Papua New Guinea landowners who sued Rio Tinto Group over claims of human-rights abuses must show that they aren’t required to exhaust legal options at home before pursuing the U.S. case, an appeals court said. The court in San Francisco…ordered a district court judge to decide whether an “exhaustion requirement” should be imposed on the plaintiffs…. The landowners claim a former copper mine on Bougainville Island contributed to the deaths of thousands of people and damaged the environment.