June v. Union Carbide Corporation

Union Carbide and Umetco Minerals (defendants) ran a uranium and vanadium mining operation in Uravan, Colorado, producing 42 million pounds of uranium oxide between 1936 and 1984 before the town was evacuated as an EPA hazardous site. Twenty-seven former Uravan residents (plaintiffs), later diagnosed with cancers or thyroid disease, sued for negligence. The defendants argued the plaintiffs hadn't shown their injuries wouldn't have occurred but for the defendants' conduct. The district court agreed that Colorado law required but-for causation, found the plaintiffs hadn't met that standard, and granted the defendants summary judgment. The plaintiffs appealed, arguing they only needed to show the defendants' radiation emissions were a substantial factor in their injuries.