The Obligation of EIA in the International Jurisprudence and Its Impact on the BBNJ Negotiations

Abstract

Environmental impact assessment (EIA) has been widely recognized as a crucial instrument for sound decision-making that will promote environmental conservation and sustainable development. International jurisprudence has clarified the obligation of EIA under customary international law, especially concerning its legal status, threshold standards, and procedural requirements, as well as the issue of State responsibility. As suggested by this article, international tribunals tend to adopt a procedural-oriented and State-based approach regarding the obligation of EIA, leaving more discretion to the States pursuing the proposed activities. This approach is insufficient to realize the role of EIA in fostering sound decision-making. As for the BBNJ negotiations, in light of the legal status of the Area in international law and the established rules governing the issues of EIA, especially the three Regulations and Recommendations adopted by ISA, the future implementation agreement should reinforce international regulations regarding the substance and implementation of EIA obligations.

1. Introduction

Impact assessment refers to the process of identifying the likely consequences arising from a current or proposed activity [1]. Environmental impact assessment (EIA) has been widely recognized as a crucial instrument for sound decision-making that will promote environmental conservation and sustainable development. EIA is an issue affecting both science and law, and the assessment should be based on environmental data and scientific knowledge. Regarding its legal aspect, a wide range of international treaties and instruments have stipulated the requirement of EIA. Especially, this obligation has been identified as one subject for the ongoing negotiation of an international agreement concerning the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction (BBNJ) [2]. Nevertheless, most multilateral treaties merely establish a general obligation to carry out EIAs, and the terms used are relatively abstract and vague, leading to some obstacles in practical application. Although certain international treaties and instruments contain more detailed provisions, the number of contracting Parties is limited, and most other instruments by themselves lack legally binding force [3](para. 205).

As environmental disputes increase, the International Court of Justice (the Court) is currently facing more opportunities to address the issue of EIA, for instance, in the Nuclear Tests case (1995), the Gabçíkovo-Nagymaros Project case (1997), the Pulp Mills case (2007), and Certain Activities and Construction of Road cases (2015). Especially in the Pulp Mills case and the Certain Activities and Construction of Road cases, the Court expounds on the specific requirement of EIA. In addition, the Seabed Disputes Chamber of the International Tribunal for the Law of the Sea (ITLOS) analyzed this obligation in its advisory opinion concerning the responsibilities of States for activities in the International Seabed Area (the Area). Other international tribunals have also addressed EIA-related issues [4]. In most cases, due to the lack of treaty obligations binding both Parties, international jurisprudence clarifies the obligation of EIA from the aspect of customary international law. These judicial and arbitral practices would provide references for interpreting and applying relevant international treaties. Furthermore, the future law-making process could codify the customary rules identified by international tribunals [5].

In the following sections, this article examines international jurisprudence pertaining to EIA obligations, and analyzes the international tribunals’ elaboration on issues such as its status in international law, threshold standards, requirements, and State responsibility. This article attempts to find out whether the determinations made by international tribunals are sufficient to protect the environment and promote sustainable development. In its conclusion section, this article discusses the influence of EIA obligations under customary international law upon the BBNJ negotiations.

2. The Legal Status of EIA Obligations

Regarding the status of EIA obligations in international law, the Court has observed that undertaking EIAs is an obligation under general international law when the planned industrial activities are likely to cause significant transboundary damage, especially to States’ shared resource [3](para. 204). Subsequently, this position was reaffirmed, and the Court added that the application of this principle was not limited to industrial activities but extended to any planned activities that may have a similar impact on the environment [6](para. 104). In addition, the ITLOS Seabed Disputes Chamber clearly expressed that customary international law requires States to fulfill the obligation of EIA [7](para. 145). For the determination of customary international law, judicial decisions—particularly those delivered by the Court—are recognized as being of crucial importance [8].

