The Wilderness Society says it hopes a Supreme Court challenge will result in a review of the environmental approvals of the Kimberley gas hub.
The first hearing is scheduled for this morning in Perth.
Society spokesman Peter Robertson says the court action was filed after the EPA's chairman made the sole decision to approve the gas hub because all other board members had a perceived conflict of interest.
"The outcome that we're hoping for is that the Supreme Court will agree with us that the way that the EPA handled this fiasco was unlawful," he said.
"And, therefore any so-called approvals that arise from is should be overturned - that's what we're seeking."