Custom, Entrenchment, Interpretation

The vision of international climate change law is as simple as it is unassailable: Keeping the world a liveable place for humans all over the planet. As modest as this vision might sound, it still is a vision, i.e. a substantive conception of what the future should look like. Thus, having to fight climate change is having to shape the future. International rules and conventions tackling the current climate crisis have therefore always been among the most prominent exponents of international law’s orientation toward the future. Whereas large parts of classic international law – such as the rules protecting state sovereignty or governing treaty relations –  primarily aim to safeguard the conditions necessary for the collective self-regulation of states, international climate change law contains norms designed to substantively shape the world’s future state: By calling for mitigation, these norms commit states to upholding the status quo (“stabilization of greenhouse gas concentrations in the atmosphere” – emphasis added), as it is considered worth preserving for the future. At the same time, by requiring adaptation, they call for change to make the world more resilient and less vulnerable to the consequences of climate change than it is today (these dimensions might be labelled as “safeguarding the future” [”Zukunftssicherung”] and “shaping the future” [“Zukunftssteuerung”] respectively, see here, p. 68 et seq.). In a couple of to some extent inconspicuous ways, the ICJ’s advisory opinion on Obligations of States in Respect of Climate Change sharpens the contours of this substantive grasp for the future. In this post, I will focus on three of them: The customary status of climate change obligations (I), their qualification as obligations erga omnes (II) and, most importantly, the Court’s finding that intergenerational equity serves as a guiding interpretative principle (III).

Conceptualising the Future through Custom 

It is first and foremost by strengthening states’ mitigation obligations, that the advisory opinion contributes to defining – and in fact expanding (for a similar assessment see the analysis by Julian Arato and Justina Uriburu at EJIL:Talk!) – international law’s conception of the future. In contrast to what some states claimed during the course of the proceedings (see inter alia here, pp. 61 et seqq. and here, pp. 31 et seqq.), the Court clarified without any further ado that the protection provided by the customary principle of prevention extends to the climate system as well, as it forms “an integral and vitally important part of the environment” (para. 273). Considering international law’s turn to the future, this is important for two reasons: First, because the substantive vision of the future that customary international law pursues is broadened. It now encompasses an undamaged climate system – or at least one that compared to its current state has not suffered further significant harm. Second, as has already been noted (see here), protecting the climate system under the customary principle of prevention expands the range of duty-bearers under international law’s future-oriented obligations. Even states that are not parties to the treaty framework on climate change, namely the UNFCC, the Kyoto Protocol and the Paris Agreement, are now legally held to contribute to the fight against climate change and, hence, to the realization of international law’s idea of what the future should look like. 

Securing the Future by Entrenchment

Quite remarkably, the court adds that these customary obligations protect a common interest of all states and consequently qualify as obligations erga omnes (para. 440). While the advisory opinion elaborates on the effects of this qualification for the question of ius standi (paras. 441 et seqq., for a deeper analysis of this aspect of the opinion see here), it has remained largely unnoticed, that it also provides these obligations with a form of legal entrenchment, that makes them immune against almost any attempt to evade or disengage from them in the future. As Art. 41 (1) (b) VCLT demonstrates for treaty relations, bilateral modifications or exemptions are no longer an option once every state has a legally protected interest in upholding of the respective obligations. To customary international law this applies as well. Hence, except for the highly unlikely case of a sufficiently universal desuetude with regard to the principle of prevention, there is no way out of the respective climate change obligations. It follows that states’ obligations to preserve the climate system and thus to contribute to international law’s vision for the future are itself rendered future-proof. The ICJ may not have followed in the footsteps of the Inter-American Court of Human Rights, that in its own advisory opinion on “The Climate Emergency and Human Rights” (Advisory Opinon 32/25, para. 291) has declared the prohibition of irreversible harm to the environment, including the climate system, part of jus cogens. But in terms of temporality, the effects of its finding that the prevention principle contains obligations erga omnes are not that different. Neither the obligation nor the vision of the future it purports are going to go away any time soon.

