In a federal lawsuit over the legality of a new Navy sonar system said to harm marine animals, the Bush administration is challenging the scope of one of the most important pieces of U.S. environmental legislation, the National Environmental Policy Act. The act requires federal agencies to review the environmental implications of their projects, but the Justice Department claims the law should not apply to projects beyond the nation’s territorial waters, which extend just three miles from shore. The Natural Resources Defense Council, which is arguing the other side of the lawsuit, contends that the act applies to the nation’s exclusive economic zone, which extends 200 miles from shore. Environmentalists say the Bush administration’s interpretation would leave the vast majority of waters under U.S. control open to military maneuvers, oil and gas pipelines, commercial fishing, ocean dumping, and other potentially destructive activities — all without environmental review.