Apparently, the aforementioned cases do not conform to the typical approach to identify customary international law, namely evaluating the State practice and opinio juris pertaining to the obligation of EIA. Nevertheless, due to the widespread acceptance of EIA as a legal obligation, this judicial determination regarding its legal status does not give rise to many controversies or oppositions [9](p. 222). The relevant State practice could be traced back to the National Environmental Policy Act adopted by the United States in 1969, and since then, the requirement of EIA has been established in domestic legislation worldwide, including in China, the United Kingdom, Canada, Japan, Australia, India, and other countries [10]. At the international level, this obligation is stipulated by several multilateral treaties, including the Convention on Biological Diversity (CBD), the United Nations Convention on the Law of the Sea (UNCLOS), and the Convention on Environmental Impact Assessment in a Transboundary Context (Espoo Convention). In addition, some guidelines or recommendations concerning EIA have been adopted by United Nations Environment Programme (UNEP) [11], the Food and Agricultural Organization (FAO) [12], the Conference of the Parties to CBD [13], and other international organizations [9](p. 223). Notably, in a resolution entitled “International Cooperation in the Field of the Environment”, the United Nations General Assembly endorsed the Goals and Principles of EIA adopted by UNEP [14]. Only one State voted against the resolution, while 149 States supported it [15]. Based on the national and international practice, it could be concluded that there is not much doubt concerning the nature of the EIA obligation as customary international law.

There are underlying reasons for the general practice of EIA obligations. Given the irreversible nature of environmental damage and the inherent constraints in the mechanism of reparation, a certain degree of vigilance and prevention is required to protect the environment [16]. As a rule of custom, the origins of the duty of prevention lie in each State’s obligation to exercise due diligence within its territory [3](para. 101). No State should knowingly allow the use of its territory to the detriment of other States [17]. Consequently, before engaging in an activity with the potential of such adverse effects, the duty of due diligence requires States to assess the risk posed by the planned activity, which could trigger the requirement to undertake an EIA [6](para. 104). This could be the reason why international tribunals did not follow the conventional approach to prove the legal status of EIA obligation, since the origin of this obligation has acquired the status of customary international law.

3. The Threshold for EIA

Although the obligation of EIA is required by customary international law, it remains vital to examine whether an EIA is necessary for all proposed activities and, if not, under what circumstances a State is obligated to carry out an EIA. This issue concerns the threshold for EIA. According to the determinations of the Court, a State is obliged to undertake a preliminary assessment in order to determine whether its planned activity poses a risk of significant damage to other States [6](paras. 153-154). Consequently, first, the term “risk” implies that the necessity of an EIA is irrelevant to the question of whether the proposed activities indeed cause damage to the environment [18]. In other words, a State cannot justify its violation of the EIA rules on the grounds that no harm occurs. Second, the risk should be of a significant nature. If such a degree of risk exists, an EIA is required; otherwise, it is unnecessary. This process is known as screening [19]. For instance, in the Certain Activities and Construction of Road cases, Costa Rica asserted that Nicaragua did not undertake an EIA for its dredging activities. In response, Nicaragua maintained that it had studied the effects caused by its operations and concluded that the boundary river and the wetland nearby would not be significantly affected. After examining the evidence, especially the opinion of experts, the Court found that no such risk was proved. In the absence of the risk as required by international law, Nicaragua was thus not obliged to undertake an EIA [6](para. 105). Nevertheless, it should be noted that experts from both Parties concurred with the findings of Nicaragua’s preliminary evaluation, the fact of which is relatively unique in international dispute settlement.

This threshold for EIA is not only supported by international jurisprudence, but also embedded in international treaties and instruments, including Article 206 of UNCLOS, Article 14 of CBD, Article 2.2 of the Espoo Convention, and Article 17 of the Rio Declaration. Yet, how to determine the level of the risk posed by a proposed activity? The answer to this question is sometimes the primary point of disagreement between the Parties. For example, the Certain Activities and Construction of Road cases concern not just the legality of Nicaragua’s dredging activities, but also Costa Rica’s road construction activities. Both Parties held clearly opposing positions as to whether an EIA was necessary for Costa Rica’s road construction [6](para. 154).

