In the International Court of Justice’s (ICJ) advisory procedure on international obligations of states in respect of climate change the US government raises the concern that the ICJ could disrupt the cooperative legal system that states have established under the UNFCCC, Kyoto Protocol and the Paris Agreement (PA) through its interpretation of customary law (written statement (WS) USA, paras. 3.7., 6.5.). On its face, it is convincing that causing disruption cannot be the ICJ’s role in these advisory proceedings. Firstly, creating social order is one of the fundamental functions of law. Secondly, it seems especially important to establish order where an existential crisis such as climate change must be managed. Thirdly, law ensures that certain fundamental principles of protection are not abandoned in order to avert a crisis. However, on closer inspection, it becomes clear that climate change itself is disruptive. It forces us to transform our carbon-based economies. This will not work without destroying current economic structures and creating new ones, a process which Schumpeter called creative destruction. This idea of progress through disruption becomes relevant for law itself if external factors such as political mobilisation or, we suggest, ecological necessities disrupt the social order, as this could disturb the connection between the legal and the social order (cf. here). In time, legal change, whether realised through legislatures and/or courts, reconnects the legal and the social order. Questions arise as to the role of law in tackling climate disruption and the existence of a gap between the social understanding of environmental necessities and the legal response to climate change which the ICJ should fill.
Different views on the role of law and the ICJ
In view of the arguments put forward in the advisory proceedings, the states would answer these questions differently. Broadly speaking, there are two main lines of argument. The states most vulnerable to climate change, especially the small island states, including the initiator of the advisory opinion, Vanuatu, and the least developed countries, urge the ICJ to hold major emitters accountable for the damage caused by their (historical) emissions. They refer in particular to the duty of due diligence, the precautionary principle, the principle of prevention, the no-harm rule, international human rights and UNCLOS (cf. WS Vanuatu, paras. 231 and 321 et. seq.; WS COSIS, paras. 79 et seq.). According to them, the duty to prevent, reduce and control the risks of climate change arose when the existence and consequences of man-made climate change were scientifically recognised, and it applies alongside the treaty obligations (e.g. WS Egypt, paras. 304 et seq., 315 et seq.; WS Kiribati, paras. 183 et seq., WS Vanuatu, paras. 228, 235, 399). State responsibility for significant environmental harm would include cessation and full reparation (cf. WS Vanuatu para. 487, 526 et seq.; WS COSIS paras. 178 et seq.; WS Namibia, paras. 130 et seq.; WS Kenya, paras. 6.98, 6.113).
Developed countries and emerging economies argue that customary international law obligations were not applicable before the 1990s, because it was only then that the international community recognized climate change as a common concern requiring state action (cf. WS Switzerland, para. 76; WS Netherlands, para. 5.6.; WS Germany, para. 40; WS Brazil, paras. 30-31; WS Russia, p. 16; WS USA para. 5.4). Some states and organisations like the European Union (EU) advocate for a harmonious interpretation of customary international law with the climate treaty regime (WS EU, paras. 226-230; cf. WS Australia para. 2.62; WS New Zealand, para. 86; WS Colombia, para. 3.9; written comment Mexico, paras. 20, 23). Others argue that the customary obligation to prevent and mitigate significant transboundary environmental harm does not apply to climate change or that the UNFCCC/PA constitute a lex specialis (e.g. WS US, paras. 4.15 et seq., 4.25; WS China, para. 128, 131, 134 et seq.; WS India, para. 17; WS Japan, para. 14; WS Kuwait, paras. 60 et seq.; WS OPEC, para. 62; WS Indonesia, paras. 61, 63). Some maintain that the PA’s specific rules regarding harm caused by climate change take precedence over the general rules of state responsibility (e.g. WS EU, paras. 353-355). Ultimately, many states and organisations contend that the diffuse character of climate change and unresolved scientific and political questions of causation, attribution and differentiation impede the general applicability and/or the application of the rules of reparation in an individual case (WS UK, para. 137.4., WS France, paras. 178, 206, WS New Zealand, para. 140; WS Russia, p. 16 et seq.; WS China, para. 118, 136, 138). Human rights obligations, when acknowledged (critically, WS US, paras. 4.43 et seq.) are interpreted in accordance with the PA as future-oriented procedural obligations to mitigate climate change (cf. WS EU, paras. 272, 274; WS China, paras. 120 et seq.).
These lines of argument provide insights into how states perceive the role of law, the alignment of the legal and the global social order and the need for disruption in relation to climate change. Those emphasising the importance of the treaty regime consider law primarily as a tool to provide the legal structure for politics, i.e. negotiation and cooperation (cf. WS US, paras. 6.3. et seq.). Law’s substantive problem-solving potential is deemed to be limited with respect to the collective action problem of climate protection. Interpreting customary international law in a way that would disrupt the established system of cooperation would be detrimental (cf. WS US, paras. 3.7., 4.1.). Those underlining the importance of customary international law seek to reinforce the role of law in steering state behaviour towards addressing the climate problem equitably. They aspire to progress by disrupting and effectively reversing the trend towards the proceduralisation of climate law, as evidenced in climate treaties that leave problem-solving to political negotiations. That is because even if formally equal, the material inequality of states puts smaller states in a weaker position in negotiations (cf. the protest by small island states at COP 29 ). Moreover, the current treaty regime has not provided an effective global response to climate change (cf. UNEP’s regular assessments).
