Here is the opinion in Muckleshoot Indian Tribe v. Tulalip Tribes, subproceeding 17-02 of United States v. Washington.
Lower court materials here.
Here is the opinion. And the briefs:
Here are the intervening tribes and organizations:
Bay Mills Indian Community, Grand Traverse Band of Ottawa and Chippewa Indians, Jamestown S’Klallam Tribe, Lac Courte Oreilles Band of Lake Superior Chippewa Indians, Little River Band of Ottawa Indians, Little Traverse Bay Bands of Odawa Indians, Lower Elwha Klallam Tribe, Lummi Nation, Minnesota Chippewa Tribe, National Congress of American Indians, Nisqually Tribe, and Swinomish Indian Tribe Community
Here, starting on page 19.