“Significant” is a relatively abstract and ambiguous term, the interpretation of which depends heavily upon the facts of each case [20]. According to international jurisprudence, the State pursuing the planned activity is required to undertake a preliminary assessment to evaluate the degree of risk [6](para. 154). Nevertheless, this issue is not entirely under the discretion of the State concerned. To achieve the objectives of EIA, it is necessary to establish some objective criteria to be followed in the preliminary assessment, thereby preventing the abuse of power by States to circumvent this obligation. In this regard, international jurisprudence indeed provides some factors of reference. In the Certain Activities and Construction of Road cases, to assess the degree of risk posed by the road construction, the nature, magnitude, and context of the works were considered by the Court [6](para. 155). First, the scale of the construction was substantial, with a length of nearly 160 km, running along the river for 108.2 km. Approximately half of the road was entirely new construction. Second, a considerable section of road was located nearby the riverbank and would frequently be constructed on slopes. Third, a significant portion of the works would take place in formerly forested regions, where the occurrence of natural hazards was frequent. Lastly, the proposed road would traverse or be adjacent to wetlands of international significance, where the environment was particularly sensitive. All these elements have the potential to exacerbate the risk of damage to the environment from the construction. The Court consequently concluded that the risk was significant enough to warrant an EIA [6](paras. 155-156).

In practice, the threshold for EIA could be established through a variety of mechanisms, such as listing categories of activities with potential to cause significant effects, listing areas of special importance or sensitivity, listing categories of resources, undertaking a preliminary assessment of the risk, or proposing certain criteria for reference [11]. In contrast to the practice of the Court, some international instruments, such as the Espoo Convention, adopt a project-oriented approach concerning the threshold for EIA. The Appendix I of the Espoo Convention identifies certain categories of activities, which are presumed to possess “significant” risk and thus warrant an EIA. As for other activities, States are required to evaluate the necessity of EIAs on a case-by-case basis. In addition, Appendix III to that Convention sets forth the general criteria to evaluate the impact caused by a proposed activity, including its size, location, and effects. The threshold standards established by the Espoo Convention are more specific and explicit, which would further restrict the discretion of States. Nonetheless, given the limited number of participating States, it is difficult to regard the mechanism established by the Espoo Convention as reflecting international custom and could thus bind non-Parties [21].

Since the facts of cases before international tribunals vary, it would be impractical to provide a comprehensive list of activities comparable to those outlined in the Espoo Convention. In spite of this, the general criteria established in the Convention are similar to those considered by the Court. Thus, although the determinations of the Court are primarily premised upon the specific facts of each case, the nature, magnitude, and context of the proposed activities could serve as guidelines for determining whether an EIA is required. Nevertheless, due to the nature of the threshold for EIAs, the planning States still enjoy a wide margin of discretion in determining whether an EIA is required under customary international law.

4. The Procedural and Substantive Obligations of an EIA

After ascertaining the threshold for EIAs, another issue to be studied concerns the specific requirements of an EIA, including the minimum essential elements of the assessment, the basic content of EIA documents, the procedure to be followed by an EIA, and the influence of EIA outcomes on decision-making. The obligation of EIAs could be considered from procedural and substantive aspects [3](para. 206).

4.1. The Procedural Obligations of EIAs

First, as a corollary of the obligation of due diligence to prevent serious transboundary environmental damage, States are required to conduct EIAs before the commencement of programs [3](para. 204). For instance, without assessing the risk of future damage, Costa Rica merely conducted several post-construction studies about the effects of the built road on the environment [6](paras. 160-161). Therefore, the Court determined that Costa Rica’s research failed to satisfy the requirement of the EIA under international law. Second, the obligation of EIAs is of continuous nature and is not a one-off requirement. As noted in the Pulp Mills case, once a proposed program has begun, the State concerned is required to continuously monitor its environmental impacts for the duration of the project, if necessary [3](para. 205). Third, States should adduce that an EIA has indeed been carried out [6](para. 154). States are thus obliged to disclose or notify the results of EIAs. Finally, supposing the risk is confirmed by an EIA, as required by the duty of due diligence, the State pursuing the proposed activities must fulfill the obligation of notification and consultation with States that will potentially be affected, in order to determine the preventive and mitigating measures [6](para. 104).

