The U.S. Supreme Court most properly held in Marsh v. Oregon Natural Resources Council that it would be "incongruous" if "blinders to adverse environmental effects, once unequivocally removed, [were] restored prior to the completion of agency action simply because the relevant proposal has received initial approval." Many "actions" taken by federal agencies are not discrete, one-time events, but rather represent "ongoing actions" to which continuing obligations under the National Environmental Policy Act (NEPA) must attach for the Act's purpose to be realized. In addition, the information and circumstances set out may significantly change during the pendency of an ongoing action, such as during implementation of a plan. The pending case of Norton v. Southern Utah Wilderness Alliance provides an opportunity for the Court to reiterate and reinforce its commitment to the application of NEPA to the ongoing actions of the federal government.

In applying NEPA to ongoing actions of federal agencies, at least three of the Act's "action-forcing" devices are potentially applicable--§102(2)(C)'s environmental impact statement (EIS) requirement (with its significance threshold), §102(2)(E)'s environmental assessment (EA) requirement (which has no such threshold), and §102(1)'s requirement for agencies to act in accordance with the policies set out in NEPA (also with no significance threshold).