Marsh v. Oregon Natural Resources Council 490 U.S. 360 (1989) The US Army Corps of Engineers was building three dams on a river in Oregon. Pursuant to the National Environmental Protection Act (NEPA), the Corps prepared an Environmental Impact Statement (EIS). After the final EIS had been completed, new studied were published indicating that the projected would have a more adverse impact than previously thought. The Corps decided not to prepare a supplemental EIS to consider this new information. NEPA does not explicitly address what to do in this situation. The Council on Environmental Quality (CEQ) had interpreted NEPA to require a supplemental EIS when there is "significant new circumstances or information relevant to environmental concerns and bearing on the proposed action or its impacts." The Corps own regulations require a supplemental EIS when there is "new significant impact information, criteria, or circumstances relevant to environmental considerations impacting on the recommended plan or proposed action." Marsh sued to stop the project on the grounds that the EIS was not adequate. Marsh argued that since new information had come to light, the original EIS was flawed and needed to be updated. The Trial Court found for the Corps.  Marsh appealed. The Appellate Court reversed and issued an injunction.  The Corps appealed. The Appellate Court found that the Corps had failed to evaluate the new information with sufficient care and therefore had failed to meet the requirements of NEPA. The US Supreme Court reversed the Appellate Court and allowed the project to go forward without the need for a supplemental EIS. The US Supreme Court found that the decision to prepare a supplemental EIS is similar to the decision to prepare an EIS in the first place. The Court found that judicial review of agency decisions is limited to whether they were 'arbitrary or capricious'. Basically, the Court was saying that whether the new information was 'significant' was a scientific fact that was beyond the scope of a court to review.  Deference should be given to the scientists in the agency to decide what constitutes a significant change.