“This case sends a signal that governments need to abide by modern treaties they’ve signed,” he said.

The joint commission, which was made up of appointees from the First Nations and the Yukon government, spent seven years negotiating with both sides before presenting a final recommendation in 2011 to set aside 80 percent of the wilderness for conservation, with the rest allotted for road construction and resource extraction. But in 2014, the Yukon government rejected the commission’s plan and adopted its own version, which would have opened more than two-thirds of the area to industrial development.

The First Nations, joined by two environmental groups, filed a lawsuit, arguing that the government had violated its treaty obligations and must accept the commission’s final recommendation. Two lower courts ruled in their favor but disagreed over whether the government could rewind negotiations for a better deal.

In its decision, the Supreme Court ruled that the Yukon government had acted in bad faith, and can only approve, reject or modify the commission’s final recommendation after further consultations with indigenous groups.

“Yukon’s changes to the Final Recommended Plan did not respect the land use planning process in the Final Agreements and its conduct was not becoming of the honor of the Crown,” the court said, referring to the Canadian government.