in the state of New South Wales, was seen as setting a precedent for other mine applications. Ms Ley approved the mine, run by Whitehaven Coal, last September ahead of the appeal.
Emissions from burning the coal from the mine project were estimated at 100 million tonnes of carbon dioxide-equivalent.
The case was brought by eight schoolchildren and a nun seeking to require Australia's environment minister to protect children from future harm caused by climate change.
Some of the children had gathered outside the court in Sydney to await the ruling and were left in tears when the decision was announced.
"Today's ruling leaves us devastated, but it will not deter us in our fight for climate justice," Anjali Sharma, 17, one of the students who brought the original case, said in a statement.
Chief Justice James Allsop said the duty of care should not be imposed because the minister could not be held liable for "all damage by heatwaves, bushfires and rising sea levels to all Australians under the age of 18, ongoing into the future".
The court also said the duty would not fit with the minister's role set out in the environmental protection law that governs mine approvals.
Anti-coal activists Lock the Gate said the judgement, coming in the wake of historic flooding on the country's east coast, showed Australia's environmental laws are too weak.
Ms Ley welcomed the decision and said the government remained committed to protecting the environment.