Notably, international jurisprudence outlines the procedural requirements of EIAs, which are essentially consistent with the provisions of Articles 204 to 206 of UNCLOS. Subject to the facts of each case and the claims of the Parties, international decisions still leave many crucial issues to be resolved, such as the means of publication, public participation, and the review of third parties. Most importantly, the obligation of an EIA is primarily procedural rather than substantive. Even if the outcome of an EIA reveals the degree of risk specified by international law, the obligations of the State concerned are restricted to disclosure, notification, and consultation; customary international law does not seem to define the effect of EIAs on decision-making. To fulfill the obligation of consultation, interested States are obliged to exchange views to determine the preventive and mitigating measures. An obligation to negotiate does not, however, imply an obligation to reach an agreement [3](para. 150). Decision-makers are consequently not required to restrain their decisions to avoid harmful effects [22], hence, international law may prevent uninformed decisions but not unwise ones [23]. To a considerable extent, an EIA is more of a reference than a decisive component to States’ decision-making processes [9](p. 226), which weakens its functional role in preventing and minimizing the potential deleterious impact to the environment in the transboundary context.

4.2. The Substantive Obligations of EIAs

As the obligation of an EIA is generally accepted, the Parties to a dispute typically would not challenge the necessity of an EIA; instead, most disputes concentrate on whether the environmental impacts have been adequately assessed [24]. Nevertheless, the Court has repeatedly noted that the scope and content of EIAs are not specified in general international law. Consequently, the content of the EIA is left to each State to decide through domestic laws and authorization procedures [6](para. 104). For instance, Argentina argued in the Pulp Mills case that Uruguay’s EIA did not consider the alternative locations for the pulp mills and failed to consult the population who might be adversely affected. In support of its arguments, Argentina referred to the Espoo Convention and the Goals and Principles adopted by UNEP [3](para. 118). Nevertheless, the Court observed that neither Argentina nor Uruguay was State Party to the Convention, and the UNEP instrument was not legally binding on them [3](para. 205).

It is noteworthy that even though the Court did not support Argentina’s arguments in that case, it still examined whether Uruguay considered the alternative sites and consulted the affected population [3](para. 206). In addition, the determinations of the Court still offer some criteria to evaluate the implementation of EIAs. First, an EIA should assess the future risk, rather than the impact that the activity has already caused ex post facto [6](paras. 160–161). Second, when a State determines the specific content of an EIA for each individual case, several factors should be taken into account, such as the nature and scale of the planned activities, the likelihood of the adverse environmental impact, and the requirement of due diligence [3](para. 205). For instance, in the Kishenganga case, India and Pakistan have presented significantly different assessments concerning the environmental impact of the project in question. Pakistan conducted more comprehensive research, whereas India only considered a limited number of indicators. The arbitral tribunal began by noting that there was no single correct method to conduct an EIA. Nonetheless, given the magnitude of the project, as well as the complexity of the local ecosystem, the tribunal found that the assessment conducted by Pakistan was more appropriate for the case [4]( paras. 97–101). Third, even though a State can determine the content of its EIA per its national laws or internal authorization procedure, this discretion cannot exempt it from the international obligation to conduct an EIA once the threshold is reached [6](para. 157). However, it can be found that most of the criteria provided by the Court are still too general and abstract.

