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The Certain Activities case: what implications for the no-harm rule?

Kerryn Anne Brent

Keywords: no-harm rule; transboundary harm; prevention; due diligence

The customary law duty to prevent significant transboundary harm and harm to the global commons (‘no-harm’ rule) has developed considerably since it was first enunciated in the 1938/1941 Trail Smelter arbitration. This article reflects on this development and analyses what implications the 2015 Certain Activities case has for existing understandings of the no-harm rule. The International Court of Justice (ICJ)'s judgment provides greater clarity concerning procedural obligations flowing from the no-harm rule by establishing a positive obligation to ascertain risk and a sequence in which procedural obligations arise. However, it raises questions concerning the nature of the substantive obligation under the no-harm rule. Specifically, whether breach of the substantive obligation is subject to establishing that an activity has resulted in significant transboundary harm. The ambiguity in the Certain Activities case highlights the need to further clarify and develop the content of the no-harm rule to better enable it to contribute to the governance of contemporary transboundary and global environmental problems.

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1 INTRODUCTION

It is a well-established rule of customary international law that states have a duty 1 to prevent significant transboundary harm and harm to the global commons. This duty, otherwise known as the ‘no-harm’ rule, can be traced back to the decision in the 1938/1941 Trail Smelter arbitration. 2 It is founded on the principle of good-neighbourliness and the sovereign rights of states. 3 In 1996, the International Court of Justice (ICJ) affirmed the no-harm rule as a principle of customary international law in its advisory opinion on the Legality of the Threat or Use of Nuclear Weapons (Nuclear Weapons Advisory Opinion). 4 The no-harm rule has also been incorporated into numerous international environmental agreements 5 and is considered by legal scholars to be the ‘cornerstone of international environmental law.’ 6

The no-harm rule is general in nature and binding on all states. For this reason, the no-harm rule has the potential to enable international law to respond to transboundary and global environmental issues that are not adequately addressed by international treaty law. 7 In recent years, legal scholars have considered the potential of the no-harm rule to form the basis of a claim for state responsibility for climate change damage and other complex forms of transboundary pollution. 8 Legal scholars have also identified the no-harm rule as a potential means of enabling international law to respond to the risks of transboundary and global environmental side effects of proposed geoengineering technologies. 9 These are proposals to develop technology to manipulate the global climate system on a large scale to address climate change, 10 many of which are not explicitly governed by existing international agreements. 11 The potential of the no-harm rule to respond to global environmental issues such as climate change and geoengineering highlights a need to better understand the scope of this rule and what states must do to discharge their obligations under it.

To this end, in 2011 the Pacific Small Island Developing State of Palau requested that the UN General Assembly sought an advisory opinion from the International Court of Justice on the meaning of the no-harm rule in the context of climate change. 12 The request was unsuccessful, 13 but nevertheless highlights how ICJ decisions (both in contentious cases and advisory opinions) might play an important role in developing a clearer understanding of the no-harm rule in light of contemporary environmental concerns. In accordance with article 38 of the Statute of the International Court of Justice, decisions of international courts and tribunals are not a primary source of international law. However, as noted by Birnie, Boyle and Redgwell, they ‘provide the most authoritative guidance on the state of the law at the time they are decided.’ 14 Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) & Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (‘Certain Activities’ case) 15 involved two disputes that were joined by an Order of the Court in 2013. 16 The disputes concerned activities on behalf of both parties in the vicinity of the San Juan River, which runs along the border between Nicaragua and Costa Rica. Both parties alleged that the other had breached its obligations under customary international law concerning transboundary harm. The Certain Activities case therefore presented the ICJ with an opportunity to provide an authoritative account of the no-harm rule and clarify its content. 17

This article analyses how the decision in the Certain Activities case contributes to existing understandings of the no-harm rule. The judgment provides a clearer picture of procedural obligations that flow from the no-harm rule, such as the duty to conduct an environmental impact assessment (EIA) and the duty to notify and consult with potentially affected states. It does so by establishing a preliminary obligation to ascertain risk and a sequence within which procedural obligations arise. However, the judgment is far less clear when it comes to the substantive obligation under the no-harm rule. The approach of the Court appears to conflict with the understanding that the substantive obligation provides states with a duty of due diligence, and that breach therefore is not contingent on proof of harm. It also raises questions regarding the connection between the substantive obligation and procedural obligations. This article proposes that further clarification of the no-harm rule is needed to bolster the no-harm rule's preventative capacity and better enable it contribute to the protection of the global environment.

This article proceeds as follows. In order to analyse the contribution of the Certain Activities case to current understandings of the no-harm rule, this article begins in section 2 by outlining its historical development from the Trail Smelter arbitration. Section 3 analyses the judgment of the ICJ in the Certain Activities case and considers how it contributes to existing understandings of the no-harm rule.

2 THE NO-HARM RULE PRIOR TO THE CERTAIN ACTIVITIES CASE

In order to assess the contribution of the Certain Activities case to the understanding of the no-harm rule, it is first necessary to establish the content of the rule and how it was interpreted by states, legal scholars and international jurists prior to this case. As a principle of customary international law the content of the no-harm rule is not clearly formulated in a single document, unlike rules contained in international agreements. The content of the no-harm rule is instead evidenced in numerous documents, including the judgments of international courts and tribunals, 18 the pronouncements of states in pleadings, 19 diplomatic correspondence and the decisions of international bodies such as the UN General Assembly. 20 Furthermore, the content of the no-harm rule is not static – it has continued to evolve over time. It is useful to examine the historical development of the no-harm rule to gain a clear picture of its current content, and understand the implications of the Certain Activities case. This section outlines the development of the no-harm rule through prominent sources. 21 The development of the no-harm rule can be divided into three ‘phases’ based on different understandings of the no-harm rule. It is acknowledged that, to a certain extent, each phase overlaps. However, presenting the development of the no-harm rule in three phases helps to illustrates key changes in the interpretation of the no-harm rule over the past 70 years.

2.1 Phase one: The duty not to cause harm to the territory of another state

The first phase begins with the landmark 1938/1941 decision of the Tribunal in the Trail Smelter arbitration. 22 The dispute concerned transboundary air pollution produced by a zinc smelter in the town of Trail in British Colombia, Canada. Prevailing wind conditions carried sulphur dioxide fumes from the smelter downwind into the neighbouring state of Washington in the United States. 23 In 1925, residents in the area began to complain that fumes from the Trail Smelter had caused damage to their property. 24 In 1935, after a decade of unsuccessful attempts to resolve the dispute, the United States and Canada referred the matter for international arbitration. 25 By way of a bilateral agreement, the parties asked the Tribunal to establish if and to what extent the Trail Smelter should avoid causing future damage to the State of Washington. 26 The tribunal famously pronounced that:

… under the principles of international law, as well as the law of the United States, no State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties or persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence. 27

The precedential value of the Trail Smelter arbitration has been called into question by some scholars. One reason is that the Tribunal relied primarily on US domestic sources and not sources of international law in reaching this decision. 28 However, this approach appears to have been relatively uncontroversial at the time of the dispute. As there was limited international jurisprudence, the US and Canada had expressly authorised the Tribunal to ‘apply the law and practice in dealing with cognate questions in the United States of America as well as international law and practice’. 29 Other legal scholars have questioned the fact that the Tribunal's line of inquiry was shaped by bilateral agreement rather than by consideration of the general rules of international law. 30 Nonetheless, legal scholars generally agree that the no-harm rule can be traced back to the Tribunal's pronouncement. 31

The decision of the Tribunal in the Trail Smelter arbitration established three clear parameters regarding the no-harm rule. First, the no-harm rule only applied to ‘serious’ harm. Second, the no-harm rule only applied to transboundary harm to the territory of other states (as opposed to global commons areas). Third, states wishing to bring an action on the basis of the no-harm rule had to provide ‘clear and convincing’ evidence of harm. 32 It is less clear what type of obligation the decision in the Trail Smelter arbitration established. That is whether it provided states with a duty of conduct (ie due diligence) or a duty of result. As part of its decision, the Tribunal established a management regime for the Trail Smelter in order to prevent further transboundary damage occurring to Washington State. 33 This has led some legal scholars to suggest that the decision in the Trail Smelter arbitration supports a duty of due diligence. 34 That is, breach of the no-harm rule was based on the conduct of a state and not on proof of harm alone. The International Law Commission's (ILC) 2001 Draft Articles of Prevention from Hazardous Activities (Draft Articles on Prevention) also appear to follow this interpretation. 35 However, the Tribunal suggested that adherence to the regime would not necessarily absolve the Trail Smelter of liability for future damage. 36 Furthermore, as Goldie notes, the Tribunal imposed liability on Canada without proof of fault. 37 The decision of the tribunal can therefore be interpreted to support either a duty of conduct or result during this phase of the no-harm rule's development. 38

In this first phase, the no-harm rule was characterised as a tool for balancing and protecting the sovereign rights of states, rather than as a rule for protecting the environment per se. 39 This is further demonstrated by the decision of the ICJ in the 1949 Corfu Channel case. 40 The ICJ noted that a state has an obligation ‘not to allow knowingly its territory to be used for acts contrary to the rights of other States.’ 41 This statement is widely accepted by legal scholars as having affirmed the no-harm rule flowing from the Trail Smelter arbitration, even though the ICJ made no reference to that case. 42 The ICJ expressed the no-harm rule in the language of the rights of states, rather than referring to physical pollution or damage as was done by the Tribunal in the Trail Smelter arbitration. 43

This characterisation was further reinforced in the 1957 Lake Lanoux arbitration. 44 The dispute involved a proposal by France to divert water upstream along a shared waterway for the purpose of generating hydroelectricity. 45 The same volume was to be restored to the waterway so that the amount of water flowing into Spain was unaltered. 46 Spain argued that France's proposal unilaterally breached its rights under a pre-existing bilateral agreement, 47 as the flow of water would no longer be natural and would be subject to the control of France. 48 The tribunal found that France's proposal would not violate Spain's rights under the agreement as the water would be restored to the river with no evidence of any other negative impacts (ie pollution or temperature change). 49 The Tribunal hypothetically considered the application of customary international law, stating that:

… if it is admitted that there is a principle which prohibits the upstream State from altering the waters of a river in such a fashion as seriously to prejudice the downstream State, such a principle would have no application to the present case, because it has been admitted by the Tribunal, in connection with the first question examined above, that the French scheme will not alter the waters of the Carol. 50

This statement is also interpreted by legal scholars as affirming the principle of good-neighbourliness and the no-harm rule as articulated in the Trail Smelter arbitration. 51 The Tribunal's determination suggests that mere utilisation of a shared watercourse was not considered sufficient to trigger the no-harm rule: it was also necessary to establish a detrimental effect that would impact on the ability of the downstream state to utilise the shared watercourse. 52 This decision suggests that even in the case of a common environmental resource, such as a river, the scope of the no-harm rule remained bound to the rights and interests of states. However, this focus began to shift in the next phase.

