In 1970, Congress enacted the National Environmental Policy Act (NEPA) (42 U.S.C. 4321-4347) with its sweeping national policy to, among other things, encourage harmony between man and his environment, to promote efforts which will prevent or eliminate damage to the environment and biosphere, and to enrich the understanding of the ecological systems and natural resources important to the Nation. Pursuant to this declared policy, the Act imposes the continued responsibility on the federal government to evaluate, improve and coordinate all federal plans, functions, programs and resources to various enumerated ends in order to fulfill the purposes of the law.
NEPA is a process-oriented statute. It requires federal agencies to follow a specific process to evaluate the environmental effects of actions that include some federal component (i.e. actions taken by federal agencies or actions funded in part by federal monies). In addition to evaluating the effects of the proposed action, NEPA requires the development of reasonable alternatives that will avoid or minimize adverse effects of the action on the environment. However, NEPA does not require the federal agency to choose the alternative with the least impact on the environment. It only requires the federal agency to consider the environmental impacts before making a final decision.
Initially, the federal agency develops an Environmental Assessment (EA). If the EA results in a decision that the proposed action will not result in significant impact to the environment, no further analysis is required. If the assessment results in a decision that the proposed action will result in significant impact, the agency must conduct a more thorough analysis, known as an Environmental Impact Statement (EIS). The public may comment on the analysis and the federal agency is required to hold public hearings for public comment on the proposed action and the EIS.
(Always refer to the most current version of the law, either by checking the compiled laws, or referring to the U.S.Code Service site above.)