The Australian Conservation Foundation has failed to block Indian conglomerate Adani’s Carmichael planned coal mine project in Queensland's Galilee basin.
The Federal Court today dismissed the ACF's case, which argued the mammoth mine undermined Australia's responsibility to protect the Great Barrier Reef, a world heritage site.
This year the reef has endured unprecedented coral bleaching, with climate scientists warning coal emissions are a major contributing factor to rising sea temperatures.
"We had a strong case but the laws in Australia are simply too weak to protect places like the Great Barrier Reef against coal pollution," the ACF's chief executive Kelly O'Shanassy told BuzzFeed News.
"When it comes to climate change, the environment laws in Australia don't really account for it."
The Carmichael mine would produce 128.4 million tonnes of carbon pollution per year at peak production - four times the annual carbon emissions of New Zealand - and affect an area of 27,892 hectares, the ACF has argued.
"We will do everything we can to stop this coal mine going ahead," O'Shanassy said.
"If there is an opportunity for appeal, we won't rule that out."
The Queensland government has defended granting mining leases for the project, which it claims will create thousands of jobs and inject hundreds of millions of dollars into the state's coffers annually.
Earlier this month the Federal Court dismissed another challenge, from Indigenous traditional owner Adrian Burragubba, who argued the approval of mining leases would extinguish native title over the parts of the Wangan and Jagalingou people's land.