Whether, under NEPA, an agency that carefully considers all criticisms of its environmental analysis must also 'resolve' those criticisms to the court's satisfaction to justify a finding of no significant impact

QUESTIONS PRESENTED The National Environmental Policy Act (“NEPA”) requires that, before taking any “major Federal action[] significantly affecting the quality of the human environment,” a federal agency must first prepare a “detailed” environmental impact statement (“EIS”). 42 U.S.C. § 4332(2)(C). The agency first prepares a shorter environmental assessment to determine whether the action’s environmental impacts are “significant.” If so, the agency prepares an EIS; if not, it prepares a finding of no significant impact. In Marsh v. Oregon Natural Resources Council, this Court held that when reviewing an agency’s decision to forgo an EIS, courts must “defer” to the agency’s “informed discretion” even when they “find contrary views more persuasive.” 490 U.S. 360, 37778 (1989). In the decision below, however, the D.C. Circuit deviated from that approach. It asked whether the U.S. Army Corps of Engineers had “convinced the court” it was unnecessary to prepare an EIS—on top of the hundreds of pages of environmental analysis the Corps already performed—for the Corps’ decision to grant an easement for a pipeline that crosses a narrow strip of federally owned land. App. 15a-16a. Because the panel was not convinced by the Corps’ response to criticisms of the pipeline, it upheld the district court’s orders requiring the Corps to prepare an EIS and vacating the easement. The questions presented are: 1. Whether, under NEPA, an agency that carefully considers all criticisms of its environmental analysis must also “resolve” those criticisms to the court’s satisfaction to justify a finding of no significant impact; and ii 2. Whether procedural error under NEPA per se warrants remand with vacatur.