2.2 Phase two: A positive duty of prevention and extending the no-harm rule to the global commons

The second phase in the development of the no-harm rule coincided with growing international concern regarding the global consequences that human activities were having on the natural environment. 53 The no-harm rule was reformulated in such a way as to place greater emphasis on environmental protection. The beginning of this phase is marked by the 1972 Declaration of the United Nations Conference on the Human Environment (Stockholm Declaration). 54 Principle 21 states that:

States have, in accordance with the Charter of the United Nations and the principles of international law, the sovereign right to exploit their own resources pursuant to their own environmental policies, and the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction (emphasis added).

The Stockholm Declaration is a ‘soft law’ agreement, and is not legally binding or enforceable. 55 Nonetheless, Principle 21 is widely recognised by legal scholars as reiterating the no-harm rule under customary international law. 56 Principle 21 maintained the balance between the sovereign rights of states that was prominent in the first phase of the no-harm rule's development. However, it reformulated the no-harm rule to include a new emphasis on environmental protection.

Principle 21 extended the no-harm rule to include harm to the global commons in addition to transboundary harm to the territory of other states. 57 It also extended the no-harm rule with respect to the ‘jurisdiction or control’ of states. 58 That is, it not only applies to the activities of states within their own territory, but also to activities carried out on ships or aircraft registered within a state. 59 As such, it is also possible that the no-harm rule may apply to the activities of corporations incorporated within a state. 60 Finally, Principle 21 reshaped the no-harm rule so that states have a responsibility to actively prevent transboundary environmental harm and harm to the global commons. 61

This new formulation of the no-harm rule was reaffirmed in Principle 2 of the 1992 Rio Declaration on Environment and Development (Rio Declaration). 62 In 1996, the ICJ acknowledged the extension of the no-harm rule to the global commons as customary international law in its Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, stating that:

[t]he existence of the general obligation of States to ensure that activities within their jurisdiction and control respect the environment of other States or of areas beyond national control is now part of the corpus of international law relating to the environment. 63

Both sources continued to emphasise the role of the no-harm rule in responding to environmental harm. However, precisely what states were expected to do to fulfil their obligations under this new formulation remained unclear. 64

The disputes in the 1974 Nuclear Tests cases draws attention to several key question regarding the scope and duty of care under the no-harm rule. 65 Shortly after the Stockholm Conference in 1973, Australia and New Zealand initiated separate proceedings against France in the ICJ concerning France's nuclear test programme in the Pacific. In a note from the New Zealand Embassy to the French Ministry of Foreign Affairs, it was noted that there was ‘widespread public apprehension that fallout from any tests in the vicinity will produce hazards to heath and contaminate food supplies, both land and marine, in the Cook Islands and indeed in New Zealand itself.’ 66 On 3 January 1973, the Australian Ambassador to Paris in a note to the French Foreign Minister stated:

In the opinion of the Australian Government, the conducting of such tests would not only be undesirable but would be unlawful – particularly in so far as it involves modification of the physical conditions of and over Australian territory; pollution of the atmosphere and of the resources of the seas; interference with freedom of navigation both on the high seas and in the airspace above; and infraction of legal norms concerning atmospheric testing of nuclear weapons. 67

France denied that its conduct breached existing rules of international law. In correspondence with the Australian Prime Minister, France stated that, as no harm had yet occurred to the territory or citizens of Australia, it ‘finds it hard to see what is the precise rule on whose existence Australia relies’. 68 France further argued that it had a right to conduct the tests on grounds of self-defence. In a letter to the Australian Prime Minister and Minister of Foreign Affairs, France highlighted that it had been invaded three times within the past century and that universal nuclear disarmament had not yet been achieved. 69 Given the ongoing security threat posed by nuclear weapons, France stated that it ‘must imperatively endow itself with the means of ensuring its security and preserving its vital interests’. 70 France also maintained that it had implemented precautionary measures to ensure the safety of neighbouring states and other states in the region. 71 Such measures included the remote location of the test site and the monitoring of global levels of radioactive contamination. 72 However, New Zealand did not consider these measures to have sufficiently cancelled out the risk of harm from nuclear radiation to other states, the atmosphere and the ocean, stating that ‘an activity that is inherently harmful is not made acceptable even by the most stringent precautionary measures’. 73

The ICJ declined to render judgment on the merits of the case and therefore did not clarify or elaborate on relevant international law. 74 Nonetheless, this correspondence highlights three important questions concerning the no-harm rule during the second phase of its development. First, what must states do to discharge their obligations under the no-harm rule? A second related question is what (if any) measures were states required to undertake to minimise the risk of future harm? As early as the Corfu Channel case and Lake Lanoux arbitration, there were indications that states may have an additional obligation to notify and consult with other states regarding the prevention of significant transboundary harm. 75 This obligation was later incorporated in the 1992 Rio Declaration, as well as the procedural obligation to conduct an EIA. 76 Yet the Rio Declaration was a soft law agreement—how these procedures related to the no-harm rule and their status under customary international law remained unclear. 77 The third question was how the no-harm rule interacted with other rules of international law, such as the right to self-defence. The dissenting opinions of Justices Weeramantry 78 and Koroma 79 in the 1996 Nuclear Weapons Advisory Opinion implied that the no-harm rule cannot be derogated from by other international laws, even one as paramount as the right of self-defence. However, as minority opinions they are less authoritative interpretations of the no-harm rule. These questions led into the third phase of the no-harm rule's development.

2.3 Phase three: The no-harm rule as a duty of conduct and the role of procedural obligations

The third phase of the no-harm rule is marked by the International Law Commission's (ILC) 2001 Articles on the Prevention of Transboundary Harm from Hazardous Activities (Draft Articles on Prevention). 80 The Draft Articles on Prevention are the result of over 20 years of work on behalf of the ILC to codify, clarify and progressively develop international law with regard to transboundary harm. 81 They are grounded in existing jurisprudence and other legal instruments, such as the texts of multilateral environmental agreements. 82 Essentially, the Draft Articles on Prevention are an expansive interpretation of the scope and duty of care of the no-harm rule, and procedural obligations flowing from it.

The ILC is comprised of international legal experts who act in their personal capacity and not as official state representatives. 83 As such, the Draft Articles on Prevention are non-binding on states and are technically akin to the works of prominent publicists within the hierarchy of international law sources set out under article 38(1) of the Statute of the International Court of Justice. 84 Moreover, the ILC does not clearly distinguish between codification of existing customary international law and progressive development in its projects. 85 The Draft Articles on Prevention contain a mixture of codified customary law, emerging legal principles and progressive development where state practice and jurisprudence was lacking or inconclusive. 86 Consequently, the formulation of the no-harm rule and associated procedural obligation contained in the Draft Articles on Prevention may not have entirely accorded with the understanding and practice of states at the time it was drafted. 87 Nonetheless, the Draft Articles on Prevention have significantly shaped how states, 88 jurists 89 and legal scholars 90 understand the scope of the no-harm rule and its duty of care during the third phase. The Draft Articles on Prevention have been praised for providing a more precise interpretation of the no-harm rule than previous sources 91 and several legal scholars have expressed the opinion that they reflect existing customary international law. 92

The Draft Articles on Prevention reformulated the no-harm rule focusing on activities that present a risk of future harm. The ILC's rationale for this focus was that the prevention of transboundary harm is preferable to compensation after it has occurred. 93 The duty to prevent transboundary harm is expressed in draft article 3, which states that ‘[t]he State of origin shall take all appropriate measures to prevent significant transboundary harm or at any event to minimize the risk thereof.’ 94 The Draft Articles take for granted the fact that is a foreseeable risk of transboundary harm, and do not presume that harm will actually result. 95 The scope of the duty to prevent harm includes ‘harm caused to persons, property or the environment’, but does not extend to pure economic loss. 96 The scope was further limited to activities that present a risk of transboundary harm above the threshold of ‘significant’. 97 The ILC also proposed to limit the scope of the duty to prevent harm on the basis of probability. It suggested that the duty to prevent harm only applies to activities falling within a defined ‘spectrum’, being those that present a ‘high probability of causing significant transboundary harm and a low probability of causing disastrous transboundary harm’. 98 Finally, the ILC's interpretation of the no-harm rule only applied to transboundary harm to the territory of other states and not harm to the global commons. This does not appear to have been a deliberate reflection of the scope of customary international law, but was instead a pragmatic decision made within the ILC to limit the extent of the project. 99

The duty of care under the Draft Articles on Prevention is a duty of conduct or due diligence. 100 Under a duty of due diligence, states must exert their ‘best possible efforts to minimize the risk’ of transboundary harm. 101 What is considered to be a state's best possible effort will vary depending on the probability and severity of the risk at hand. 102 In other words, the degree of due diligence required by a state is proportionate to the risk. 103 The relevant standard of due diligence may also change over time with advances in scientific understanding and technology. 104 However, the commentary to the Draft Articles states that, generally speaking, it will involve ‘reasonable efforts by a State to inform itself of factual and legal components that relate foreseeably to a contemplated procedure and to take appropriate measures, in a timely fashion, to address them.’ 105 This includes enacting and enforcing relevant domestic law policies. 106

The Draft Articles further elaborate on the meaning of the duty of due diligence. According to the commentaries to the Draft Articles ‘the duty of due diligence … is not intended to guarantee that significant harm be totally prevented, if it is not possible to do so’. 107 As such, a state would not automatically be considered to have breached the no-harm rule simply because an activity within their jurisdiction or control results in significant transboundary harm. 108 The basic standard of due diligence is informed by procedural obligations that flow from the obligation to prevent significant transboundary harm. 109 The procedural obligations formulated in the Draft Articles include the duty to cooperate, 110 the prior assessment of risk (such as conducting an EIA), 111 notification 112 and consultation with other states that are likely to be affected. 113

The duty of care in the Draft Articles of Prevention mirrored due diligence obligations under existing international agreements. 114 This duty of care was rearticulated by the ICJ in its 2010 judgment in Pulp Mills on the River Uruguay (Argentina v Uruguay) (Pulp Mills case). 115 In that case, the ICJ stated that an obligation of due diligence is:

… an obligation which entails not only the adoption of appropriate rules and measures, but also a certain level of vigilance in their enforcement and the exercise of administrative control applicable to public and private operators, such as the monitoring of activities undertaken by such operators, to safeguard the rights of the other party. 116

It also confirmed that states have a duty to conduct an EIA under customary international law and that this is an integral component of satisfying due diligence. 117 The interpretation of the duty of due diligence in the Pulp Mills case was endorsed by the International Tribunal for the Law of the Sea's (ITLOS) Seabed Disputes Chamber in Responsibilities and obligations of States sponsoring persons and entities with respect to Activities in the Area (‘Activities in the Area’). 118 The ICJ did not directly cite the Draft Articles on Prevention in the Pulp Mills case. In contrast, the ITLOS cited article 3 of the Draft Articles on Prevention in support of its interpretation of the duty of care of due diligence, thereby endorsing the ILC's interpretation of the no-harm rule. The ITLOS further noted that due diligence is a variable concept, and that the content will change depending on the context of an activity, the time at which it takes place and risks it entails. 119

The ITLOS also suggested that to satisfy the obligation of due diligence, states must also adopt a precautionary approach as per Rio Principle 15. 120 Activities in the Area therefore reinforced the clearer and more detailed understanding of the no-harm rule presented by the Draft Articles on Prevention. However, this does not automatically mean that this understanding of the duty of due diligence under the no-harm rule was shared by states.

