The Capoemans (plaintiffs) were members of the Quinaielt Tribe of Indians (the tribe) and lived on the tribe’s reservation in Washington. The reservation was established by treaty (the treaty) between 1855 and 1856, which gave the tribe exclusive use of the land. In 1887 Congress passed an act under which members of the tribe were allotted plots of land on the reservation, which were to be held in trust by the US government and eventually transferred to the tribe members as fee-patent land free of all charges and encumbrances. The act did not specifically reference taxes. Pursuant to the treaty and the act, the tribe members were allotted land in 1907. In 1943, while the government still held title to the Capoemans’ allotted land in trust, the government sold the timber on the land, which accounted for most of the value of the land, and received money in exchange on the Capoemans’ behalf. The Collector of Internal Revenue (defendant) required the Capoemans to report and pay taxes on the proceeds from the timber sale. The Capoemans filed for a refund, claiming the proceeds were not subject to income tax and that collection of income tax violated the treaty and the act. After the Capoemans’ claim for a refund was denied, they filed suit in a federal district court. The district court agreed with the Capoemans and ordered a refund. The court of appeals affirmed but recognized a conflict between its decision and a decision in another federal court of appeals. The United States Supreme Court granted certiorari to resolve the conflict.