Consequently, the Court has adopted a State-based approach regarding the substantive aspects of EIAs, leaving more discretion to States pursuing the proposed activities. This position of the Court is perhaps debatable. First, it is unrealistic to expect decision-makers to be absolutely neutral about the implementation of the EIA [25]. In addition to the need for environmental protection, they have other concerns, especially economic and resource interests. Moreover, as a legal mechanism with widespread practice since the 1970s, some established rules for EIAs have likely been developed at the national and international levels [26]. Therefore, the Court should explore more to identify some minimum standards for the substantive aspects of the EIA obligation. Some international instruments set out more detailed provisions concerning this issue. Appendix II of the Espoo Convention, for instance, lists the minimum information to be contained in an EIA document, including a description of the planned activity and its objective, a description of alternative options, a description of the environment, a description of the potential impacts, a description of mitigation measures, and a listing of knowledge gaps and uncertainties. Furthermore, Principle 4 of the UNEP Goals and Principles specifies the minimum information required for an EIA, which is quite similar to those provided in the Espoo Convention. These provisions could provide reference for summarizing the general rules of international law.

5. State Responsibility for Breach of EIA Obligations

As suggested above, international custom obliges States to conduct EIAs when certain thresholds are met. A violation of this obligation would therefore constitute an internationally wrongful act for which the responsible State should bear the responsibility [27]. The Draft Articles on State Responsibility for Internationally Wrongful Acts (ARSIWA) specifies the content of State responsibility in Part Two [28](p. 86). Currently, ARISWA is simply an instrument drafted by the International Law Commission (ILC) and has not yet been adopted as an international treaty. Nonetheless, the practice of international tribunals has endorsed that most provisions of ARSIWA regarding the content of responsibility reflect international custom and hence are legally binding [29]( paras. 152–153). With respect to the corresponding legal consequences, the responsible State should cease its wrongdoing (Article 30 of ARSIWA) and provide full reparation for the injury caused thereby (Article 31 of ARSIWA) [28](p. 87). According to Article 34 of ARISWA, reparation could take various forms, including satisfaction, restitution, and compensation, either separately or jointly. As for a breach of EIA obligations, the injured State may claim various forms of state responsibility in practice [6](paras. 224–227). The appropriate form of State responsibility should be determined by the circumstance of each case, bearing in mind the specific nature and scope of the injury [30].

To begin with, according to the long-established practice, satisfaction is the remedy for moral and non-material injury to States [31](para. 122). A decision of international tribunals declaring the wrongfulness of the State’s act is a typical form of satisfaction [28](p. 106). Since the Court primarily establishes the procedural obligations of EIAs, a declaration that the responsible State violates its obligation to undertake an EIA as required by international law is therefore an appropriate measure to satisfy the injured State [6](para. 224).

Regarding restitution and compensation, the Court stresses that they are primarily for the relief of material damage [28](p. 92). Furthermore, if restitution is materially impossible or results in disproportionate burdens to the benefits, other forms of reparation should be considered [29](paras. 152–153). Therefore, restitution should be commensurate to the damage, attaching special attention to the nature of the relevant wrongdoing [3](para. 274). As mentioned above, the obligation of an EIA is primarily of a procedural nature, and general international law sets out few restrictions on its content and scope. Therefore, even if a State fails to fulfill the obligation of an EIA, but there is no evidence to prove that its activity has caused significant transboundary damage or violated other substantive obligations of international law, neither restitution nor compensation would quality as an acceptable form of reparation [6](para. 226). As in the Pulp Mills case, although Uruguay violated the procedural obligations of the EIA by constructing the mills, it has not been established that the operation of the mills breached any substantive obligations. Therefore, the Court found that dismantling the mills would not be a suitable remedy for the violation of procedural requirements. On the same grounds, Argentina’s claim for compensation for alleged injuries was declined [3](paras. 275–276).