This issue is highlighted in the Case Concerning Aerial Herbicide Spraying (Ecuador v Colombia) (Aerial Herbicide Spraying case). 121 In 2008, Ecuador initiated proceedings against Colombia in the ICJ regarding Colombia's aerial herbicide spraying programme. 122 The purpose of this programme was to destroy illegal cocaine and poppy plantations in a region of its territory that bordered Ecuador. 123 Ecuador alleged that the herbicides had drifted into its territory, causing significant transboundary harm. 124 The no-harm rule was therefore central to Ecuador's claim.

To support its interpretation of the no-harm rule, Ecuador relied heavily on the ILC's Draft Articles on Prevention, suggesting that they provided a more detailed formulation of the no-harm rule than other sources. 125 Colombia objected to this use of the Draft Articles. It submitted that these were an exercise in progressive development and did not accurately reflect customary international law. 126 Colombia claimed that few states had voiced their support for the Draft Articles as codifying existing customary law. 127 Colombia had previously conceded to the existence of an ‘obligation of due diligence to prevent or minimize transboundary harm’, but it highlighted that it and a number of other states had never accepted every detail of the Draft Articles as custom. 128 For example, Colombia did not consider itself to be bound by Draft Article 7 to conduct an EIA. 129 However, the ICJ never had an opportunity to assess the extent to which the Draft Articles on Prevention reflected customary international law. In 2013, the parties settled the dispute outside of Court by way of special agreement and the case was removed from the ICJ List. 130

The written submissions by Ecuador and Colombia indicate that the states may have agreed that they had a due diligence obligation to prevent significant transboundary harm under customary international law. However, they nevertheless suggest that some states had different understandings as to what was required to fulfil this obligation. Ecuador characterised Colombia's spraying programme as being ‘inherently hazardous’ as environmental harm, harm to humans and animals was fundamental to the nature of the herbicides being used. 131 It argued that the only appropriate way in which Colombia could minimise the risk of transboundary harm was to ‘eliminate all risk’ of the herbicide drifting into its territory. 132 Colombia argued that this interpretation transformed the duty of due diligence ‘into a virtual guarantee’ that harm would be absolutely prevented. 133 In other words, it transformed it into a duty of result. According to Colombia such a high standard of care did not accord with the ICJ's formulation of the no-harm rule in the Nuclear Weapons advisory opinion. 134

The different understandings of the no-harm rule exhibited in the Aerial Herbicide Spraying case highlight the importance of further judicial interpretation to clarity the rule's content.

3 THE CERTAIN ACTIVITIES CASE

The Certain Activities case provided the ICJ with an opportunity to consider, clarify and interpret the no-harm rule in the context of a contentious case. Before examining the judgment and its implications for the no-harm rule, the following sections provide an overview of the relevant disputes. As noted in the introduction, the judgment addresses two related disputes that were joined by order of the Court.

3.1 Background and submissions of parties

3.1.1 Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua)

This dispute concerned the alleged incursion and occupation of Costa Rican territory by Nicaragua's military in an area near the mouth of the San Juan River, which runs along the border between Nicaragua and Costa Rica towards the Caribbean Sea. In accordance with an international agreement negotiated by the parties in 1858 (1858 Treaty of Limits), the boundary between the two states runs along the bank on the Costa Rican side of the river. 135 This agreement gave Nicaragua dominion over the waters of the river, but granted Costa Rica the right to navigate the river for commercial purposes. 136 In spite of this agreement, the jurisdiction and sovereign rights of both parties had been subject to several disputes over the previous 150 years. 137

Costa Rica claimed that, on 18 October 2010, Nicaragua began to dredge the San Juan River and construct an artificial channel on the Costa Rican side of the river. 138 In its application to the Court, Costa Rica alleged that Nicaraguan soldiers had incurred into Costa Rican territory, felling trees and depositing sediment while constructing the channel. 139 It also claimed that Nicaragua established a camp which occupied approximately three square kilometres of Costa Rican territory. 140 Costa Rica therefore argued that Nicaragua had breached its sovereignty and right to territorial integrity. 141 Costa Rica also argued that Nicaragua had breached the prohibition against the threat or use of force, owing to the presence of Nicaragua's military in Costa Rican territory. 142 In its memorial to the Court, it characterised Nicaragua's actions as ‘nothing less than an invasion of foreign territory and an attempt at annexation’. 143 Part of the judgment focuses on the issue of state sovereignty. However, this will not be considered further in this article as it is a separate issue to the no-harm rule. Costa Rica further alleged that Nicaragua had breached international environmental law by failing to fulfil procedural requirements to prevent transboundary harm and the substantive obligation not to cause harm to the territory of other states. 144 Specifically, in its application to the Court, Costa Rica claimed that Nicaragua had caused ‘serious damage’ to the territory it had occupied and that the construction of the canal would ‘seriously affect the flow of water to the Colorado River’, which flows from the San Juan River. 145 Costa Rica also argued that further construction would cause additional damage to wetlands and wildlife in its territory. 146

In its Counter-Memorial, Nicaragua defended the legality of its activities. Nicaragua argued that its dredging programme was consistent with its right to maintain the navigability of the river. 147 Nicaragua also claimed that the 1858 Treaty of Limits was lex specialis and that the no-harm rule and procedural obligations flowing from it were secondary to the treaty's terms. 148 Nicaragua nonetheless stated that it had conducted an EIA in compliance with its own domestic laws and that no risk of significant transboundary harm had been identified. 149 Nicaragua therefore argued that even if customary international law applied, it had not been breached. 150

3.1.2 Construction of a Road in Costa Rica along the San Juan River (Nicaragua v Costa Rica)

This dispute concerned the construction of a road by Costa Rica within its own territory along the San Juan River. Costa Rica began construction of the road in December 2010. 151 Following commencement of construction, Costa Rica declared a state of emergency regarding Nicaragua's activities in its territory and claimed that the construction of the road was necessary for national security. 152 Nicaragua objected to the construction of the road. It claimed that significant amounts of sediment had been dumped into the San Juan River. 153 It further claimed that the felling of trees and removal of topsoil along the riverbank would lead to erosion, leading to greater sedimentation that could impact on the water quality of the river, marine life and the biodiversity of the surrounding ecosystem. 154 Nicaragua also alleged that the construction of the road might have subsequent social, cultural and economic impacts, such as impacts on fishing and ecotourism. 155

Nicaragua argued that Costa Rica had breached the no-harm rule and the procedural obligations to conduct an EIA and notify and consult with potentially affected states. 156 According to Nicaragua, Costa Rica had declared an emergency situation merely to circumvent domestic law and its international legal obligations. 157 It argued that ‘…Costa Rica has attempted to force the actual situation onto the Procrustean bed of its law's definition of “disaster” in order to justify a colossal and environmentally destructive project’. 158 Nicaragua submitted that such evocation of national law to justify an internationally wrongful act was against article 27 of the Vienna Convention on the Law of Treaties 159 and customary international law. 160

Costa Rica refuted these allegations, and maintained that the declared state of emergency exempted it from the duty to conduct an EIA. 161 Costa Rica also argued that it was under no obligation to conduct an EIA or notify and consult with Nicaragua as there was no risk of significant transboundary harm. 162 Finally, Costa Rica claimed that Nicaragua had failed to establish that significant transboundary harm had been caused to the San Juan River, or that there was a risk of this occurring in the future. 163 As such, it had not breached the no-harm rule.

3.2 Judgment

3.2.1 Procedural obligations

A key issue in both disputes was whether the parties had breached the procedural obligation to conduct an EIA. The ICJ affirmed its pronouncement in the 2010 Pulp Mills case, that states have a customary law duty to conduct an EIA for activities that pose a risk of significant transboundary harm and that this is necessary to satisfy the duty of due diligence. 164 However, the ICJ went beyond its statement in the Pulp Mills case, holding that:

… to fulfil its obligation to exercise due diligence in preventing significant transboundary environmental harm, a State must, before embarking on an activity having the potential adversely to [sic] affect the environment of another State, ascertain if there is a risk of significant transboundary harm, which would trigger the requirement to carry out an environmental impact assessment. 165

In other words, states have a positive obligation to first ascertain whether an activity poses a risk of significant transboundary harm. The Court suggested that this obligation may be satisfied by conducting a preliminary risk assessment. 166 The Court held that if the result of this initial assessment is affirmative, then a state must conduct an environmental impact assessment, the content of which should reflect the nature and magnitude of the activity in question. 167

The Court also clarified the relationship between the duty to conduct an EIA and the duty to consult and notify with potentially affected states. It stated that:

If the environmental impact assessment confirms that there is a risk of significant transboundary harm, the State planning to undertake the activity is required, in conformity with its due diligence obligation, to notify and consult in good faith with the potentially affected State, where that is necessary to determine the appropriate measures to prevent or mitigate that risk. 168

States must therefore notify and consult with other states in order to discharge the obligation of due diligence to prevent significant transboundary harm. However, this obligation only arises if the EIA confirms a risk of significant transboundary harm.

The threshold of ‘significant’ harm is key to the progression of these procedural obligations. It was the determining factor as to whether Nicaragua had breached its procedural obligations. 169 The judgment noted that in 2006, Nicaragua had conducted a study of the impacts of the dredging programme which concluded it would not significantly impact on the flow of the Colorado River. 170 The court did not provide further details, but stated that on the basis of the evidence before it, it was satisfied that the programme did not ‘give rise to a risk of significant transboundary harm, either with respect to the flow of the Colorado River or to Costa Rica's wetland.’ 171 Consequently, Nicaragua was not obliged under customary international law to carry out an EIA. 172 Nor was it obliged to further notify and consult with Costa Rica. 173 As there was no risk of significant transboundary harm, the question as to whether the 1858 Treaty of Limits created lex specialis was also a moot point. The Court merely noted that:

… the fact that the 1858 Treaty may contain limited obligations concerning notification or consultation in specific situations does not exclude any other procedural obligations with regard to transboundary harm which may exist in treaty or customary international law. 174

When considering whether Costa Rica had breached its procedural obligations, the judgment provided greater analysis as to whether there was a risk of significant transboundary harm. The Court considered the ‘nature and magnitude of the project and the context in which it was to be carried out’. 175 One factor was the proximity of the road to the river, which the Court held increased the likelihood of sedimentation. 176 The Court also took into account the fact that this risk was exacerbated by the possibility of natural disasters, such as hurricanes, tropical cyclones and earthquakes. 177 An additional consideration was that the road passed through Ramsar protected wetlands. 178 The judgment states that ‘The presence of Ramsar protected sites heightens the risk of significant damage because it denotes that the receiving environment is particularly sensitive’. 179 It was therefore held that the project posed a risk of significant transboundary harm. 180

As the project carried a risk of significant transboundary harm, it met ‘the threshold for triggering the obligation to evaluate the environmental impact of the road’. 181 Costa Rica claimed to have carried out a preliminary assessment of such a risk, however the Court was not convinced on the evidence that Costa Rica had conducted such an assessment. 182 The Court then considered Costa Rica's claim that a state of emergency exempted it from conducting an EIA under domestic legislation. The Court acknowledged its pronouncement in the Pulp Mills case that ‘it is for each State to determine in its domestic legislation or in the authorization process for the project, the specific content of the environmental impact assessment required in each case’. 183 However, it denied that this statement gives states licence to disregard their international obligations. The Court stated that:

… this reference to domestic law does not relate to the question of whether an environmental impact assessment should be undertaken. Thus, the fact that there may be an emergency exemption under Costa Rican law does not affect Costa Rica's obligation under international law to carry out an environmental impact assessment. 184

The Court further noted that Costa Rica had not sufficiently demonstrated that an emergency situation existed, as there was no imminent threat of military confrontation in the area where the road was being constructed. 185 Additionally, the construction of the road had commenced prior to the formal declaration of a state of emergency. 186 As there was no emergency situation, the Court refrained from considering whether such a situation would exempt a state from carrying out an EIA. 187 This issue remains open for the Court to examine at a later date. The Court therefore concluded that Costa Rica had an obligation to carry out an environmental impact assessment prior to the commencement of construction of the road.

