On Tuesday, Court of Appeal Justice David Harris dismissed an action by James Robinson and Mercy Thomas, ruling the legislative and self-government powers granted to the nation by the Nisga'a Final Agreement are constitutionally valid.
Robinson and Thomas argued the treaty is an attempt to create a "third order of government."
They also argued the treaty was an abdication of federal and provincial powers, noting it gives the nation the power to tax and create courts of law.
"The treaty has been carefully crafted to respect constitutional principle and to fit into the wider constitutional fabric of Canada," Harris said in his written ruling.
"It is what it purports to be: an honourable attempt to resolve important but disputed claims, to achieve reconciliation and to lay the foundation for productive and harmonious future relationship between the Nisga'a Nation and the non-Aboriginal population of Canada."
The treaty came into force on May 11, 2000, almost two years after the Nisga'a and the governments of Canada and B.C. concluded negotiations.
It granted the nation financial compensation and fee-simple land, defined hunting, fishing and trapping rights beyond that land, and established a Nisga'a government with specific legislative powers.
The treaty is not supposed to alter the constitution or the division of powers between the federal government and British Columbia.
The case marks the second time the treaty has been upheld. An earlier court challenge was dismissed in 2000.