The contributions of the International Court of Justice to International Environmental Law
International law deals with ESG and in particular with the protection of the environment through a variety of very different instruments, ranging from treaties to soft law. Determining whether provisions relating to environmental matters reflect customary international law is complex and requires a case-by-case analysis. It is clear, however, that the International Court of Justice ('ICJ') is best placed to elucidate the status of these provisions in international law, or at the very least to contribute to the discussion. Whether it has done either of these things is debatable, with its contribution in the environmental field to date being far from transformational.
The ICJ has considered environmental matters in a handful of cases. These include Legality of the Threat or Use of Nuclear Weapons,[1] Gabcíkovo-Nagymaros,[2] Pulp Mills,[3] Whaling in the Antarctic,[4] Certain Activities Carried Out by Nicaragua in the Border Area, and Construction of a Road in Costa Rica.[5] This article analyses the instances in which the ICJ has discussed principles of international environmental law and the extent to which it has deemed them part of customary international law. It concludes with an overall assessment of the ICJ's contributions to the field so far and what its future, perhaps proximate, contributions might be.
Principle of prevention
The principle of prevention of environmental harm was first addressed by the ICJ in 1996, in its advisory opinion on the Legality of the Threat or Use of Nuclear Weapons. It acknowledged that:
The 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.[6]
The following year, in its judgment in Gabcíkovo-Nagymaros, the ICJ went a step further in that it specified that the principle of prevention also entails the need to continually assess a State's ongoing actions, even referring to the concept of sustainable development:
Throughout the ages, mankind has, for economic and other reasons, constantly interfered with nature. In the past, this was often done without consideration of the effects upon the environment. Owing to new scientific insights and to a growing awareness of the risks for mankind - for present and future generations - of pursuit of such interventions at an unconsidered and unabated pace, new norms and standards have been developed, set forth in a great number of instruments during the last two decades. Such new norms have to be taken into consideration, and such new standards given proper weight, not only when States contemplate new activities but also when continuing with activities begun in the past. This need to reconcile economic development with protection of the environment is aptly expressed in the concept of sustainable development.[7]
More than a decade later, in Pulp Mills, the ICJ had the chance to once again address the principle of prevention of environmental transboundary harm, confirming that it is part of customary international law.[8]
Precautionary principle
In contrast to the principle of prevention, the precautionary principle has not been as clearly established in the ICJ's decisions.[9] According to this principle, States need to assess whether a specific action or policy entails environmental risks before proceeding with it, while 'lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation'.[10] One of the main consequences of this as a binding principle could be that, under specific circumstances, the burden of proof shifts, and a claimant that considers that the respondent has not taken the environmental consequences of its actions into account would not bear the burden of proving so. Rather, the respondent may be required to show that it did, in fact, conduct such a risk analysis.
In Pulp Mills, the ICJ did entertain the precautionary principle, albeit not as a principle that States were obliged to follow but rather as an interpretative 'approach' to international environmental obligations, which 'may be relevant in the interpretation and application of the provisions of the [1975] Statute [of the River Uruguay]', but that 'it does not follow that it operates as a reversal of the burden of proof'.[11] Among those who expressed criticisms against this decision was Judge Cançado Trindade, who regretted that the ICJ had not 'asserted or endorsed the general principles of International Environmental Law (such as those of prevention and precaution)'.[12]
The ICJ's stance echoes the 1995 Order pursuant to the Request for an Examination of the Situation in accordance with paragraph 63 of the Court's Judgment of 20 December 1974 in the Nuclear Tests (New Zealand v France). Here, the ICJ also shunned the precautionary principle, which had been invoked by New Zealand,[13] causing Judge Weeramantry to criticise the ICJ's failure to engage with the 'seminal principles of the evolving corpus of international environmental law'.[14]