The Court then turned its attention to whether Costa Rica had complied with this obligation. Costa Rica had conducted several studies on the road, but these studies were conducted after the project had been commenced. 188 The Court affirmed its pronouncement in the Pulp Mills case that states have a continuing obligation to carry out an EIA and monitor the effects of a project. 189 However, it asserted that ‘the obligation to conduct an environmental impact assessment requires an ex ante evaluation of the risk of significant transboundary harm’. 190 That is, states must conduct an EIA before commencing a project. It therefore held that Costa Rica had not complied with its obligation under customary international law to conduct an EIA prior to commencing construction of the road. 191 As Costa Rica had not fulfilled this obligation, the Court did not further examine whether it had complied with its obligation to consult and notify with Nicaragua under customary international law. 192

In his separate opinion, Judge Ad Hoc Dugard criticised the judgment for taking a more ‘scrupulous’ analysis in the Construction of a Road dispute compared to the Certain Activities dispute. 193 He argued that the Court did not follow the same approach in both disputes; if it had, it would also have found that Nicaragua's activities posed a significant risk to Costa Rica's wetlands. 194 According to Dugard, the Court should have taken into consideration Ramsar wetlands within Costa Rican territory as it had in the Construction of a Road dispute. 195 By the Court's own reasoning, the wetlands should have lowered the threshold level for ‘significant’ transboundary harm. 196 This is an important difference, but it appears to have been the result of a different approach to evidence rather than a different formulation of the procedural duties flowing from the no-harm rule. The Court provided more detail of its assessment of relevant evidence in Construction of a Road, but its analysis in Certain Activities still followed the same logic. That is, it was underpinned by an assessment of whether there was a risk of significant transboundary harm.

3.2.2 Substantive obligation

The Court's examination as to whether Costa Rica and Nicaragua had breached the substantive obligation under the no-harm rule revolved around whether the activities of both states had caused significant transboundary harm. The judgment is once again brief concerning the dredging activities of Nicaragua. The Court recalled its statement in the Pulp Mills case that:

… under customary international law, ‘[a] State is … obliged to use all the means at its disposal in order to avoid activities which take place in its territory, or in any area under its jurisdiction, causing significant damage to the environment of another State’. 197

The judgment does not consider what (if any) means Nicaragua undertook to prevent significant harm to the territory of Costa Rica. It merely held that Costa Rica had failed to establish that Nicaragua's dredging programme caused harm to its territory. 198 As there was no significant transboundary harm, the Court concluded that Nicaragua had not ‘breached its obligations by engaging in dredging activities in the Lower San Juan River.’ 199

The judgment is more detailed concerning the activities of Costa Rica. The Court outlined its approach as follows:

… the Court will make its own determination of the facts, on the basis of the totality of the evidence presented to it, and it will then apply the relevant rules of international law to those facts which it has found to be established. 200

Specifically, the Court began its inquiry by first considering whether, on the basis of the evidence before it, Costa Rica had caused significant transboundary harm to Nicaragua by constructing the road along the San Juan River. From this finding, the Court then considered whether Costa Rica had breached its substantive obligations under customary international law, including whether Costa Rica had breached its obligation ‘not to cause’ significant transboundary harm.

In order to determine whether Costa Rica's activities had caused harm to Nicaragua, the ICJ considered if construction of the road had increased the amount of sediment in the river. It concluded that ‘the amount of sediment in the river due to the construction of the road represents at most two per cent of the river's total load’. 201 It then considered whether this sediment had caused significant harm. The Court noted that the river ‘naturally carries a heavy sediment load’ and that the volume of sediment from the construction of the road was therefore ‘insignificant’ compared to the river's total sediment load. 202 Drawing on the understanding of ‘significant’ in the ILC Draft Articles, Nicaragua had argued that provided the change in sediment load was measurable, this was sufficient to qualify as significant transboundary harm. 203 However, the Court dismissed this argument in the given circumstances. It held that:

Sediment is naturally present in the river in large quantities, and Nicaragua has not shown that the river's sediment levels are such that additional sediment eroded from the road passes a sort of critical level in terms of its detrimental effects. Moreover, the Court finds that, contrary to Nicaragua's submissions, the present case does not concern a situation where sediment contributed by the road exceeds maximum allowable limits, which have not been determined for the San Juan River. 204

The Court further held that, given the high natural variability of the river's sediment load, the relative impact of sediment from construction of the road was low. 205 As such, the increase in sediment alone did not constitute significant transboundary harm. 206

The Court then considered whether the two per cent increase in sediment was causing significant transboundary harm to the river's morphology, navigability, and to Nicaragua's dredging programme. 207 The Court stated that it was uncertain as to whether the sediment from the road had caused further impacts on the river. 208 There were other factors that might have caused this, independent of Costa Rica's activities. 209 In other words, the ‘chain of causation’ could not be established that linked the sediment from Costa Rica's road to the harm claimed by Nicaragua. Moreover, the Court was not convinced that a two per cent increase in sediment would significantly affect Nicaragua's dredging burden. 210 Nicaragua had not established this claim, nor had it established the claim that the river's morphology or ecosystem had been significantly altered. 211 Claims that the road had negatively affected communities living along the river were also unsubstantiated. 212 The Court therefore concluded that, as none of Nicaragua's claims of transboundary harm had been established, Costa Rica had not ‘breached its substantive obligations under customary international law concerning transboundary harm’. 213

3.3 Implications of the Certain Activities case for the no-harm rule

3.3.1 Increased understanding of procedural obligations

The Certain Activities case clarifies the sequence in which states must fulfil procedural obligations flowing from the no-harm rule. It suggests that procedural obligations flow progressively on from each other. Each progression is contingent on a finding that there is a risk of significant transboundary harm. The judgment further affirms that, if the duty to conduct an EIA arises, states must conduct an EIA prior to the commencement of an activity. Brunnée suggests that in this respect, the judgment in the Certain Activities case may bolster the preventative function of the no-harm rule by ‘clarifying the circumstances in which related procedural obligations are triggered.’ 214 This article agrees in so far as the timing of procedural obligations is concerning.

However, further clarification of the threshold level of ‘significant’ harm is needed to better understand the circumstances within which these procedural obligations will arise. Determining whether an activity poses a risk of significant transboundary harm is typically done by states on a case-by-case basis. 215 The Court's approach in the Certain Activities case suggests that greater guidance is needed on how this threshold is to be determined. The ICJ appears to have set a high standard for what it considers to be ‘significant’ transboundary harm. For example, in the context of the San Juan River, the Court did not consider a two per cent increase in sediment levels to meet the threshold level of ‘significant’ harm. Its decision implies that, in the context of this case, the increase in sediment needed to be more than merely detectable in order to qualify as significant transboundary harm. This matches the interpretation of ‘significant’ harm promoted by the ILC in its Draft Articles: that significant harm is ‘something more than “detectable” but need not be at the level of “serious” or “substantial”.’ 216 However, it remains unclear as to when harm would be considered ‘more than detectable’ in these circumstances.

In its decision, the Court highlighted factors that contributed to its determination of a risk of significant transboundary harm from Costa Rica's construction of a road. These included the likelihood of natural disasters and the proximity of Ramsar protected wetlands. However, as pointed out by Judge Ad Hoc Dugard in his separate opinion, the Court appears to have placed different weight on the proximity of Ramsar protected wetlands in both cases. The determination of significant transboundary harm therefore appears to be a complex decision based on a number of competing factors. Greater transparency as to the Court's determination of relevant factors and weighting attributed to them in future cases might provide states with greater guidance as to how to determine this threshold, and therefore the circumstances in which procedural obligations are likely to arise.

In the Certain Activities case, the Court also affirmed a new procedural obligation. Prior to commencing an activity, states must first ascertain whether a proposed activity poses a risk of significant transboundary harm. This obligation may be satisfied by conducting a preliminary risk assessment. If the result of this assessment is affirmative, this gives rise to the obligation to conduct a full environmental impact assessment. This procedural obligation has implications for foreseeability of risk. The judgment affirms that states must take positive steps to inform themselves as to whether an activity poses a risk of significant transboundary harm.

However, whether this obligation will have a practical influence on the prevention of significant transboundary harm and harm to the global commons is yet to be seen. It arguably suffers from the same limitations as the duty to conduct an EIA. Namely, the standard and extent to which states must assess risk of transboundary harm and harm to the global commons is not spelt out under customary international law. 217 Clearer standards may similarly be needed to enhance the effectiveness of this procedural obligation. This obligation is now the gatekeeper for the obligations to conduct an EIA and notify and consult with other states. If it were to be conducted carelessly or in a perfunctory manner, risks of transboundary harm might not be identified, and states may not fulfil other procedural obligations designed to prevent significant transboundary harm.

