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Spring 2023: Comparative and Global Perspectives

NEPA’s Conquest of the World

Tseming Yang


  • Discusses the environmental impact assessment (EIA) as one of America’s most successful exports.
  • Explores how EIAs have been accepted as an international norm in the decades following NEPA’s adoption in the U.S.
  • Looks at the ways in which NEPA has been successful as well as the ways in which it has been criticized.
NEPA’s Conquest of the World
Catherine Falls via Getty Images

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Since the National Environmental Policy Act’s (NEPA’s) adoption in 1969, environmental impact assessment (EIA) has become one of America’s most successful legal exports. Its embedded legal norm—that an EIA must be performed when a project or activity is likely to have a significant environmental impact—has spread to places far from U.S. shores and all across the international system, especially into many international organizations. It has also spawned an entire consulting industry and professional field represented by associations, such as the International Association of Impact Assessment (IAIA), with membership numbering in the thousands.

However, only in the last couple of decades has NEPA’s conquest of the world become complete. In 2010, the International Court of Justice (ICJ) pronounced the EIA norm as binding customary international law in the transboundary context. A recent 197-jurisdiction survey of EIA legislation shows that the EIA norm is now embedded within the environmental laws of developed and developing countries alike. Tseming Yang, The Emergence of the Environmental Impact Assessment Duty as a Global Legal Norm and General Principle of Law, 70 Hastings L.J. 525 (2019) [hereinafter Yang]. These developments and their implications are explored in this article.

NEPA at the Dawn of Modern Environmental Law

The enactment of the National Environmental Policy Act of 1969 (NEPA), 42 U.S.C. §§ 4331–4370, not only ushered in the era of modern environmental law, but also introduced the EIA norm to the world. Its source is a short legislative provision requiring preparation of a “detailed statement . . . on the environmental impact” of any proposed major federal action. 42 U.S.C. § 4331(C). It is not clear whether Congress was fully aware that it was creating the EIA through the “detailed statement” requirement. Some have described it as the product of legislative fortuity and as an afterthought, arising from Senate hearing testimony of Professor Lynton Caldwell of Indiana University.

Since then, this simple requirement has spawned a complex process elaborated by agency regulations and litigated in a plethora of cases. In its essence, NEPA’s EIA norm is a requirement to stop and consider environmental consequences before acting, a process that requires investigation and evaluation of the environmental effects before a project, development proposal, or other government action may go forward. The process then generates a document analyzing the environmental consequences, including biophysical, social, and other relevant concerns, and alternative courses of actions, the “environmental impact statement” or “environmental assessment” under NEPA. The document is made available to the public for review and is considered by the government agency before deciding whether and how to proceed.

Even in its early days, NEPA was both celebrated and maligned. Some described it as fundamentally altering environmental planning, while others accused it of doing little to stem the tide of environmental destruction brought on by the modern world. In spite of its flaws, environmentalists, planners, and regulators have universally come to accept it as a critical and fundamental component of modern environmental regulatory systems. The EIA norm has helped establish the crucial role of the public and its legitimate concerns in environmental regulation. NEPA has also helped institutionalize the expectation that officials across the world should pause and consider the potential impacts of a proposed government action before proceeding. In addition, it has opened up governmental decision-making processes to the scrutiny of the media, the public, and reviewing courts. A hidden positive effect may well have been to deter the most poorly planned and most environmentally destructive projects that would otherwise have gone forward.

The March of Conquest

Over the five decades since NEPA’s enactment, the basic EIA requirement has spread around the world, becoming both embedded in various forms in public international law as well as codified in the national laws of almost all countries. It was adopted in the national environmental law systems of France in 1977, China in 1979, Brazil in 1981, India in 1986, Mexico in 1988, and the Russian Federation in 1995. Yang, supra, at 532. Even politically isolated states such as North Korea and Cuba have enacted EIA laws. Id. at 545. Within the European Union, Directive 2011/92/EU requires an EIA for public and private projects and Directive 2001/42/EC requires an EIA for plans and programmes for its member countries.

Since NEPA’s enactment, the basic EIA requirement has spread around the world, becoming both embedded in various forms in public international law as well as codified in the national laws of almost all countries.

EIA processes had been adopted in highly visible international instruments and legislation. The 1992 Rio Declaration on Environment and Development called on nations to utilize EIA “as a national instrument . . . for proposed activities that are likely to have a significant adverse impact on the environment.” 1992 Rio Declaration on Environment and Development, Principle 17, June 14, 1992, 31 I.L.M. 874. In 1991, EIA became the focus of the Espoo Convention on Environmental Impact Assessment in a Transboundary Context. It appears as article 206 in the UN Convention on the Law of the Sea and as article 14 of the Convention on Biological Diversity. Its requirements have been incorporated into the Operational Policies and Procedures of the World Bank and other multilateral development banks, which apply to all of the projects that these institutions support financially throughout the world.

