Woodside's massive Scarborough gas development is facing yet another legal challenge, with activists again targeting the project's environmental approvals.
The Conservation Council of Western Australia is challenging a decision by WA's Department of Water and Environmental Regulation to approve construction of Woodside's second Pluto LNG train.
It claims the decision is unlawful because pollution and environmental harm from greenhouse gas emissions was not properly considered.
A two-day hearing is expected to begin on Tuesday in the WA Supreme Court.
An appendix to the department's decision, issued in May last year, states that greenhouse gas emissions from the project were regulated by WA's Environmental Protection Authority and had "therefore not been considered in this assessment".
Under departmental guidelines, conditions should not be set which created unnecessary duplication, the document said.
The conservation council said the expansion of the Pluto facility, a key component of the $16 billion Scarborough project, would nearly double its emissions once the site was fully operational.
"We firmly believe that governments and their departments have a legal and moral duty to use all their available powers to prevent damage to our climate," executive director Maggie Wood said.
"In this case, we argue that the state government, by failing to properly consider the environmental harm of this highly polluting proposal, has failed in that duty."
A report by the WA conservation council and the Australia Institute last year claimed the Scarborough project would release 1.6 billion tonnes of greenhouse gases in its lifetime, or the equivalent of 15 coal-fired power plants.
But Woodside disputes that, saying total scope one and three emissions will be significantly less.
"Woodside has complied with regulatory requirements and environmental processes in seeking and receiving its approvals," a spokesperson said.
"Woodside will vigorously defend its position."
A judge earlier this year rejected a separate conservation council challenge against approvals granted for Scarborough by WA's environment watchdog.
The Australian Conservation Foundation last month filed its own action in the Federal Court, seeking to halt the project until its impact on the Great Barrier Reef is assessed under environmental laws.
The Scarborough field, about 375km off the WA coast, is estimated to contain 11.1 trillion cubic feet of gas that will be transported via a 430km pipeline to the Pluto LNG plant.
Much of the gas will be exported, but some will supply domestic markets.