In Whaling in the Antarctic, the key point was whether specific whaling activities by Japan were for the 'purposes of scientific research' and thus lawful under the International Convention for the Regulation of Whaling ('ICRW').[15] It was first for Japan to explain the 'objective basis' of its determination that its whaling activities, which included lethal methods, were carried out for scientific research purposes.[16] However, scientific uncertainty as to the availability of non-lethal alternatives provided no basis to conclude that the use of lethal methods was unreasonable per se and apparently had no impact on the burden or standard of proof in the case.[17] While the ICJ's judgment did not address the precautionary principle as such,[18] its approach to scientific uncertainty was arguably conservative in light of this principle's basic requirement as regards this kind of uncertainty.[19]
Obligation to notify and consult
As early as in the 1973 Nuclear Tests Cases (New Zealand v France and Australia v France), the ICJ had already established that '[t]rust and confidence are inherent in international co-operation, in particular in an age when this co-operation in many fields is becoming increasingly essential.'[20]
In international environmental law, the obligation to notify is related to the obligation to consult. In the ICJ's own words:
[T]he obligation to notify is intended to create the conditions for successful co-operation between the parties, enabling them to assess the plan's impact on the river on the basis of the fullest possible information and, if necessary, to negotiate the adjustments needed to avoid the potential damage that it may cause.[21]
In practice, however, enforcing the obligation to notify and consult has not always been aligned with the prioritisation of environmental obligations. For instance, in Pulp Mills, although the ICJ found that Uruguay had not complied with its obligation to notify and consult, the ICJ refused to order Uruguay to dismantle the pulp mill in question, considering that the mere declaration of the breach constituted satisfaction for Argentina.[22]
Conversely, in Gabcíkovo-Nagymaros the ICJ found that the parties to the dispute had needed to collaborate in order to determine the environmental consequences of the project and find a common solution.[23] Furthermore, it affirmed an obligation to notify and consult with the potentially affected State in Costa Rica v Nicaragua whenever 'the environmental impact assessment confirms that there is a risk of significant transboundary harm'.[24]
Environmental Impact Assessment
As will be discussed in more detail below, in its 1996 advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, the ICJ had already alluded to States' obligation to assess the impact of warfare on the environment.[25] In Gabcíkovo-Nagymaros, the Court affirmed that the requirement to assess environmental risks 'on a continuous basis' had become by then (1997) much stronger than in the 1970s.[26]
More recently, in Pulp Mills, the ICJ stated that general international law requires an environmental impact assessment ('EIA') 'where there is a risk that the proposed industrial activity may have a significant adverse impact in a transboundary context'.[27] But it also conceded that the scope of this obligation was not defined by international law and was therefore left for each State to regulate.[28] The ICJ did, however, specifically address whether affected populations had to be consulted as part of an EIA, stating that they didn't under specific instruments invoked by Argentina.[29] Whether this finding is true more generally is less clear, and the ICJ probably could have but did not address the position as to the consultation of affected populations under general international law.
In the end, the ICJ in Pulp Mills found that Uruguay had failed to notify Argentina of the outcome of its EIAs before the former adopted its environmental viability decision.[30] Prior notification enables 'the notified party to participate in the process of ensuring that the assessment is complete'.[31] As noted, however, for the ICJ a mere declaration that the procedural obligation had been breached constituted adequate reparation (through satisfaction).[32]
In Costa Rica v Nicaragua, both parties agreed that under general international law States are under 'an obligation to conduct an EIA concerning activities carried out within a State's jurisdiction that risk causing significant harm to other States'.[33] The ICJ clarified that its statement in Pulp Mills about the requirement to undertake an EIA 'applies generally to proposed activities which may have a significant adverse impact in a transboundary context' and not just to industrial activities.[34] It also stated that '[d]etermination of the content of the environmental impact assessment should be made in light of the specific circumstances of each case', but otherwise confirmed the observation in Pulp Mills that it is for each State to determine the specific content of EIAs[35] (thus throwing no further light on any required content).
Environmental protection during times of armed conflict
The ICJ has had the opportunity to analyse the obligation on States to protect the environment not only during peacetime, but also during times of armed conflict. In Legality of the Threat or Use of Nuclear Weapons, it weighed in on whether States need to ensure that their activities do not harm the environment even when engaging in armed conflict.
