The Oneida Indians (plaintiffs) lost most of Oneida land through treaties with the United States. As of the mid-1700s, the Oneida Indians lived on a 300,000-acre reservation in central New York. In 1790, the United States passed the Indian Trade and Intercourse Act (ITIA), 1 Stat. 137, which prohibited the sale of Indian land unless the sale was governed by treaty. However, in 1795, the State of New York purchased the remainder of Oneida land from the Oneida Indians in exchange for cash payments. In 1970, the Oneida Indians sued the Counties of Oneida and Madison, New York (Counties) (defendants), alleging that the county purchase of land from the Oneida Indians in 1795 violated the ITIA and was void. The Oneida Indians sought to recover as damages the fair market value of the land. The district court held that the 1795 sale violated ITIA. The United States Court of Appeals for the Second Circuit affirmed. The United States Supreme Court granted the Counties' petition for certiorari. The Counties argued before the Supreme Court that the Oneida Indians had no right to bring a federal common-law claim for violations of ITIA.