3.3.2 Increased ambiguity concerning the substantive obligation

Whereas the decision in the Certain Activities case can be seen to enhance existing understandings of procedural obligations to a certain extent, it muddies the water when it comes to the substantive obligation under the no-harm rule. As demonstrated in section 2, legal scholars have generally interpreted the no-harm rule as providing states with a substantive obligation of due-diligence. In his Third Report as Special Rapporteur for the ILC's new project on the protection of the atmosphere, Murase notes that:

[a] State may be deemed to have failed in its duty of due diligence only if it knew or ought to have known that the particular activities would cause significant harm to another State. 218

In other words, the duty of due diligence is triggered by foreseeability of risk, and does not presume that actual harm has been caused. 219 According to Boyle, establishing that transboundary harm has actually resulted from an activity does not indicate whether a state has failed to act diligently. 220 Redgwell further suggests that breach of the duty of due diligence is determined by whether a state has failed to ‘apply the restraints on transboundary injurious activities that it may reasonably be expected to adopt’ in the given circumstances. 221 The prevailing opinion of legal scholars is therefore that breach depends on conduct, and not on proof of actual harm. 222

However, the way in which the Court addressed the substantive duty in the Certain Activities case suggests that the standard of care is not so clear cut. In considering the substantive obligations of Costa Rica and Nicaragua, the Court only considered whether significant transboundary harm had resulted from Costa Rica and Nicaragua's activities. Aside from its analysis of procedural obligations, the judgment does not consider whether the conduct of either party met the required standard of due diligence in the given circumstances. For example, the Court did not examine whether Nicaragua or Costa Rica had adopted and/or vigilantly enforced appropriate rules and measure, or whether they should have taken a precautionary approach. This is especially puzzling in light of the fact that the Court had already determined that Costa Rica's road project presented a risk of significant transboundary harm and, hence, triggered the duty to conduct an EIA. 223 Contemporary state practice does not support a duty of result for transboundary harm. 224 Yet, the Court's approach in the Certain Activities case suggests that the result of an activity nevertheless has some bearing on whether the substantive obligation under the no-harm rule has been breached. The Court's decision therefore appears to conflict with previous understandings of the substantive obligation under the no-harm rule and what is required to establish a breach.

The decision in the Certain Activities case also raises questions concerning the relationship between procedural obligations and the substantive obligation under the no-harm rule. 225 As noted above, the decision of the ICJ in the Pulp Mills case suggests that procedural obligations are an integral part of a state's due diligence obligation. In this view, failure to satisfy a procedural obligation (such as the duty to conduct an EIA) can also amount to a breach of due diligence. However, as noted by Brunnée, the decision in the Certain Activities case does not fit this interpretation. 226 The Court does not explicitly state if Costa Rica's failure to conduct an EIA prior to the construction of the road also breached its substantive obligation to prevent harm. It appears to suggest that procedural obligations and the substantive obligation are entirely separate. 227

Brunnée summarises the overall approach of the ICJ to the no-harm rule as follows:

… it appears as if the ICJ distinguishes between the duty to take diligent steps to prevent significant transboundary harm, which it then deals with under the rubric of separate procedural obligations, and the duty to take diligent steps not to cause harm, which it considers cannot be violated simply by a failure to act diligently. 228

If this interpretation of the no-harm rule is correct, it could have significant implications for the capacity of the rule to respond to contemporary environmental issues. Until such time as harm may materialise, states would have limited recourse under the no-harm rule if another state fails to take adequate measures to prevent a risky activity under its jurisdiction or control from causing significant transboundary harm (ie enact relevant domestic law rules and/or enforce them). It may still be possible to hold the source state to account for not conducting an EIA or for failing to notify and consult with potentially affected states. But it would only be possible to invoke the substantive obligation once harm has been caused. This would arguably limit the capacity of the no-harm rule to play a preventative role in international environmental law, especially with regards to issues such as climate change and geoengineering for which it will be challenging to establish causation and attribution of harm. 229

The ICJ's decision regarding the substantive obligation under the no-harm rule does not appear to advance existing understandings. It does not fit with the prevailing interpretations and expectations of the ILC and legal scholars. The decision also raises more questions than it answers concerning the duty of due diligence, the relationship between harm and breach, and the relationship between the procedural and the substantive obligations to prevent harm. However, there may nevertheless turn out to be a silver lining. The ambiguity in this Court's judgment has already caused one prominent international law scholar to reconsider the substantive obligation under the no-harm rule and question existing interpretations that may have been taken for granted. 230 It will be interesting to see whether the Certain Activities case will prompt other legal scholars to do likewise.

4 CONCLUSION

The no-harm rule has continued to develop since it was first recognised by the Tribunal in the Trail Smelter arbitration. The analysis in this article identifies three phases in the no-harm rule's development. In the first phase, the no-harm rule was largely a reactive rule. It responded to harm after it had been caused and most likely provided states with a duty of result. Its primary focus was to protect and balance the rights of states. In the second phase, the no-harm rule was characterised as providing states with a positive duty to prevent harm, and was extended to also include harm to the global commons. In the third and most recent phase, the no-harm rule has been interpreted as providing states with a duty of due diligence to prevent significant transboundary harm and harm to the global commons. During this phase, procedural obligations developed that were seen to also be connected to the duty of due diligence.

The Certain Activities case further clarifies how states are to satisfy procedural obligations by specifying the order within which they arise. The Certain Activities case also enhances the preventative capacity of the no-harm rule by requiring states to actively inform themselves as to whether an activity initially poses a risk of significant transboundary harm. However, the decision does not appear to advance existing understandings of the substantive obligation under the no-harm rule. The Court did not consider the duty of due diligence. Its approach raises significant questions concerning the standard of care under the substantive obligation, including the relationship between breach and actual harm, and the relationship between breach and the procedural obligations. It is hoped that the decision in the Certain Activities case might nevertheless encourage states, international courts and tribunals and legal scholars to examine the no-harm rule afresh, and consider how it might be further developed better to respond to contemporary threats of harm to the global environment.

  • 1

    Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) and Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (Judgment) (International Court of Justice, General List No 150 and 152, 16 December 2015) <http://www.icj-cij.org/docket/files/152/18848.pdf> accessed 28 January 2016 (‘Certain Activities’).

  • 2

    Trail Smelter (United States v Canada) (Awards) (1938 and 1941) 3 RIAA 1905 (‘Trail Smelter (Awards)’).

  • 3

    See

    Verheyen Roda , Climate Change Damage and International Law: Prevention Duties and State Responsibility , ( Koninklijke Brill NV , Leiden 2005 ) 149 - 50 .

    Sands Philippe & Peel Jacqueline , Principles of International Environmental Law , ( CUP , Cambridge 2012 ) 197 .

  • 4

    See, eg, Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226, [29] (‘Nuclear Weapons Advisory Opinion’); Gabčíkovo/Nagymaros Project (Hungary v Slovakia) (Judgment) [1997] ICJ Rep 7, [53] (‘Gabčíkovo/Nagymaros Project’).

  • 5

    See, eg, Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, opened for signature 29 December 1972, 1046 UNTS 138 (entered into force 30 August 1975) preamble (‘London Convention’); Convention on Biological Diversity, opened for signature 5 June 1992, 1760 UNTS 79 (entered into force 29 December 1993) art 3 (‘CBD’); United Nations Framework Convention on Climate Change, opened for signature 9 May 1992, 1771 UNTS 107 (entered into force 21 March 1994) preamble (‘UNFCCC’); Convention on Long-range Transboundary Air Pollution, opened for signature 13 November 1979, 1302 UNTA 217 (entered into force 16 March 1983) preamble (‘LRTAP’); Vienna Convention for the Protection of the Ozone Layer, opened for signature 22 March 1985, 1513 UNTS 293 (entered into force 22 September 1988) preamble (‘Ozone Convention’); United Nations Convention on the Law of the Sea, opened for signature 10 December 1982, 1833 UNTS 3 (entered into force 16 November 1994) arts 192–194(2) (‘UNCLOS’).

  • 6

    Benoît Mayer, ‘The relevance of the no-harm principle to climate change law and politics’ (2016) 19 Asia Pacific Journal of Environmental Law 79, 81. See also Verheyen (n 3) 147.

  • 7

    See, eg

    Peel Jacqueline , ' ‘Unpacking the elements of a state responsibility claim for transboundary pollution’ ', in S Jayakumar, Tommy Koh, Robert Beckman & Hao Duy Phan (eds), Transboundary Pollution: Evolving Issues of International Law and Policy , ( Edward Elgar , Cheltenham UK and Northampton MA 2015 ) 51 .

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    Alan Boyle, ‘Transboundary air pollution: a tale of two paradigms’ in Jayakumar et al (eds), ibid, at 233.

  • 8

    See, eg, Peel (n 7); Christoph Schwarte and Will Frank, ‘The International Law Association's Legal Principles on Climate Change and Climate Liability Under Public International Law’ (2014) 4(3–4) Climate Law 201; Benoît Mayer, ‘The Applicability of the Principle of Prevention to Climate Change: A Response to Zahar’ (2015) 5(1) Climate Law 1. The International Law Association considered the relevance of the no-harm rule to climate change in its Declaration on the Legal Principles Related to Climate Change. See International Law Association, Resolution 2/2014: Declaration of Legal Principles Relating to Climate Change (7–11 April 2014) International Law Association <http://www.ila-hq.org/en/committees/index.cfm/cid/1029> art 7. The no-harm rule is also being considered by the International Law Commission (ILC) in its new project on the protection of the atmosphere. See Shinya Murase, ‘Third report on the protection of the atmosphere’, Protection of the Atmosphere, International Law Commission, 68th sess, UN Doc A/CN.4/692 (2 May–10 June and 4 July–12 August 2016), 6–33.

  • 9

    See Kerryn Brent, Jeffrey McGee and Amy Maguire, ‘Does the “No-Harm” Rule Have a Role in Preventing Transboundary Harm and Harm to the Global Atmospheric Commons from Geoengineering?’ (2015) 5(1) Climate Law 35. See also David Reichwein et al, ‘State Responsibility for Environmental Harm from Climate Engineering’ (2015) 5(2–4) Climate Law 142; Barbara Saxler, Jule Siegfried and Alexander Proelss, ‘International liability for transboundary damage arising from stratospheric aerosol injections’ (2015) 7(1) Law, Innovation and Technology 112.

  • 10

    The Royal Society, ‘Geoengineering the climate: science, governance and uncertainty’ (The Royal Society, London 2009) 1. The term ‘geoengineering’ encompasses proposals to draw carbon dioxide directly from the atmosphere and proposals to reduce global mean surface temperatures by reducing the amount of solar radiation that warms the Earth. A prominent proposal to draw carbon dioxide from the atmosphere is to fertilize the ocean with iron to stimulate large algal blooms (at 16). A prominent proposal to increase the amount of sunlight reflected away from the Earth is to create a fine layer of reflective aerosols in the stratosphere (at 29).

  • 11

    The exception to this is ocean fertilisation geoengineering, which is addressed under an amendment to the 1996 Protocol to the 1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, opened for signature 7 November 1996, [2006] ATS 11 (entered into force 24 March 2006). See Resolution LP.4(8): On the Amendment to the London Protocol to Regulate the Placement of Matter for Ocean Fertilization and other Marine Geoengineering Activities, LC 35/15 (adopted 18 October 2013).

  • 12

    Johnson Toribiong, ‘Statement by the Honorable Johnson Toribiong, President of the Republic of Palau to the 66th Regular Session of the United Nations General Assembly’ (Speech delivered at the 66th Regular Session of the United Nations General Assembly, New York, 22 September 2011) <https://gadebate.un.org/sites/default/files/gastatements/66/PW_en.pdf>. See also Stuart Beck and Elizabeth Burleson, ‘Inside the System, Outside the Box: Palau's Pursuit of Climate Justice and Security at the United Nations’ (2014) 3(1) Transnational Environmental Law 17, 24–8.