On the one hand, the ICJ examined the customary principles governing armed conflict and how they interact with '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', which it deemed 'is now part of the corpus of international law relating to the environment.'[36] In the ICJ's view, States need to consider the environmental impact of military acts when assessing these acts' compliance with the principles of necessity and proportionality.[37] But it also ruled that this shall not prevent a State from exercising its right to self-defence.[38]
On the other hand, the ICJ also took into consideration the specific obligations regarding environmental protection in Articles 35(3) and 55 of Additional Protocol I to the Geneva Conventions,[39] observing that:
Taken together, these provisions embody a general obligation to protect the natural environment against widespread, long-term and severe environmental damage; the prohibition of methods and means of warfare which are intended, or may be expected, to cause such damage; and the prohibition of attacks against the natural environment by way of reprisals.[40]
These obligations, however, were only considered binding on States who were parties to Additional Protocol I, as they apparently had not entered the corpus of customary international law – at least not when the opinion in Legality of the Threat or Use of Nuclear Weapons was issued.[41]
Climate change
To date, the ICJ has not yet ruled on the specific topic of whether States are obliged to prevent climate change and, if so, what the content of such an obligation might be.[42] The ICJ has, however, addressed the importance of preserving the environment for future generations, as well as the need to take into account not only the immediate but also the long-term effects of environmental damage.
In Legality of the Threat or Use of Nuclear Weapons, the ICJ 'recognize[d] that the environment is not an abstraction but represents the living space, the quality of life and the very health of human beings, including generations unborn.'[43] In Gabcíkovo-Nagymaros, it considered that 'a “peril" appearing in the long term might be held to be “imminent" as soon as it is established, at the relevant point in time, that the realization of that peril, however far off it might be, is not thereby any less certain and inevitable.'[44]
Besides these references to the long-term impact of environmental harm, the ICJ's contribution to the development of the specific obligations surrounding climate change has been, thus far, underwhelming. Its ability to pronounce on a given matter is, of course, dependent on the cases that States submit to it. At present, the ICJ has a unique opportunity to opine on this matter as a result of a United Nations' General Assembly request for an advisory opinion, which requests the ICJ to clarify both the international law obligations of States regarding climate change and the consequences that the breach of such obligations entail.[45]
Conclusion
As an international court of unparalleled authority, the ICJ has no doubt contributed to the development of international environmental law, for example by consolidating the principle of prevention (which has a long history in international law), and progressively clarifying the scope of States' environmental obligations to notify and consult and undertake EIAs in certain circumstances. However, the ICJ has been considerably more cautious as regards other key aspects of international environmental law, including the environmental rules applicable during armed conflicts and the precautionary principle. The ICJ will hopefully provide further insights on these issues when it delivers its advisory opinion on the obligations of States in respect of climate change. This would follow neatly in the steps of the International Tribunal for the Law of the Sea, which in its own recent advisory opinion on climate change has stressed 'the deleterious effects climate change has on the marine environment and the devastating consequences it has and will continue to have on small island States',[46] and the importance of the precautionary approach and of respecting procedural obligations, such as the requirement to conduct an EIA, for the protection of the marine environment.[47]
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[1] Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 ICJ Reports, p 226 ('Legality of the Threat or Use of Nuclear Weapons').
[2] Gabcíkovo-Nagymaros Project (Hungary/Slovakia), Judgment, 1997 ICJ Reports, p 7 ('Gabcíkovo-Nagymaros').
[3] Pulp Mills on the River Uruguay (Argentina v Uruguay), Judgment, 2010 ICJ Reports, p 14 ('Pulp Mills').
[4] Whaling in the Antarctic (Australia v Japan: New Zealand intervening), Judgment, 2014 ICJ Reports, p 226 ('Whaling in the Antarctic').
[5] 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, 2015 ICJ Reports, p 665 ('Costa Rica v Nicaragua'). The ICJ joined the proceedings in these two cases. See id., para 19.
[6] Legality of the Threat or Use of Nuclear Weapons, para 29.
[7] Gabcíkovo-Nagymaros, para 140.
[8] Pulp Mills, paras 101, 139.