Finally, in the event a State fails to undertake an EIA prior to the planned activity, should it cease the ongoing activity and provide certain assurances and guarantees that the wrongful act will not be repeated? Only when an internationally wrongful act is ongoing should the responsible State be obligated to end it [31](para. 113). For instance, due to the absence of an appropriate EIA, Nicaragua requested the Court to order Costa Rica to stop the road construction. But this request was denied, and the main reason appears to be that nothing has proved that the construction indeed caused any material damage. In addition, the Court noted the measures taken by Costa Rica to mitigate the adverse effects on the environment [6](paras. 227–228). As for the necessity of assurances and guarantees, these forms of remedy aim to restore confidence in the future, but they are not always required [28](p. 89). The Court would only order the State concerned to make such assurances and guarantees if the case so warranted. It cannot be assumed lightly that the responsible State will repeat the wrongdoing in the future; rather, it must be presumed to have good faith [32]. Accordingly, the Court denied Argentina’s request that Uruguay provide adequate guarantees in the Pulp Mills case [3](para. 278).

Due to the fact that international jurisprudence does not specify the substantive obligations of EIAs, under customary international law, the State’s responsibility for a violation is generally restricted. Especially, the injured State cannot claim restitution or monetary compensation for a mere breach of procedural obligations, and the primary obligation of an EIA is procedural in nature. In the absence of confirmed evidence suggesting that the responsible State’s subsequent conduct will not comply with the requirements of the EIA, the responsible State is not even required to suspend ongoing activities. This restricted State obligation could further undermine the environmental protection function of EIAs. Faced with the constraints in the mechanism of responsibility, in order to prevent the irreversible damage caused by the activity in question, States could try to request provisional measures from international tribunals prior to the commencement of the activity, requiring the planning State to suspend its activity and carry out an EIA [33].

6. The Impact on BBNJ Negotiations

The aforementioned decisions elaborate on the obligation of EIAs, which can serve as general guidance for various transboundary activities. In addition, the ITLOS Seabed Disputes Chamber noted that wordings used by the Court are sufficiently broad to regulate activities in areas beyond national jurisdiction (ABNJ), especially as the judgments make explicit reference to the “shared resource” [7](para. 148). From the point of customary international law, the well-established rules regarding EIAs, as reflected in international jurisprudence, would affect the ongoing BBNJ negotiations. Some negotiating States indeed tend to favor this State-based approach adopted by the Court, opposing more international regulations and monitoring for EIAs in the context of BBNJ [34]. The further revised draft text of the agreement on BBNJ indicates that international tribunals’ interpretations and applications of EIA obligations have been accepted in many respects, especially the thresholds for EIAs and certain procedural requirements [35].

Articles 204, 205, and 206 of UNCLOS are directly related to the subject of EIAs in the BBNJ negotiations. Especially, Article 206 addresses the assessment of the potential effects of activities, Article 205 concerns the obligation of publication, and Article 204 requires States to monitor the risks or impacts arising from marine pollution. The terms used in these articles are sufficiently broad to cover ABNJ activities. These articles constitute the foundation and guiding principles for the current law-making process [36]. However, the key terms therein remain too abstract and imprecise for application. For instance, it is necessary to determine whether there are “reasonable grounds”, whether the pollution is “substantial”, whether the changes are “significant”, and what potential effects should be assessed. As discussed, international jurisprudence could provide insight into the interpretation and application of the above articles.

