The National Environmental Policy Act of 1969, Pub. L. No. 91-190, was signed into law by President Nixon January 1, 1970. It was thought at the time to constitute both an “environmental charter” for the Nation as well as a signal achievement in legislative politics. It introduced several innovative tools to our public law, chief among them the “impact statement.” Since 1970, NEPA has become the most widely emulated, litigated, and studied (and arguably the most misunderstood) environmental statute in the US.
In its “procedural” aspects NEPA requires every federal “agency” to examine its major discretionary decisions and decide whether they will (or may) significantly affect the quality of the human environment. If the answer is “yes,” that agency must first prepare an “environmental impact statement.” Agencies have implemented this duty to include a variety of other deliverables, including “environmental assessments” (a preliminary determination of probable “significance” where the matter is in doubt), findings of no significant impact (where the foregoing determination is negative), and records of decision (what it sounds like). Each of these deliverables is reviewable in federal court as final agency action.
As codified, NEPA’s text can be found here.