The EIA duty has even been raised in international arbitration, such as the 1995 Nuclear Tests case before the ICJ. In 2010, the ICJ declared in the Pulp Mills on the River Uruguay (Argentina v. Uruguay) case that EIA in the transboundary context had become a binding norm of international law. Judgment, 2010 I.C.J. Rep. 14, ¶ 204 (Apr. 20, 2010).

However, these anecdotes do not tell the full story of NEPA’s conquest. In 1992, a survey of EIA legislation around the world by Professor Nick Robinson found only 39 nations with EIA requirements, in addition to a number of treaties and organizations with EIA provisions. Nicholas A. Robinson, International Trends in Environmental Impact Assessment, 19 B.C. Env’t Aff. L. Rev. 591, 595 (1992) [hereinafter Robinson]. Subsequent surveys such as a 1995 report by United Nations Environment Programme (UNEP) and a 1996 study by the IAIA found a growing number of nations adopting an EIA duty. A 1998 study by the International Institute for Environment and Development of then-existing EIA regulations and guidelines provided the most comprehensive survey at that time, counting 108 nations with legislation imposing an EIA duty, a little more than half of all UN member states. Annie Donnelly et al., A Directory of Impact Assessment Guidelines (2d ed. 1998). Some two decades later, a 2018 survey shows that the EIA norm has now been adopted in at least 183 countries and jurisdictions, including the European Union, Palestine, and Taiwan. Yang, supra, at 545.

The Contours of Environmental Impact Assessment Across the World

The 2018 survey results show that at least 183 countries (out of 197), about 93%, impose an EIA duty by legislation and/or regulation and another eight multilateral development banks and national development aid agencies require it as part of their operational processes, including lending practices. The survey also identified six states that did not possess an EIA requirement (Eritrea, Nauru , Singapore, Somalia, South Sudan, and Suriname), while it was unable to ascertain with sufficient confidence the status of eight other states (Barbados, Central African Republic, Holy See, Monaco, San Marino, St. Kitts and Nevis, St. Lucia, and St. Vincent and Grenadines).

There are important variations among the EIA approaches around the world. Nevertheless, it is possible to identify commonly encountered issues, shared approaches, and diverging trends. For example, questions of what an EIA should consist of, how environmentalists and others can be involved, the public availability of EIA documentation, and the substantive effect of the EIA conclusions (i.e., are they merely advisory or does a negative environmental impact require changes to a project proposal) are common issues. Some of these have given rise to shared insights. For example, the significance of a project’s impacts is context dependent and cannot be based solely on the absolute size of a project “without also taking [its] nature and location into consideration,” especially factors such as fauna, flora, soil, water, climate, cultural heritage, and the risk of substantial or irreversible change. Commission v. Ireland, C-392/96 (Sept. 21, 1999), [1999] ECR I-5901 [EU], paras. 65–67.

Other issues are concerns about the adequate analysis of available and reasonable alternative options, improper segmentation or scoping of projects so as to avoid triggering significant impacts, and the requirement to include cumulative impacts in the analysis. A full-blown EIA analysis can be avoided through mitigation measures that abate significant environmental impacts, denoted as a mitigated FONSI (finding of no significant impact) under NEPA. Finally, many jurisdictions, such as Liberia and Kenya, explicitly incorporate EIA into the licensing process, conditioning the grant of a license on an EIA determination that there is no significant impact.

There are also jurisdictions that extend significant deference to the judgment of government agencies with respect to official decisions when examining the adequacy of EIA documents. However, there is also a willingness to order the EIA process to be conducted or completed even after projects have been approved and construction has commenced. Some cases highlight that public participation in the EIA process enjoys significant support, even when government bureaucracies do not always facilitate it. Other judicial opinions show significant variability in approaches to standing (locus standi) to challenge EIA processes. Some jurisdictions, such as Japan, appear to be restrictive on standing, while many other jurisdictions have more liberal standing requirements. Yang, supra, at 545–49.

The newest aspect of EIA processes that is spreading around the world is strategic environmental assessment (SEA), such as embodied in EU Directive 2001/42/EC. While the dominant approach globally is to apply EIA primarily to physical projects and specific government actions, SEA applies the EIA process to broad government programs and plans. SEA in this respect resembles NEPA’s “programmatic” impact assessments. For example, the EU approach describes SEA as “an environmental assessment . . . of certain plans and programmes which are likely to have significant effects on the environment.” Directive 2001/42/EC, art. 1.

