Idaho v. United States, 533 U.S. 262 (2001), was a United States Supreme Court case in which the Court held that the United States, not the state of Idaho, held title to lands submerged under Lake Coeur d'Alene and the St. Joe River, and that the land was held in trust for the Coeur d'Alene Tribe as part of its reservation, and in recognition of the importance of traditional tribal uses of these areas for basic food and other needs.

Lake Coeur d'Alene, officially Coeur d'Alene Lake, is a natural dam-controlled lake in North Idaho, located in the Pacific Northwest region of the United States. At its northern end is the city of Coeur d'Alene. It spans 25 miles (40 km) in length and ranges from 1 to 3 miles (5 km) wide with over 109 miles (175 km) of shoreline.