Federal agency decisionmaking that affects the environment is influenced by a variety of factors. Among them are the statutes and executive orders that define an agency's mandate; the standards of review applied by the courts; the attitudes of agency personnel; the agency's relationships with groups in the private sector, the congressional committees with jurisdiction over its programs, other federal agencies such as the Office of Management and Budget, and the public; and the priorities and politics of the administration in power.

Because there recently have been significant changes in many of these variables, some background is necessary. Prior to 1970, federal agencies took environmental protection into account very little in carrying out their responsibilities. There were few federal statutes with environmental protection objectives, and they were usually weak and left much to agency discretion. Even agencies with traditional environmental quality concerns, such as the Forest Service, began to place their emphasis on resource development. Among the consequences were the massive coal-fired power plants in the Four Corners area of the Southwest, for which federal permits were granted without thought for orderly development or environmental protection; the Santa Barbara oil spill, which was caused by a failure of the Geological Survey to impose adequate environmental safeguards on the company drilling the well; and the desecration of the beautiful Bitterroot National Forest due to indiscriminate clearcutting.