  • 13

    See Beck and Burleson (n 12) 26. According to Beck and Burleson, over 30 countries supported the initiative, but greater support was needed for the UN General Assembly to refer the issue to the ICJ for an advisory opinion.

  • 14

    Birnie Patricia , Boyle Alan & Redgwell Catherine , International Law and the Environment , ( OUP , Oxford 2009 ) 140 .

    See also

    Lammers J G , Pollution of International Watercourses: A Search for Substantive Rules and Principles of Law , ( Martinus Nijhoff , Leiden 1984 ) 504 .

    Lammers similarly notes that they are often invoked by states ‘as evidence of what the rules and principles of international law are on a given point’.

  • 15

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015).

  • 16

    Certain Activities Carried out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (Order of 17 April 2013) [2013] ICJ Rep 166; Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (Order of 17 April 2013) [2013] ICJ Rep 184.

  • 17

    See also Catherine Redgwell, ‘Transboundary pollution: principles, policy and practice’ in Jayakumar et al (eds) (n 7) 11. Redgewell makes this comment in light of the Aerial Herbicide Spraying case that was settled before the ICJ rendered judgment on the merits. See Aerial Herbicide Spraying (Ecuador v Colombia) (Order of 13 September 2013) [2013] ICJ Rep 278 (‘Aerial Herbicide Spraying’).

  • 18

    Birnie, Boyle and Redgwell (n 14) 140.

  • 19

    Browlie Ian , ' ‘State Responsibility and International Pollution: A Practical Perspective’ ', in Daniel Barstow Magraw (ed), International Law and Pollution , ( University of Pennsylvania Press , Philadelphia 1991 ) 120 - 121 .

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  • 20

    Establishing and interpreting the content of customary international law can be distinguished from analysing the formation of customary international law through state practice and opinio juris. This article follows the approach of Brownlie, who suggests that it is simply a question of ‘what material should we be looking at’ to understand the content of customary international law, and not a question of the ‘doctrine of the formation of rules of customary international law.’ Brownlie (n 19) 121.

  • 21

    For the sake of brevity, analysis in this article is restricted to prominent disputes before international courts and tribunals, key international declarations, and the work of the ILC. It is acknowledged that there are useful sources beyond this scope, including examples of state practice on transboundary harm such as the Fukuryu Maru incidence between Japan and the United States (see Brownlie (n 19) 121–2) and the issue of transboundary haze pollution from forest fires in Indonesia (see Allen L Springer, Cases of Conflict: Transboundary Disputes and the Development of International Environmental Law (University of Toronto Press, Ontario 2016) 54–83). However, engagement with these sources is beyond the scope of this article.

  • 22

    Trail Smelter (Awards) (1938 and 1941) 3 RIAA 1905; The contribution of the Trail Smelter arbitration to the development of the no-harm rule has also been considered in Brent, McGee and Maguire (n 9) 40–1.

  • 23

    Trail Smelter (Awards) (1938 and 1941) 3 RIAA, 1917, 1923–4.

  • 24

    Ibid, 1905, 1917, 1920. The United States claimed damages in respect of: cleared land and improvements thereon; uncleared land and improvements thereon; livestock; urban property; and business enterprises.

  • 25

    Convention for Settlement of Difficulties Arising from Operation of Smelter at Trail BC, United States-Canada, opened for signature 15 April 1935, 893 US Treaty Series (entered into force 3 August 1935). See also Springer (n 21) 25.

  • 26

    Ibid, art III(2).

  • 27

    Trail Smelter (Awards) (1938 and 1941) 3 RIAA 1905, 1965 (emphasis added).

  • 28

    See eg

    McCaffrey Stephen C , ' ‘Of Paradoxes, Precedents, and Progeny: The Trail Smelter Arbitration 65 Years Later’ ', in Rebecca M Bratspies & Russell A Miller (eds), Transboundary Harm in International Law: Lessons from the Trail Smelter Arbitration , ( CUP , Cambridge 2006 ) 34 - 36 .

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    Alfred P Rubin, ‘Pollution by Analogy: The Trail Smelter Arbitration [Abridged]’ in Bratspies and Miller (eds), ibid 46, 48–51.

  • 29

    Convention for Settlement of Difficulties Arising from Operation of Smelter at Trail BC, United States-Canada, opened for signature 15 April 1935, 893 US Treaty Series (entered into force 3 August 1935) art IV; Trail Smelter (Awards) (1938 and 1941) 3 RIAA 1905, 1908; Springer (n 21) 25–6.

  • 30

    Okowa Phoebe , State Responsibility for Transboundary Air Pollution in International Law , ( OUP , Oxford 2000 ) 67 .

    See also

    Stephens Timothy , International courts and environmental protection , ( CUP , Cambridge, UK and New York 2009 ) 124 - 5 Cambridge Studies in International and Comparative Law .

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  • 31

    See, eg, Redgwell (n 17) 11; Boyle (n 7) 233; Springer (n 21) 24.

  • 32

    See McCaffrey (n 28) 39; Brent, McGee and Maguire (n 9) 41.

  • 33

    Trail Smelter (Awards) (1938 and 1941) 3 RIAA 1905, 1966.

  • 34

    See, eg, Stephens (n 30) 133; Pierre-Marie Dupuy and Cristina Hoss, ‘Trail Smelter and Terrorism: International Mechanisms to Combat Transboundary Harm’ in Bratspies and Miller (eds) (n 28) 225, 227–30.

  • 35

    See ‘Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, with Commentaries’ (2001) II(2) Yearbook of the International Law Commission 149 (‘Draft Articles on Prevention’) 148. The Draft Articles refer the Trail Smelter arbitration as supporting the ‘principle of prevention’, which provides a duty of due diligence.

  • 36

    Trail Smelter (Awards) (1938 and 1941) 3 RIAA 1905, 1980.

  • 37

    LFE Goldie, ‘Liability for Damage and the Progressive Development of International Law’ (1965) 14(4) The International and Comparative Law Quarterly 1189, 1230. See also Springer (n 21) 26.

  • 38

    Sands and Peel (n 3) 712.

  • 39

    See Brent, McGee and Maguire (n 9) 41.

  • 40

    The Corfu Chanel Case (United Kingdom v Albania) (Merits) [1949] ICJ Rep 4.

  • 41

    Ibid, 22.

  • 42

    See, eg, Okowa (n 30) 68; Birnie, Boyle and Redgwell (n 14) 144;

    Nanda Ved P & Pring George (Rock) , International Environmental Law and Policy for the 21st Century , ( Martinus Nijhoff Publishers , Leiden 2013 ) 82 .

    Triggs Gillian D , International Law: Contemporary Principles and Practices , ( LexisNexis , London 2006 ) 790 .

  • 43

    See also Birnie, Boyle and Redgwell (n 14) 144. They note that the ICJ failed to clarify what the rights of states are, especially with respect to the environment. For further critique, see Lammers (n 14) 526; Stephens, (n 30) 123.

  • 44

    Lake Lanoux Arbitration (France v Spain) (1957) 24 ILR 101. See Stephens (n 30) 169.

  • 45

    Lake Lanoux Arbitration (1957) 24 ILR 101.

  • 46

    Ibid, 109–10.

  • 47

    The agreement was the 1866 Treaty of Bayonne and Additional Act. These agreements delineated the boundary between France and Spain in the Pyrénées area and also established shared water rights between the states. The relevant sections are set out in the Lake Lanoux Arbitration (1957) 24 ILR 101, 102–05.

  • 48

    Lake Lanoux Arbitration (1957) 24 ILR 101, 112–14.

  • 49

    Ibid, 123–5.

  • 50

    Ibid, 129.

  • 51

    See, eg, Sands and Peel (n 3) 197; Stephens (n 30) 171; Reichwein et al (n 9) 152 nn 46.

  • 52

    See also, Stephens (n 30) 169. According to Stephens, the Tribunal only considered the impact of the French proposal on the utilisation of the River Carol for human purposes, and ignored potential ecological impacts. He notes that the decision focused on ‘ensuring the return of an equivalent amount of water to the watercourse, not how that return was effected and certainly not whether an upstream project would result in the permanent alteration of the watercourse environment.’

  • 53

    The growing concern for the environment can be seen in the impact had by publications such as:

    Carson Rachel , Silent Spring , ( Hamish Hamilton , London 1963 ).

    and Garrett Hardin, ‘The Tragedy of the Commons’ (1968) 162(3859) Science 1243.

  • 54

    Declaration of the United Nations Conference on the Human Environment, UN Doc.A/CONF/48/14/REV.1 (16 June 1972) (‘Stockholm Declaration’).

  • 55

    States never intended the Stockholm Declaration itself to be a legally binding treaty. From the outset, it was decided within the conference Preparatory Committee that the Declaration would create a set of soft-law principles to guide the development of global environmental policy. See Report of the Preparatory Committee for the United Nations Conference on the Human Environment, Preparatory Committee for the United Nations Conference on the Human Environment, Second Session, (8–19 February 1971) A/Conf.48/PC49, 16.

  • 56

    See, eg, Sands and Peel (n 3) 195–6; Ulrich Beyerlin and Thilo Marauhn, International Environmental Law (Hart, Oxford 2011) 39.

  • 57

    See, eg, Birnie, Boyle and Redgwell (n 14) 145; Sands and Peel (n 3) 32. Brent, McGee and Maguire (n 9) 42.

  • 58

    It is unclear whether this development was widely accepted by states as a part of customary international law at the time the Stockholm Declaration was negotiated. Following the conference, Canada declared that ‘Principle 21 in fact accorded with existing international law’. See Report of the United Nations Conference on the Human Environment, 5–16 June 1972, United Nations Publication, A/CONF.48/14/Rev, 64. This suggests that at least one state accepted this wording as representing customary international law. It is clear that by the time of the Rio Conference in 1992, the no-harm rule as formulated by Principle 21 was accepted by states as representing customary international law. See United Nations Conference on Environment and Development, GA Res 228, 2nd Comm, 44th sess, 85th mtg, UN Doc A/RES/44/228.

  • 59

    Sands and Peel (n 3) 32; Louis B Sohn, ‘The Stockholm Declaration on the Human Environment’ (1973) 14(3) Harvard International Law Journal 423, 493.

  • 60

    Sohn, ibid, 493.

  • 61

    Brent, McGee and Maguire (n 9) 42. See also Birnie, Boyle and Redgwell (n 14) 147.

  • 62

    Declaration of the United Nations Conference on Environment and Development, UN Doc.A/CONF.151/26/Rev.1 (3–14 June 1992) (‘Rio Declaration’) The wording of Principle 2 of the Rio Declaration is the same as Principle 21 of the Stockholm Declaration, with the exception that it refers to the environmental and developmental policies of states. This change reflects the concept of sustainable development which is emphasised throughout the Rio Declaration. See Donald R Rothwell et al, International Law: Cases and Materials with Australian Perspectives (CUP, Cambridge 2011) 561.

