Santos Ltd.'s $5.8 billion Barossa offshore gas project received a crucial boost on Monday as the Australian Federal Court dismissed a legal challenge by a group of Tiwi Islanders seeking to halt construction of a key pipeline.

Justice Natalie Charlesworth lifted a temporary injunction that had prevented Santos from commencing work in a specific area along the pipeline route, paving the way for the company to push ahead with construction.

The decision follows December's approval of the project's drilling program by the National Offshore Petroleum Safety and Environmental Management Authority (Nopsema). However, the project has faced hurdles before. An earlier drilling permit was overturned due to insufficient consultation with Tiwi traditional owners.

In this latest case, the Islanders, represented by the Environmental Defenders Office (EDO), argued that Santos had not properly assessed submerged cultural heritage along the pipeline route, particularly near Cape Fourcroy on Bathurst Island. They sought an injunction until Santos submitted a new environmental plan for Nopsema's assessment.

However, Justice Charlesworth found the evidence presented by the Islanders, including claims of potential harm to underwater heritage associated with Crocodile Man songlines and the rainbow serpent Ampiji, lacked broad representation among the affected Tiwi community.

Additionally, she dismissed expert reports on potential impacts to underwater archaeological sites, finding the risk to tangible cultural heritage minimal.

Charlesworth also criticized the cultural mapping exercise conducted by an expert witness for the Islanders, deeming it lacking integrity and potentially constructed rather than reflecting genuine Tiwi traditions.

In her argument, she raised concerns about "subtle coaching" by a cultural heritage expert and EDO lawyer during a meeting with Islanders, suggesting efforts to manipulate their testimonies.

"As per the ruling and in accordance with the environment plan in force for the activity, Santos will continue pipe-laying activity for the Barossa gas project," the company stated.

While the Islanders expressed disappointment with the outcome, declaring their commitment to protecting their "sea country," the ruling provided significant momentum for Santos.

However, Alex Hillman, lead analyst at the Australasian Centre for Corporate Responsibility (ACCR), warns that the project's regulatory delays, estimated to have cost Santos around $800 million, raise concerns about shareholder value and optimal project structure.

These concerns, along with the ongoing discussion about consultation regulations for offshore petroleum projects, are likely to remain in the spotlight as the Barossa project moves forward.