Finally, the EIA norm has seen adoption in many international institutions, especially multilateral development banks (MDBs). In 1989, the World Bank began applying EIA requirements to projects that it supported through its lending practices. Yang, supra, at 562–63. Violations of the EIA operational directive and policy can be the subject of the Bank’s Inspection Panel investigations. Thus, MDB EIA requirements extend the applicability of the EIA duty into states that do not have EIA requirements or may not enforce them properly.

Why NEPA’s Success?

NEPA’s conquest is the product of many different factors. A few stand out. First, NEPA’s EIA norm has proven a valuable tool for advancing effective environmental governance. EIA processes enhance the rationality of environmental decision-making by ensuring the availability of key environmental information. EIA also sensitizes officials to environmental concerns by explicitly inserting them into the decision process and helping to internalize concern for environmental quality.

EIA processes also enhance transparency since the gathered information must be disclosed to the public. In turn, that allows environmental organizations to participate more effectively in decision-making processes and promotes accountability of government officials. In the long term, transparency advances environmental sustainability and strengthens democratic governance and the rule of law. Even when transparency has not made national governments more accountable to their own people, it can enhance accountability to the international community. Oftentimes, international organizations, development agencies, and international environmental nongovernmental organizations (NGOs) can use their influence and resources to improve environmental outcomes—for example, by leveraging delayed disbursement or cancellation of aid money, by influential governments applying diplomatic pressure, and by swaying the sympathy and market power of foreign consumers.

The newest aspect of EIA processes that is spreading around the world is strategic environmental assessment (SEA), such as embodied in EU Directive 2001/42/EC.

Another set of reasons relates to globalization. As Professor Robert Percival and I have previously argued, globalization has fueled what we referred to as the emergence of “global environmental law”—environmental law norms that are universally recognized and accepted across jurisdictions. Tseming Yang & Robert V. Percival, The Emergence of Global Environmental Law, 36 Ecology L.Q. 615 (2009). They appear not only in national and local environmental law and governance systems but also in regional and global systems, including multilateral environmental agreements and international organizations. Environmental governance capacity-building and law reform programs supported by the development aid arms of governments and international organizations as well as NGOs and universities have been largely responsible for the adoption of EIA process in many developing countries and emerging economies. Such efforts of transplantation of environmental law are usually associated with efforts by nations to modernize their systems of law and environmental regulatory systems. They may also be driven by environmental treaties that call on member states to adopt EIA process as part of their treaty commitments.

Criticisms of the EIA Norm

EIA processes are clearly not perfect. In fact, those who see the EIA norm as insufficient to protect the environment have not spared their serious misgivings. Professor Joseph Sax, who eventually became a NEPA supporter, wrote in the early days that for improving the administrative process through disclosure requirements, EIA could not be “a more dubious example of wishful thinking,” with little prospect of “significant self-reform by agencies.” Joseph L. Sax, The (Unhappy) Truth About NEPA, 26 Okla. L. Rev. 239, 239, 245 (1973). Instead, he said, NEPA would “produce little except fodder for law review writers and contracts for that newest of growth industries, environmental consulting.” Id. He was certainly correct with respect to the emergence of an entire environmental consulting industry associated with the EIA duty.

Even as EIA has spread around the globe, criticism has not gone away. Developers usually argue that the EIA process is used by environmentalists as a delay tactic and to increase project costs. Internationally, EIA requirements have been maligned as “anti-development, expensive,” and, in the development assistance context, potentially infringing on an aid recipient’s sovereignty or complicating “the administration of aid.” Robinson, supra, at 595. Environmentalist critiques typically focus on effectiveness issues, pointing out that “NEPA’s lack of substantive requirements makes the act little more than a procedural hoop through which federal agencies must jump.” Mark W. Anderson, National Environmental Policy Act, in Berkshire Encyclopedia of Sustainability: The Law and Politics of Sustainability 393, 393 (2010). They argue that EIA is pointless since “[n]othing in [NEPA] itself prohibits actions with adverse environmental impacts as long as they have been identified and considered when making the decision.” Id. at 394.

Internationally, EIA requirements have been maligned as “antidevelopment, expensive,” and, in the development assistance context, potentially infringing on an aid recipient’s sovereignty.

Its lack of a substantive requirement also forms the basis of the second set of criticisms: Insufficient integration with the substantive decision-making process allows the EIA’s process objective to be too readily subverted. In such accounts, government agencies tend to engage in defensive preparation of environmental impact statements to avoid litigation because of their perception that NEPA requirements are used as a harassment tool. Rather than engaging in a real look at the environmental impacts, critics contend that the EIA process is just a paperwork exercise. Yang, supra, at 535–37.

A third issue is the technical complexities of the EIA reports. Their complexity oftentimes makes them inaccessible to the public even though public participation is deemed to be an integral part of the process.

