The Makah Indian Tribe (Makah) (defendant) had a tradition of hunting California gray whales that migrated annually through a federal marine sanctuary. The Makah ceased whaling in the 1920s, as commercial whaling had nearly extinguished the gray-whale population. In 1946, the United States signed a treaty that regulated whaling through the International Whaling Commission (IWC). The IWC banned the taking or killing of gray whales. The National Oceanic and Atmospheric Administration (NOAA) (defendant) and the National Marine Fisheries Service (NMFS) (defendant) were responsible for implementing the treaty obligations. By 1993, the gray-whale population had recovered, and the Makah decided to resume hunting gray whales. The Makah asked NOAA and NMFS to request the IWC’s approval for an annual quota of up to five whales. NMFS represented the Makah at IWC meetings in 1995 and 1996, and also entered into a written agreement with the Makah in 1996 to make a formal quota proposal to the IWC and to participate in whaling management. In August 1997, NOAA prepared a draft environmental assessment (EA) on the proposed whaling, in accordance with the National Environmental Policy Act (NEPA). On October 13, 1997, NOAA and the Makah signed a new whaling agreement. On October 17, 1997, NOAA issued a final EA and a Finding of No Significant Impact (FONSI). NOAA authorized the Makah’s whaling in 1998. Jack Metcalf and others (plaintiffs) sued the Makah and the heads of NOAA and NMFS (defendants) in district court, claiming that the federal government had violated NEPA by preparing the EA only after signing two agreements with the Makah. The district court granted the defendants’ motion for summary judgment, and the plaintiffs appealed.