The Idaho case was a dispute between the United States and the State of Idaho over the ownership of certain lands in the state. The United States claimed that the lands were part of the public domain and that the state had no right to them. The Supreme Court held that the United States had a valid claim to the lands, and that the state had no right to them. The Court reasoned that the United States had acquired the lands through the Treaty of Guadalupe Hidalgo, which was a treaty between the United States and Mexico that ended the Mexican-American War. The Court also held that the United States had a valid claim to the lands because it had acquired them through the Homestead Act of 1862, which allowed settlers to acquire public lands for free. The Court concluded that the United States had a valid claim to the lands and that the state had no right to them.

In the case of The Idaho, Chief Justice Waite delivered a dissenting opinion. He argued that Congress had no authority to pass an act which would grant land to individuals in exchange for their services as soldiers during the Civil War. According to Waite, this was a matter of contract law and should have been left up to the states or private parties. Furthermore, he believed that such an act violated both state sovereignty and property rights by allowing federal interference with contracts between citizens and states without due process of law. In conclusion, Waite argued that Congress did not possess any power under Article I Section 8 Clause 17 (the Property Clause) which allowed it to pass legislation granting lands in exchange for military service; thus making the Act unconstitutional.