[9] For an early reference to 'the need to take environmental concerns seriously and to take the required precautionary measures', agreed by both parties to the dispute, see Gabcíkovo-Nagymaros, para 113.
[10] The Rio Declaration on Environment and Development (1992), Principle 15.
[11] Pulp Mills, para 164.
[12] Ibid, Separate Opinion of Judge Cançado Trinidade, para 46.
[13] Request for an Examination of the Situation in Accordance with Paragraph 63 of the Court's Judgment of 20 December 1974 in the Nuclear Tests (New Zealand v France) Case, 1995 ICJ Reports, p 288, paras 5, 34–35 ('Nuclear Tests')
[14] Ibid, Dissenting Opinion of Judge Weeramantry, pp 342–344, 362.
[15] Whaling in the Antarctic, paras 30, 42.
[16] Ibid, para 68.
[17] Ibid, para 135. See also Pulp Mills, paras 225, 228, 259, 264, 265 (noting that Argentina had presented no 'clear', 'convincing' or 'conclusive' evidence of pollution over permissible levels); Costa Rica v Nicaragua, para 119 (no 'convincing evidence' produced of sediments having been deposited on the river's bank).
[18] Whaling in the Antarctic, Separate Opinion of Judge Cançado Trinidade, para 70.
[19] Ibid, Separate opinion of Judge ad hoc Charlesworth, paras 6, 9 (arguing that '[t]he precautionary approach to environmental regulation also reinforces this analysis of the conditions in which lethal research methods may be undertaken' and that 'treaties dealing with the environment should be interpreted wherever possible in light of the precautionary approach, regardless of the date of their adoption').
[20] Nuclear Tests, p 253, para 46; Nuclear Tests, p 457, para 49.
[21] Pulp Mills, para 113.
[22] Ibid, para 269.
[23] Gabcíkovo-Nagymaros, para 140.
[24] Costa Rica v Nicaragua, para 104.
[25] Legality of the Threat or Use of Nuclear Weapons, para 30.
[26] Gabcíkovo-Nagymaros, para 112.
[27] Pulp Mills, para 204.
[28] Ibid, para 205. States must however exercise due diligence in conducting EIAs, which must be undertaken before the implementation of the project and continuously throughout the project's life.
[29] Ibid, para 216.
[30] Ibid, paras 119-122.
[31] Ibid, para 119.
[32] Ibid, para 269.
[33] Costa Rica v Nicaragua, para 101.
[34] Ibid, para 104. See also para 153. But see id, separate opinions of Judge Owada, paras 18, 21 and of Judge Donoghue, paras 13, 20 (doubting that a specific obligation to conduct EIAs exists under general international law).
[35] Ibid.
[36] Ibid, para 29.
[37] Ibid, para. 30.
[38] Ibid, para. 30.
[39] Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I), 8 June 1977.
[40] Legality of the Threat or Use of Nuclear Weapons, para. 31.
[41] Ibid. See, however, Principle 12 of the International Law Commission's Draft principles on protection of the environment in relation to armed conflicts 2022. United Nations General Assembly, Protection of the environment in relation to armed conflicts, A/RES/77/104, 19 December 2022.
[42] Some States have resorted to arguments relating to climate change in proceedings before the ICJ. For instance, Japan referred to the need to address the effects of climate change and global warming as one of the goals of its whaling research program that was challenged by Australia. In the end, the ICJ found that special permits granted by Japan to kill, take and treat whales under this research program were not in conformity with the ICRW. Whaling in the Antarctic, paras 116, 149, 247.
[43] Nuclear Tests, para 29.
[44] Gabcíkovo-Nagymaros, para 54.
[45] Request for Advisory Opinion transmitted to the Court Pursuant to General Assembly Resolution 77/276 of 29 March 2023, Obligations of States in Respect of Climate Change.
[46] Request for an Advisory Opinion submitted by the Commission of Small Island States on Climate Change and International Law, Case No. 31, ITLOS, Advisory Opinion, 21 May 2024, para 122.
[47] Ibid, paras 213, 345.