A final concern, dependence on a strong rule of law for its effectiveness, has been less explored. For the EIA process to promote transparency and accountability, mechanisms must be in place to correct failures of the process. A strong legal and regulatory system that assures access to justice is a prerequisite for EIA effectiveness. Yet, such tools and institutions are often weak or nonexistent in nations that do not have a robust rule of law and legal institutions, especially in many developing countries.

Undoubtedly, EIA processes are far from perfect. By themselves, EIA mechanisms are insufficient to constitute a comprehensive environmental protection system. However, they do provide decision-makers with valuable information, insert environmental values into governance, and have had substantively improved environmental outcomes. With respect to most developing countries, such criticisms fail to acknowledge that the alternative to existing EIA processes is not a better process or more effective regulatory mechanism, but no EIA requirement at all. If the alternative is to have no regulatory mechanisms to address pollution, it seems that an EIA system is a win for the environment.


There are at least a few important implications of the global spread of NEPA and its EIA norm. In addition to illustrating EIA as a useful governance tool, it suggests transferability of EIA knowledge across jurisdictions. Familiarity with EIA processes in one system provides important reference points for EIA processes in other systems.

Further, the global adoption of the EIA norm suggests that the norm has become a General Principle of Law or a customary norm of international law—two binding forms of international law independent from international treaties. Customary international law is the set of “general and consistent practice[s] of states followed by them from a sense of legal obligation.” Restatement (Third) Foreign Relations Law of the United States § 102(2) (Am. L. Inst. 1987). There are only a handful of customary norms pertaining to the environment, such as the norm prohibiting transboundary harm, first elaborated in the Trail Smelter case. Trail Smelter Case (U.S. v. Can.), 3 R.I.A.A. 1905 (1938). Separate from customary law, General Principles constitute the principles of law “common to the major legal systems” of the world. Restatement (Third) Foreign Relations Law § 102(3). Examples include estoppel, res judicata, and judicial equality of parties. In the environmental area, there are none as to which there is widespread recognition internationally. Yang, supra, at 551.

Because of the paucity of environmental norms, these two sources of public international law have largely remained of little significance for international environmental law. However, as a global legal principle, the EIA norm has established itself as part of public international law. For international tribunals that look to applicable international law for their adjudications, such as in the International Court of Justice (ICJ), the World Trade Organization (WTO) Dispute Settlement Process, and International Tribunal for the Law of the Sea (ITLOS), the EIA norm would be part of the relevant legal norms.

Of course, the ICJ’s Pulp Mills on the River Uruguay opinion already pronounced the EIA norm in the transboundary context to be part of customary international law. However, the widespread acceptance of the EIA duty as a general principle of law would affirm and extend the norm’s applicability to non-transboundary contexts such as the global commons and any other situations where public international law applies. For example, fishing or whaling activities on the high seas and waste disposal activities at Antarctic research stations could trigger the EIA norm.

The EIA norm would also be applicable in international arbitrations when arbitrators are required to look to international law principles as the basis for their decisions. For example, suppose a foreign investor sought to develop land but was prevented from doing so because of a failure to prepare an environmental impact assessment prior to commencing development activities. If the foreign developer then pursued an expropriation claim under an investment treaty, the international equivalent of a government taking, recognition of the EIA norm as an applicable general principle would help blunt such challenges by supporting the legitimacy of EIA requirements.

Finally, the EIA norm would bind international organizations and automatically become part of national law in monistic legal systems, legal systems that recognize international law as part of their national law systems. For systems that have already adopted the EIA norm, the international law nature of the EIA norm would reinforce its legitimacy, provide a supplementary legal basis for EIA processes, extend the scope of existing EIA requirements, and provide interpretive gloss when national law is ambiguous.

For the United States, it could also settle a significant area of uncertainty with respect to NEPA’s extraterritorial applicability. Since NEPA has been construed to apply only within U.S. territory and Antarctica, EDF v. Massey, 986 F.2d 528 (D.C. Cir. 1993), assessment of the environmental effects of major federal actions abroad are performed as a matter of executive branch discretion under Executive Order 12114. As the case strengthens for positioning the EIA norm as binding international law, this could justify requiring impact assessments abroad as a matter of international law. Of course, skepticism by U.S. officials would likely create resistance to such an outcome, just as continued U.S. skepticism toward other new environmental norms such as the human right to a healthy environment and to a right to water and sanitation has shown. However, with the United States’ strong commitment to international law, acceptance may be just a matter of time.

NEPA’s Enduring Value

More than five decades ago, the U.S. Congress invented a new legal norm that has since become the cornerstone of the U.S. environmental law system. It was never intended as the be-all and end-all tool to solve the nation’s environmental problems, and it certainly has not been able to do so by itself. Nevertheless, NEPA’s conquest of the globe has shown the enduring value of this invention not only for the United States but the entire world.