  • 63

    Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226, [29].

  • 64

    See Stephens (n 30) 153.

  • 65

    Nuclear Tests Case (Australia v France) (Judgment) [1974] ICJ Reports 253; Nuclear Tests Case (New Zealand v France) (Judgment) [1974] ICJ Reports 457.

  • 66

    ‘Note from New Zealand Embassy to French Ministry of Foreign Affairs’, 14 March 1963 in ‘Application Instituting Proceedings Submitted by the Government of New Zealand’ Nuclear Tests Case (New Zealand v France) [1973] ICJ Pleadings 2, 14.

  • 67

    ‘Note of 3 January 1973 of the Australian Ambassador, Paris, to the French Foreign Minister’ in Application Instituting Proceedings, Nuclear Tests Case (Australia v France) [1973] ICJ Pleadings 1, 50.

  • 68

    ‘Note De L'Ambassadeur De France à Canberra, en date du 7 Février 1973, au Premier Ministre et Ministre des Affaires Éstrangères de L'Australie [Traduction]’ in Nuclear Tests Case (Australia v France) [1973] ICJ Pleadings 1, 57.

  • 69

    Ibid, 53.

  • 70

    Ibid.

  • 71

    Ibid, 55.

  • 72

    Ibid.

  • 73

    ‘Letter from New Zealand Prime Minister to French Foreign Minister, 9 March 1973’ in ‘Application Instituting Proceedings Submitted by the Government of New Zealand’ Nuclear Tests Case (New Zealand v France) [1973] ICJ Pleadings 2, 37.

  • 74

    The ICJ declined to rule on the merits of the cases as France had ceased atmospheric nuclear testing in the Pacific, and had made a unilateral declaration to that effect. See Nuclear Tests Case (Australia v France) (Judgment) [1974] ICJ Reports 253, [42]–[59]. France did not file proceedings or make any formal submission in the case, as it did not believe the ICJ to be competent to adjudicate the dispute (at 256–7).

  • 75

    The decision of the tribunal in the Corfu Channel case suggested that states have the duty to warn other states of imminent threats of harm. See Corfu Chanel [1949] ICJ Rep 4, 22. See also Nanda and Pring (n 42) 82; Birnie, Boyle and Redgwell (n 14) 144. Similarly the Tribunal in the Lake Lanoux arbitration confirmed that upstream states have a duty to notify and consult with downstream states with regards to proposed activities that are likely to cause significant transboundary harm. Lake Lanoux Arbitration (1957) 24 ILR 101, 127–8. See also Mari Koyano, ‘The Significance of Procedural Obligations in International Environmental Law: Sovereignty and International Co-operation’ (2011) 54 Japanese Yearbook of International Law 97, 102.

  • 76

    Principle 14 discourages the relocation and transfer to other states of dangerous activities or substances. Principle 15 encourages states to apply a precautionary approach when conducting risky activities, stating that ‘[w]here there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ Principle 17 asserts that states shall undertake an environmental impact assessment for all ‘proposed activities that are likely to have a significant adverse impact on the environment’. Principle 19 declares that for such activities, states must also notify and consult with other potentially affected states.

  • 77

    See Birnie, Boyle and Redgwell (n 14) 138. According to Birnie Boyle and Redgwell, the inclusion of procedural obligations in the Rio Declaration reflected contemporary developments in international law and state practice concerning transboundary harm. They state that the Rio Declaration therefore provided a ‘strong starting point for the further elaboration of this part of international environmental law by the International Court of Justice and the International Law Commission.’

  • 78

    Legality of the use by a State of Nuclear Weapons in Armed Conflict (Advisory Opinion) [1996] ICJ Rep 66, 140–42 (Judge Weeramantry). According to Judge Weeramantry ‘… any State action which damages the environment in the way that nuclear weapons do is a violation of the obligation of environmental protection which modern international law places upon States. A contrary view would negative the basic logic of environmental law and send a tremor through the foundations of this vital subdiscipline of modern international law.’ Judge Weeramantry states that his comments on the obligations of states with regards to the environment in this dissenting opinion were supplementary to his dissenting opinion in Nuclear Weapons (advisory opinion) [1996] ICJ Rep 226, 506 (Judge Weeramantry).

  • 79

    Nuclear Weapons (advisory opinion) [1996] ICJ Rep 226, 578 (Judge Koroma). Koroma argued that, when considering the legality of the use of nuclear weapons in the context of international environmental law, the relevant issue was not whether the no-harm rule would deny a state the right to self-defence, but the impact they have on the environment. In his opinion, the majority should consider the radioactive effects of nuclear weapons, and their widespread contamination of the natural and human environment. His argument implies that the use of nuclear weapons would likely breach the no-harm rule for this reason.

  • 80

    Draft Articles on Prevention (n 35).

  • 81

    In 1974, the ILC decided to embark on a project to codify, clarify and progressively develop International liability for injurious consequences arising out of acts not prohibited by international law. See ‘Report of the International Law Commission on the work of its twenty-sixth session (6 May-26 July 1974)’ (1974) II(1) Yearbook of the International Law Commission, 305 [163]. The original aim of this project was to spell out the content of the duty to prevent transboundary harm and establish rules of liability for transboundary harm once it has been caused. For an overview of the initial nature and scope of the project, see ‘Preliminary report on international liability for injurious consequences arising out of acts not prohibited by international law, by Mr Robert Q Quentin-Baxter, Special Rapporteur’ (1980) II(1) Yearbook of the International Law Commission 247, 262–6. In 1997, the ILC decided to split the topic in two, separating prevention of harm from liability. See ‘International Liability for Injurious Consequences Arising out of Acts not Prohibited by International Law, Report of the Working Group’ International Law Commission, (12 May–18 July 1997) 49 sess A/CN.4/L/536 1997, 2 [3]. This decision resulted in two draft documents: the 2001 Draft Articles on Prevention and the 2006 ‘Draft principles on the allocation of loss in the case of transboundary harm arising out of hazardous activities’, (2006) II(2) Yearbook of the International Law Commission 59. The Draft Principles on Loss address the issue of liability for private (ie non-state) actors for transboundary harm.

  • 82

    Evidence of this grounding can be seen in the Commentaries to the Draft Articles on Prevention (n 35) that refer extensively to such sources.

  • 83

    International Law Commission, Membership (20 July 2015) International Law Commission <http://legal.un.org/ilc/ilcmembe.shtml#a5>.

  • 84

    Fernando Lusa Bordin, ‘Reflections of Customary International Law: The Authority of Codification Conventions and ILC Draft Articles in International Law’ (2014) 63(3) International and Comparative Law Quarterly 535, 537.

  • 85

    See International Law Commissions, About the Commission: Organization, programme and methods of work- Methods of Work (12 January 2016) International Law Commission <http://legal.un.org/ilc/methods.shtml>.

  • 86

    See definitions of progressive development and codification in article 15 of the Statute of the International Law Commission.

  • 87

    This issue was raised by Colombia in the Arial Herbicide Spraying Case and is discussed further below. See ‘Counter Memorial of the Republic of Colombia Volume I’, Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 March 2010, 353–60.

  • 88

    See, eg, ‘Memorial of Ecuador’ Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 April 2009, 273, 278–80, 282, 286–7; ‘Memorial of Costa Rica Volume I’ Certain Activities Carried out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List no 150, 5 December 2011) <http://www.icj-cij.org/docket/files/150/18512.pdf> accessed on 18 February 2016, [5.6]; ‘Memorial of Nicaragua Volume I’ Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (International Court of Justice, General List no 152, 19 December 2012), http://www.icj-cij.org/docket/files/152/18514.pdf> accessed on 19 February 2016, 142, 144, 146, 174.

  • 89

    See, eg, Responsibilities and Obligations of States Sponsoring Persons and Entities with Respect to Activities in the Area (Advisory Opinion), [2011] ITLOS Reports 10, [116] (‘Activities in the Area’).

  • 90

    See, eg, Peel (n 7) 67; Alan Boyle, ‘Transboundary air pollution: a tale of two paradigms’ in Jayakumar et al (eds) (n 7) 233, 237; Reichwein et al (n 9) 155.

  • 91

    Dupuy and Hoss (n 34) 230.

  • 92

    See Birnie, Boyle and Redgwell (n 14) 141. They describe the Draft Articles on Prevention as an ‘authoritative exposition of the existing law’. See also Verheyen (n 3) 154; Redgwell (n 17) 15.

  • 93

    Draft Articles on the Prevention (n 35) 148.

  • 94

    Ibid, 153.

  • 95

    Boyle (n 7) 237.

  • 96

    Draft Articles on the Prevention (n 35) 149 art 1, 151–2.

  • 97

    Draft Articles on the Prevention (n 35) 149 art 1. ‘Significant’ is defined as ‘something more than “detectable” but need not be at the level of “serious” or “substantial”’ (at 152).

  • 98

    Ibid, 151–2.

  • 99

    Early in the drafting process, the ILC considered including harm to the global commons. In 1990, Special Rapporteur Barboza advocated including harm to the global commons within the draft articles under the ILCs mandate of progressive development. See ‘Sixth report on international liability for injurious consequences arising out of acts not prohibited by international law, by Mr Julio Barboza, Special Rapporteur’ (1990) II(1) Yearbook of the International Law Commission 83, 101 [72], [74]. However, consensus could not be reached within the ILC regarding the inclusion of harm to the global commons, and it was therefore not included in the Draft Articles on Prevention. See ‘First report on prevention of transboundary damage from hazardous activities, by Mr Pemmaraju Sreenivasa Rao, Special Rapporteur Rao’ (1998) International Law Commission A/CN.4/487 and Add.1, 198 [107]–[109].

  • 100

    Due diligence obligations had become prevalent in international environmental agreements. See, eg, United Nations Convention on the Law of the Sea, opened for signature 10 December 1982, 1833 UNTS 3 (entered into force 16 November 1994) (‘UNCLOS’) art 194; Vienna Convention for the Protection of the Ozone Layer, opened for signature 22 March 1985, 1513 UNTS 293 (entered into force 22 September 1988) art 2.

  • 101

    Draft Articles on Prevention (n 35) 153.

  • 102

    Ibid, 154.

  • 103

    Ibid, 155.

  • 104

    Ibid, 154.

  • 105

    Ibid.

  • 106

    Ibid, 153 and 154. This is also enacted under art 5.

  • 107

    Ibid, 154.

  • 108

    See Boyle (n 7) 237.

  • 109

    See Draft Articles on Prevention (n 35) 153.

  • 110

    Ibid, art 4.

  • 111

    Ibid, art 7.

  • 112

    Ibid, art 8.

  • 113

    Ibid, art 9.

  • 114

    See, eg, United Nations Convention on the Law of the Sea, opened for signature 10 December 1982, 1833 UNTS 3 (entered into force 16 November 1994) (‘UNCLOS’) art 194; Vienna Convention for the Protection of the Ozone Layer, opened for signature 22 March 1985, 1513 UNTS 293 (entered into force 22 September 1988) art 2.