Shaping the Future through Legal Interpretation

This rather firm grip on the future seems to be somewhat at odds with the fact, that explicit references to the rights of future generations are – except for the occasional quotes from the General Assembly’s request or the preamble of one of the climate change treaties – rather hard to find in the Court’s Advisory Opinion. Although the court directly mentions “generations unborn” in the context of states obligations to protect the environment (para. 155), the Court’s silence on the not-yet-living is particularly striking in the human rights context. Taking into account that the most severe consequences of a failure to act now will materialize only after the life-span of current generations has ended and considering that most mitigation efforts will not yield success in the immediate future, the rights to life and a healthy environment would, in my opinion, have suggested a more detailed analysis of those questions. And it does not come as a surprise, that the General Assembly had in its request for the Advisory Opinion, explicitly asked the Court to delineate the obligations that States bear to protect “present and future generations” and even demanded to outline the consequences of violations of those duties “with respect to […] [p]eoples and individuals of the present and future generations”. In one of the many individual declarations appended to the Opinion Vice-President Sebutinde understandably deplores the reluctance of the Court to deal with this particular aspect of the question put to it (see here, para. 7). And it is in this regard that the Court could have adopted a more future-oriented stance.  

It would not do justice to the opinion, though, to accuse the Court of outlining states’ future-shaping obligations without having due regard to future generations and their (presumed) interests. Instead, in one of the rather jaw-dropping paragraphs of the opinion, the Court acknowledges intergenerational equity as a principle that – although not establishing self-standing obligations – guides the interpretation of applicable rules (para. 157, 161). This principle, according to the court, gives “expression [to] the idea that present generations are trustees of humanity tasked with preserving dignified living conditions and transmitting them to future generations” (para. 156). And it is these “interests of future generations” that “need to be taken into account where States contemplate, decide on and implement policies and measures in fulfilment of their obligations under the relevant treaties and customary international law” (para. 157). With these brief remarks the Court establishes a previously unarticulated interpretative principle aimed at reinforcing the core imperative of international climate change law: to preserve the world as a liveable place. International law’s ambition to shape the future in this particular way is now a legally recognized and mandatory interpretative consideration. And although the Court initially draws on the preamble of the Paris Agreement to back the legal status of intergenerational equity and in its conclusions only refers to the interpretation of the “most directly relevant legal rules” (para. 161), the interpretative principle it endorses is neither restricted to the former nor to the legal instruments of climate change law in general. Instead, if I read the opinion correctly, it applies to the entirety of international law – for a simple reason: In the Court’s own words, intergenerational equity is nothing but a “manifestation of equity in the general sense and thus shares its legal significance” (para. 157). Equity, however, is – as the Court has found before – a “direct emanation of the idea of justice” and “a general principle directly applicable as law” (para. 152 and see here, para 71 – emphasis added). Given this general character of the underlying principle of equity, it is difficult to see how the realm, that considerations of intergenerational equity apply to, could be restricted to the rules and treaties most directly relevant to questions of climate change. When in doubt, any rule of international law has therefore – according to the ICJ’s interpretative approach – to be applied in a manner that preserves dignified living conditions for future generations. For international law’s orientation toward the future this is a new step. Where in classic international law a restrictive interpretation (in dubio mitius) would have prevailed in order to keep international law’s determinations as minimal as possible, safeguarding states’ regulatory freedoms, the court’s interpretative approach potentially strengthens the realization of the modest vision that international climate change law holds for the future. It is somewhat disappointing that in the later passages of the advisory opinion the Court does not put its novel approach into practice but largely confines itself to the rather abstract statement of principle that I have just sketched. The Court’s finding, for instance, that due diligence requires an environmental impact assessment could have benefitted from drawing on its new interpretative rule: If states are bound to consider the interests of future generations when applying international rules, is the duty to assess how these interests might be affected not an obvious corollary?

Conclusion

When it comes to international law’s turn toward the future, there is no way around international climate change law. The ICJ’s advisory opinion on climate change reinforces this centrality in three key ways: First, by extending the customary principle of prevention to the protection of the climate system it expands international law’s vision of the future to the conservation of the climate; second, by elevating these obligations to the status of erga omnes it safeguards them for the foreseeable future; and third, by declaring intergenerational equity a general principle that guides the interpretation of international legal norms, it obliges States to contribute to international law’s vision of the future. So, if the future should fail to be bright, the Court is not to blame.