A federal appeals court ruled Friday that the U.S. Navy was wrongly allowed to use sonar that could harm whales and other marine life. The Ninth U.S. Circuit Court of Appeals reversed a lower court decision upholding approval granted in 2012 for the Navy to use low-frequency sonar for training, testing and routine operations. The five-year approval covered peacetime operations in the Pacific, Atlantic, and Indian Oceans and the Mediterranean Sea. Sonar, used to detect submarines, can injure whales, seals, dolphins and walruses and disrupt their feeding and mating. The 2012 rules adopted by the National Marine Fisheries Service permitted Navy sonar use to affect about 30 whales and two dozen pinnipeds, marine mammals with front and rear flippers such as seals and sea lions, each year. The Navy was required to shut down or delay sonar use if a marine mammal was detected near the ship. Loud sonar pulses also were banned near coastlines and in certain protected waters. Environmental groups, led by the Natural Resources Defense Council, filed a lawsuit in San Francisco in 2012, arguing that the approval violated the Marine Mammal Protection Act. The appellate court ruled 3-0 that the approval rules failed to meet a section of the protection act requiring peacetime oceanic programs to have the least practicable adverse impact on marine mammals." The panel concluded that the fisheries service "did not give adequate protection to ... the world's oceans."