Progress by disruption in and through international law
Most likely, the ICJ will neither fully endorse nor reject an interpretation that carries the potential for progress through disruption. The interpretative rule that foresees systemic integration of various norms of international law under Art. 31(3)(c) Vienna Convention pushes the ICJ towards legal harmonisation. The International Tribunal for the Law of the Sea (ITLOS) interpreted UNCLOS in the light of the PA in its Advisory Opinion (paras. 214 et seq.), so did the European Court of Human Rights (ECtHR) with the European Convention in its KlimaSeniorinnen case (paras. 434, 455). If not interpreted as lex specialis or as an exhaustive concretization of contemporary customary international law, the ICJ’s interpretation of the PA in light of relevant rules of customary law applicable in relation between the parties and/or customary international law in light of the PA (cf. ICJ, North Sea Continental Shelf, para. 71) could potentially strengthen the role of law in guiding state behaviour towards CO2 reduction, shifting the international response slightly from the political to the legal realm.
Firstly, the ICJ could interpret Art. 4 (1)-(3), 2 (1) PA as containing a duty of due diligence (cf. WS Germany, paras. 42 et seq.; WS EU, paras. 135 et seq.; WS COSIS, paras. 106 et seq.; WS Vanuatu, paras. 408 et seq., 435). Due diligence requires a normative threshold against which the propriety of conduct is assessed. One could say, it is a result-oriented behavioural norm which falls between the mere obligation of conduct and that of result (cf. ICJ, Opinion on the Legality of the Threat or Use of Nuclear Weapons, para. 99; cf. WS EU, paras. 77, 128 et seq.). Similarly, the duty to determine national contributions with progressive ambition (Art. 4 (2), (3) PA) must be assessed against the intended result to stop global warming, which, according to the IPCC, is commensurate with the 1,5 degree Celsius target. According to the ICJ, due diligence requires 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” (Pulp Mills on the River Uruguay, para. 197; cf. ITLOS, para. 234-235). Interpreting the PA in this way would resonate with the human rights obligation to provide a pathway to carbon neutrality by 2050 (see ECtHR, para. 550), put pressure on states to identify their fair share and to determine transparent national contributions consistent with this aim and thereby push states towards a decentralised implementation of the temperature target.
Secondly, the ICJ could amplify social and economic disruption through law by stating that the duty of implementing a treaty in good faith (cf. Art. 26 Vienna Convention; ICJ, Gabčíkovo-Nagymaros Project, paras. 42, 109, cf. WS Vanuatu, para. 312) includes the duty not to jeopardize the treaty’s objective. Any form of investment in fossil fuels in fact risks compromising the goal of the PA to reach carbon neutrality by 2050. Expanding fossil fuels is a negation of progressive ambition and non-regression required under the PA. Should the ICJ find an infringement of the duty to act in good faith, it would effectively force states to replace existing energy supplies based on fossil fuels with new energy supplies (cf. the anti-fossil-fuel treaty initiative).
Invoking human rights catalyses a transition to decarbonisation from the bottom up by disrupting the level-playing-field that states and corporations seek to preserve with respect to CO2-mitigation obligations. For those states that have internally committed to reducing CO2 and have been obliged by human rights courts to consistently adhere to their own CO2-pathways (cf. ECtHR, para. 550), there is a greater incentive to cooperate with other states. A transnational dialogue of courts may lead to common understandings of human rights obligations in relation to climate change which influence the bargaining position of states when entering international negotiations. If seen as a reciprocal process, contrary to being ineffective, relying on human rights could push international negotiations and thus constitute an important element in solving the collective action problem.
Conclusion
To conclude, the ICJ could reinforce economic restructuring towards carbon-neutrality without undermining the trust and security that international climate law is meant to preserve in the process of decarbonization, interpreting the law in a way that promotes creative destruction of old and the building of new economic structures. In this process, legal interpretation is largely future-oriented. Climate justice, in its historical, past-oriented sense, would not be covered. In support of including the past one could adduce that only by undoing past injustices can future progress be achieved. Indeed, a generally accepted function of law is to provide compensation for damages resulting from past conduct to redress wrongs and guide future behaviour. Moreover, delimiting the political discretion that the climate treaty processes have granted to states would strengthen the role of law and the ICJ in climate protection. However, what is wrong in the climate context and must be considered illegal is highly controversial when it comes to historic emissions among states. Recognising an international obligation to make reparation for historical emissions despite the diffuse nature of climate change would amount to an act of judicial disruption. Such a decision would render the concerted treaties largely irrelevant. It would not only put a legal stop to state discretion but could also shake the existing structures of international law. If for better or for worse, it is not likely that an institution which is part of the current system would make such a decision.