  • 115

    Pulp Mills [2010] ICJ Rep 14, 56 [101].

  • 116

    Ibid, 79.

  • 117

    Ibid, [204].

  • 118

    Responsibilities and obligations of States with respect to activities in the Area (Advisory Opinion) (International Tribunal for the Law of the Sea, Case No 17, 1 February 2011) (‘Activities in the area’).

  • 119

    Ibid, [117].

  • 120

    Ibid, [125]–[135].

  • 121

    Aerial Herbicide Spraying (Ecuador v Colombia) (Order of 13 September 2013) [2013] ICJ Rep 278 (‘Aerial Herbicide Spraying’).

  • 122

    ‘Application Instituting Proceedings’, Aerial Herbicide Spraying (Ecuador v Colombia), International Court of Justice, General List No 138, 31 March 2008, <http://www.icj-cij.org/docket/files/138/14474.pdf> accessed 31 March 2015, 4.

  • 123

    Ibid.

  • 124

    Ibid.

  • 125

    ‘Memorial of Ecuador Volume 1’ Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 April 2009 <http://www.icj-cij.org/docket/files/138/17540.pdf> accessed 31 March 2015 [8.6]. Ecuador cited the ILC Draft Articles in support of its interpretation of the obligation of due diligence to prevent significant transboundary harm (at [8.14]). It adopted the ILC's ‘spectrum’ definition of risk of transboundary harm (at [8.18]). Ecuador cited Draft Art 7 regarding the duty to conduct an EIA (at [8.39]).

  • 126

    ‘Counter Memorial of the Republic of Colombia Volume I’, Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 March 2010 <http://www.icj-cij.org/docket/files/138/17548.pdf> accessed on 31 March 2015, [8.20]. Colombia proceeded to refute Ecuador's arguments based on the Draft Articles, but it pointed out that it nonetheless did not consider itself to be bound by the interpretation of the no-harm rule in the ILC's Draft Articles (at 8.30).

  • 127

    Ibid, [8.21], [8.23].

  • 128

    Ibid, [8.23].

  • 129

    Ibid, [8.88]–[8.89]. Colombia's submission in its Counter-memorial pre-dates the decision of the ICJ in the Pulp Mills case, which confirmed this duty to be part of customary international law.

  • 130

    Aerial Herbicide Spraying (Ecuador v Colombia) (Order of 13 September 2013) [2013] ICJ Rep 278.

  • 131

    ‘Memorial of Ecuador Volume 1’ Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 April 2009 <http://www.icj-cij.org/docket/files/138/17540.pdf> accessed on 31 March 2015, [8.27]–[8.28].

  • 132

    Ibid, [8.27].

  • 133

    ‘Counter Memorial of the Republic of Colombia Volume I’, Arial Herbicide Spraying (Ecuador v Colombia) International Court of Justice, General List No 138, 29 March 2010, <http://www.icj-cij.org/docket/files/138/17548.pdf> accessed on 31 March 2015, [8.53]–[8.55].

  • 134

    Ibid, [8.56].

  • 135

    Treaty of Limits, Costa Rica – Nicaragua, signed 15 April 1858 (entered into force 26 April 1858). See also Award in regard to the validity of the Treaty of Limits between Costa Rica and Nicaragua of 15 July 1858 (Costa Rica v Nicaragua) (Awards) (1888) XXVIII RIAA 189; Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [59].

  • 136

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [59].

  • 137

    See Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [59]–[62].

  • 138

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [63].

  • 139

    ‘Application Instituting Proceedings’, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List No 150, 18 November 2010) <http://www.icj-cij.org/docket/files/150/16279.pdf> accessed on 28 January 2016 [4].

  • 140

    Ibid, [4].

  • 141

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [65].

  • 142

    ‘Application Instituting Proceedings’, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List No 150, 18 November 2010) <http://www.icj-cij.org/docket/files/150/16279.pdf> accessed on 28 January 2016, 4.

  • 143

    ‘Memorial of Costa Rica Volume I’ Certain Activities Carried out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List No 150, 5 December 2011) <http://www.icj-cij.org/docket/files/150/18512.pdf> accessed on 18 February 2016, [4.65].

  • 144

    Ibid, [100].

  • 145

    ‘Application Instituting Proceedings’, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List No 150, 18 November 2010) <http://www.icj-cij.org/docket/files/150/16279.pdf> accessed on 28 January 2016, [4].

  • 146

    Ibid, [4].

  • 147

    ‘Counter-Memorial of Nicaragua Volume 1’ Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) (International Court of Justice, General List No 152, 6 August 2012) <http://www.icj-cij.org/docket/files/150/18522.pdf> accessed on 22 February 2016, [1.13]–[1.15].

  • 148

    Ibid, [3.21]–[3.22], [3.26].

  • 149

    Ibid, [1.14], [3.47].

  • 150

    Ibid, [5.17].

  • 151

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [64].

  • 152

    ‘Application Instituting Proceedings’, Construction of a Road by Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (International Court of Justice, General List No 152 (22 December 2011) <http://www.icj-cij.org/docket/files/152/16917.pdf> accessed on 18 February 2016, [22]–[25].

  • 153

    Ibid, [6].

  • 154

    Ibid, [6]–[10].

  • 155

    Ibid, [10], 20.

  • 156

    ‘Memorial of Nicaragua Volume I’ Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (International Court of Justice, General List No 152, 19 December 2012), <http://www.icj-cij.org/docket/files/152/18514.pdf> accessed on 19 February 2016, [5.4].

  • 157

    Ibid, [26]–[26].

  • 158

    Ibid, [5.19].

  • 159

    Vienna Convention on the Law of Treaties, opened for signature 23 May 1969, 1155 UNTS 331 (entered into force 27 January 1980).

  • 160

    ‘Memorial of Nicaragua Volume I’ Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) (International Court of Justice, General List No 152, 19 December 2012), <http://www.icj-cij.org/docket/files/152/18514.pdf> accessed on 19 February 2016, [5.24].

  • 161

    ‘Counter Memorial of Costa Rica Volume 1’ Construction of a Road in Costa Rica Along the San Juan River (Nicaragua v Costa Rica) General List No 152 (19 December 2013) <http://www.icj-cij.org/docket/files/152/18520.pdf> accessed on 22 February 2016, [5.15].

  • 162

    Ibid, [5.10]–[5.12], [5.20].

  • 163

    Ibid, [5.25], [5.41].

  • 164

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [104].

  • 165

    Ibid.

  • 166

    Ibid, [154].

  • 167

    Ibid, [104].

  • 168

    Ibid, [104].

  • 169

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [105].

  • 170

    Ibid.

  • 171

    Ibid.

  • 172

    Ibid.

  • 173

    Ibid, [107].

  • 174

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [108].

  • 175

    Ibid, [155].

  • 176

    Ibid.

  • 177

    Ibid.

  • 178

    Convention on Wetlands of International Importance, opened for signature 2 February 1971, 996 UNTS 246 (entered into force 21 December 1975).

  • 179

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [155].

  • 180

    Ibid, [156].

  • 181

    Ibid.

  • 182

    Ibid, [154].

  • 183

    Ibid, [157].

  • 184

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [157].

  • 185

    Ibid, [158].

  • 186

    Ibid.

  • 187

    Ibid, [159].

  • 188

    Ibid, [160]–[161].

  • 189

    Ibid, [161].

  • 190

    Ibid.

  • 191

    Ibid, [162].

  • 192

    Ibid, [168].

  • 193

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), (Judge Ad Hoc Dugard) [20]–[35].

  • 194

    Ibid, [35].

  • 195

    Ibid, [32].

  • 196

    Ibid, [35].

  • 197

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [118].

  • 198

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [119].

  • 199

    Ibid.

  • 200

    Ibid, [176].

  • 201

    Ibid, [186].

  • 202

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [189].

  • 203

    Ibid, [190].

  • 204

    Ibid, [192].

  • 205

    Ibid, [194].

  • 206

    Ibid.

  • 207

    Ibid, [199].

  • 208

    Ibid, [203].

  • 209

    Ibid, [204].

  • 210

    Ibid, [205].

  • 211

    Ibid, [205]–[212].

  • 212

    Certain Activities (International Court of Justice, General List Nos 150 and 152, 16 December 2015), [216].

  • 213

    Ibid, [217].

  • 214

    Jutta Brunnée, ‘Procedure and Substance in International Environmental Law: Confused at a Higher Level?’ (2016) 5(6) ESIL Reflections 1, 2.

  • 215

    Sands and Peel (n 3) 710.

  • 216

    Draft Articles on Prevention (n 35) 151.

  • 217

    See, eg, Sands and Peel (n 3) 621; Neil Craik, The International Law of Environmenal Impact Assessment (CUP, Cambridge 2008) 120–21. States may have to comply with stricter guidelines if they are party to the Convention on Environmental Impact Assessment in a Transboundary Context, opened for signature 25 February 1991, 1989 UNTS 309 (entered into force 10 September 1997). However, with the exception of Canada, this agreement has only been ratified by European states. See United Nations Treaty Series, Convention on Environmental Impact Assessment in a Transboundary Context <https://treaties.un.org/Pages/showDetails.aspx?objid=080000028002887c>.

  • 218

    Murase (n 8) 9.

  • 219

    Boyle (n 7) 237.

  • 220

    Ibid.

  • 221

    Redgwell (n 17) 16.

  • 222

    See also Peel (n 7) 63; Birnie, Boyle and Redgewell (n 14) 147; Dupuy and Hoss (n 34) 227–31.

  • 223

    See also Brunnée (n 214) 4.

  • 224

    Verheyen (n 3) 152–3. However, there is some practice to suggest that states may have a duty of result when it comes to ‘ultra-hazardous’ activities. See, eg

    Kiss Alexandre & Shelton Dinah , ' ‘Strict Liability in International Environmental Law’ ', in Tafsir Malick Ndiaye & Rüdiger Wolfrum (eds), Law of the Sea, Environmental Law and Settlement of Disputes , ( Brill Nijhoff , Leiden 2007 ) 1131 - 1140 .

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    Jenks C Wilfred , Liability for Ultra-Hazardous Activities in International Law , ( Brill Nijhoff , Leiden 1966 ) Recueil des Cours .

    Sands and Peel (n 3) 97, 712.

  • 225

    Brunnée (n 214).

  • 226

    Ibid.

  • 227

    Ibid, 7.

  • 228

    Ibid.

  • 229

    For a discussion of causation and climate change, see Christina Voigt, ‘State Responsibility for Climate Change Damages’ (2008) 77 Nordic Journal of International Law 1, 15–16. For a discussion of causation and geoengineering, see Ralph Bodle, ‘Geoengineering and International Law: The Search for Common Legal Ground’ (2010–2011) 46 Tulsa Law Review 305, 306–07.

  • 230

    Brunnée (n 214).

Affiliations

Brent, Kerryn Anne - Lecturer, Faculty of Law, University of Tasmania