The court had to determine whether Canada had adequately consulted with Indigenous groups living along the Trans Mountain route.
Canada's Federal Court of Appeal approved Tuesday the Trans Mountain Pipeline expansion project, dismissing four legal challenges from First Nations.
The court had to determine whether Canada had adequately consulted with Indigenous groups living along the Trans Mountain route (1,150km), from Edmonton, Alberta, to a terminal on the British Columbia (BC) coast.
It said the government's consultation process "was anything but a rubber-stamping exercise."
"The evidentiary record shows a genuine effort in ascertaining and taking into account the key concerns of the applicants, considering them, engaging in two-way communication, and considering and sometimes agreeing to accommodations."
"It is true that the applicants are of the view that their concerns have not been fully met, but to insist on that happening is to impose a standard of perfection, a standard not required by law," the court said.
Indigenous groups had raised concerns about the project's consequences on the environment and their rights. They also raised fears that an increase in tanker traffic off the BC coast near Vancouver could lead to a spill.
In December, they told the Federal Court of Appeal they were not adequately consulted by the government between August 2018 and June 2019.
Canada has what is called a "duty to consult" Indigenous groups when their rights may be affected by resource development projects that cut across their territories.
Chief Lee Spahan of the Coldwater Indian Band, a Nlaka'pamux Nation community in the BC interior said that Canada's consultation with his community was "not meaningful at all."
"It wasn't meaningful. Canada had their mindset already on this decision," Spahan said, adding that an appeal to the supreme court is under consideration.
Indigenous leaders, environmental groups and politicians at the federal, provincial and municipal levels have opposed the highly contentious Trans Mountain project.
Prime Minister Justin Trudeau has insisted that the Trans Mountain pipeline is in the best interests of all Canadians. His government welcomed Tuesday the court's decision.
The US$5.6 billion expansion project would see the pipeline's flow of oil nearly tripled.