The band filed an application with the court on Monday, bringing to at least five the number of groups seeking judicial review of the federal cabinet's decision approving the project.
"The Gitga'at put forward evidence of title to specific areas in the Douglas Channel," said their lawyer, Michael Lee Ross.
Last month, the Supreme Court of Canada recognized the Tsilhqot'in nations' aboriginal title to more than 1,700 square kilometres of land in the B.C. Interior. Theirs was the first such recognition in the country.
Ross said the Gitga'at's participation in the joint review process provided a legal basis for declaring the North Coast community's title over their traditional marine territory.
Such a declaration would mean the band would have to approve of the project, or the federal government would have to prove it was in the national interest, he said.
The pipeline and tankers present little or no economic benefit to the community and do not meet the criteria set out by the high court for infringing on their territory, Ross argued.
He said they do present significant threats to Hartley Bay, the village best known for rescuing passengers from the sunken Queen of the North ferry.
"Gitga'at did try to engage with the federal government in a more serious way about some of these things and they really didn't get anywhere," Lee said.
"It's not like they just immediately said, 'well, we're going to go after title.'"
Two other legal challenges were also filed on Monday, the 15-day deadline set out in new rules brought in by the Conservative government.
The Heiltsuk and the Kitasoo-Xaixais added their names to a list of groups that want the Federal Court of Appeal to review the cabinet decision.
Those First Nations, whose territory on the central coast is also along the tanker path of the project, say they will fight the pipeline in court "and, if necessary, on the land."
"Our people have been clear since this pipeline was proposed," said Heiltsuk Chief Councillor Marilyn Slett.
"We will not allow this to threaten our waters. We stand with our relatives up and down the coast in rejecting this frightful project."
The environmental group B.C. Nature also filed an application with the court, bringing to at least five the number of legal challenges filed in the past few days.
All claim the federal cabinet's decision last month is invalid because it's based on a flawed report from a joint review panel.
B.C. Nature's lawyer, Chris Tollefson of the Environmental Law Centre at the University of Victoria, said cabinet was also legally required to give its reasons for approving the pipeline, which it did not.
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