A mountain climber died of hypothermia in the Grand Teton National Park (park) after straying from a trail, falling, and sustaining a head injury. The climber’s body was found by a helicopter the morning after members of the climbing party requested assistance from a park ranger. The climber’s survivors (survivors) (plaintiffs) sued the United States government (government) (defendant) in district court, claiming that the National Park Service (NPS) was negligent in failing to adequately regulate mountain climbing in the park, and in failing to conduct a search effort immediately after the climbing party’s request for assistance. The survivors also claimed that the discretionary-function exception of the Federal Tort Claims Act (FTCA), 28 U.S.C. §§ 1346(b) and 2671-80, did not apply to NPS decisions regulating mountain climbing, because the decisions did not implicate social, economic, or political-party considerations. No federal statutes or regulations specified how the NPS should regulate mountain climbing, and the NPS did not have a mountain-climbing policy or climbing regulations. The district court granted summary judgment in favor of the government. The survivors appealed. The park superintendent justified the park’s decision not to regulate mountain climbing based on social- and economic-policy reasons that included: (1) the fact that mountain climbing was an inherently dangerous activity, (2) the need to conserve park staff and economic resources for availability during emergency situations, (3) the economic impracticability or impossibility of testing climber competency and of monitoring equipment use, and (4) the fact that park visitors valued mountain climbing as an unregulated experience.