Nonetheless, ABNJ has a special legal status, especially the Area. To promote equitable and sustainable development of the Area and its resources, the principle of common heritage of mankind is established; therefore, activities therein could not primarily depend on the discretion of individual States. Currently, mechanical removal without initial processing at the seabed is recognized as the most applicable technology for deep ocean mining operations [37](p. 2). This technique may cause sediment disturbance and plume perturbations, which have the potential to disrupt the fragile ecosystem of benthic flora and fauna [38]. In response to these problems, the International Seabed Authority (ISA) adopted three Prospecting and Exploration Regulations concerning polymetallic nodules [39], polymetallic sulphides [40] and cobalt-rich ferromanganese crusts [41]. In 2013, it also adopted the Recommendations for the Guidance specifically on EIAs [37]. These documents elaborate on the EIA obligations for activities in the Area. First, the Recommendations for the Guidance list the activities requiring and not requiring an EIA, establishing clear threshold criteria for conducting EIAs. For instance, activities requiring a prior EIA include the use of systems that can cause artificial disturbances on the sea floor, testing of collection systems and equipment, and drilling activities utilizing onboard drilling rigs [37](pp. 6–8). Second, the content and implementation of EIAs are further specified in detail. These instruments list the information regarding the proposed exploration program that should be submitted to ISA [37](pp. 8–9), especially the necessary data for the establishment of an environmental baseline with which the impact of future activities can be measured, including data pertaining to physical oceanography, geology, chemical oceanography, sediment properties, biological communities, bioturbation, and sedimentation [37](pp. 4–5). The environmental monitoring and evaluation program should include proposals for impact reference zones and preservation reference zones [37](pp. 8–9). More importantly, ISA strengthens international cooperation and regulations. For instance, according to Article 31 of the Regulations on Prospecting and Exploration for Polymetallic Nodules, contractors and sponsoring States should fulfill the obligation to cooperate with ISA to establish and implement relevant program. In particular, data and information on EIAs are required to be reviewed by the Legal and Technical Commission and the Council of ISA when exploration applications are submitted, as indicated by Articles 20, 23, 24 of the Regulations on Prospecting and Exploration for Polymetallic Sulphides in the Area.

The aforementioned instruments are not international treaties adopted by States. Furthermore, their application is limited to prospecting and exploration activities for resources in the Area and therefore cannot cover all ABNJ activities. Nevertheless, in its advisory opinion, the Chamber of ITLOS gave considerable weight to the above provisions of the Regulations and Recommendations for the Guidance, finding that the indications therein added “precision and specificity” to EIA obligations for activities in the Area [7] (para. 149). In addition, as discussed above, the provisions of these instruments regulate the consideration and approval of applications for exploration. Hence, their influence on the obligation of EIAs could hardly be underestimated.

7. Conclusions

Based on the above analysis, international jurisprudence provides a certain reference for interpreting and applying EIA obligations. First, under certain conditions, customary international law requires States to conduct EIAs. Second, the threshold for conducting an EIA is that the planned activity poses a risk of significant damage to the environment of other States. The Court also provides factors of reference to ascertain whether an EIA is required in specific cases, including the nature, magnitude, and context of the proposed activities. Third, procedural obligations of the EIA require States to conduct prior and continuous assessments, disclose the outcome of the EIA, and fulfill the obligations of consultation and notification when a risk of significant transboundary damage is confirmed. These requirements could urge States to adopt necessary steps to prevent serious transboundary damage and limit their abuse of power to circumvent the obligations of EIAs to some extent.

On the other hand, international jurisprudence provides few detailed references for the content and scope of EIAs. Especially, even though an EIA reveals the risk specified by international law, States are not obliged to abandon the planned activities in question. In addition, for the breach of EIA obligations, satisfaction is usually the sole form of remedy available, whereas claims for restitution or compensation are rejected. On the whole, international jurisprudence has adopted a State-based and procedural-oriented approach regarding the obligation of EIAs, leaving more discretion to States pursuing the proposed activities. In this sense, EIAs primarily serve as an aid to decision-making rather than a determining factor. This approach is insufficient to realize the role of EIAs in fostering sound decision-making.

In the ongoing BBNJ negotiations, some States tend to support the approach adopted by international jurisprudence, opposing extensive international regulations and monitoring of EIAs. From the revised draft text of the agreement on BBNJ, the practice of international tribunals indeed exerts certain impacts on the law-making process, especially concerning the thresholds for EIAs and some procedural requirements. Nevertheless, in light of the special legal status of the Area, as well as its fragile ecosystem, adherence to the approach under customary international law is likely to pose a significant risk of harm. Therefore, activities in the ABNJ should be subject to more international regulations, such as developing global minimum standards and guidelines, refining the procedural process, detailing the content of EIA documents, and enhancing the review and monitoring of the Legal and Technical Body. Even if the new agreement still sets out principles and abstract provisions concerning EIAs, the effect of the established rules adopted by ISA could hardly be underestimated.