Washington State Department of Licensing v. Cougar Den, Inc.

In Washington State Department of Licensing v. Cougar Den, Inc., the U.S. Supreme Court considered whether the State of Washington could tax fuel imported by Cougar Den, a company owned by a Yakama Nation member, over public highways to the reservation. The company argued the 1855 Yakama Treaty, which guarantees the right to travel and transport goods, preempted the state fuel tax. The Washington Supreme Court agreed. In a 5-4 decision authored by Justice Breyer, the U.S. Supreme Court affirmed, holding that the treaty right to transport goods without charge preempts the fuel tax, which functioned as a charge on the exercise of that right. The ruling turned on treaty interpretation and federal preemption principles.

The U.S. Supreme Court affirmed the Washington Supreme Court's ruling in a 5-4 decision, holding that the fuel tax is preempted by the 1855 treaty and cannot be imposed on Cougar Den's fuel imports.

Whether the 1855 Treaty with the Yakama Nation, reserving the right to transport goods over public highways, preempts Washington State's fuel tax as applied to a tribal corporation's importation of fuel.

The decision reinforced tribal treaty rights as supreme over conflicting state laws, strengthening legal protections for tribal sovereignty and commerce. It clarified limits on state taxation authority regarding tribal members and reservation-bound goods, influencing subsequent treaty interpretation and state-tribal fiscal relations.