{"id":27210,"date":"2025-09-23T07:00:50","date_gmt":"2025-09-23T12:00:50","guid":{"rendered":"https:\/\/blogs.law.columbia.edu\/climatechange\/?p=27210"},"modified":"2025-09-18T16:49:21","modified_gmt":"2025-09-18T21:49:21","slug":"shared-blame-shared-bill-joint-and-several-state-liability-as-a-proposed-legal-framework-for-climate-reparations","status":"publish","type":"post","link":"https:\/\/blogs.law.columbia.edu\/climatechange\/2025\/09\/23\/shared-blame-shared-bill-joint-and-several-state-liability-as-a-proposed-legal-framework-for-climate-reparations\/","title":{"rendered":"Shared blame, shared bill? Joint and several State liability as a proposed legal framework for climate reparations"},"content":{"rendered":"

As climate litigation continues to rise, a pivotal and unresolved legal question emerges in the law of State responsibility: how to allocate responsibility for injuries that result from the cumulative conduct of multiple actors.\u00a0<\/span><\/p>\n

Climate-related injury derives from the aggregate and diffuse effect of anthropogenic activities, as well as natural events, in which the actions of both States and non-State actors across extended temporal horizons are involved \u2013as recently highlighted by both the <\/span>IACtHR in its Advisory Opinion of 29 May 2025 on the Climate Emergency and Human Rights<\/span><\/a>, \u00b6\u00b644 <\/span>et seq<\/span><\/i>, and the <\/span>ICJ in its Advisory Opinion on Obligations of States in respect of Climate Change<\/span><\/a> (\u201cICJ Advisory Opinion\u201d), \u00b6421\u2013. Such a reality may render precise causal tracing between the conduct and harm inherently difficult or even impossible.<\/span><\/p>\n

While the ICJ has acknowledged that the rules on State responsibility are, in principle, \u201ccapable of addressing situations in which there exists a plurality of injured or responsible States\u201d in the context of climate change (ICJ Advisory Opinion, \u00b6430), it leaves many open questions to be resolved on a case-by-case basis. The multi-actor, multi-temporal nature of climate harm may make attribution and causation standards in international law ill-suited to safeguard the victims\u2019 right to full reparation.<\/span><\/p>\n

This post proposes joint and several liability, a well-known principle drawn from domestic torts, as a potential legal solution to address these challenges in the law of State responsibility. By shifting the burden of attribution away from victims, this doctrine may arguably promote more accessible remedies and greater accountability.<\/span><\/p>\n

The law of State responsibility in cases of multiple causation<\/b><\/h2>\n

The ICJ Advisory Opinion considers that the rules on State responsibility under customary international law sufficiently address the issue of multiple States contributing to the same damage (\u00b6430). Yet it acknowledges that the most pressing questions on State responsibility for breaches of climate change obligations \u2013namely, issues of attribution, causation and apportionment\u2013, necessitate <\/span>in concreto<\/span><\/i> assessment (\u00b6\u00b697, 108, 423, 437). The overly simplistic approach taken by the ICJ Advisory Opinion in this regard has been criticized by Judges Yusuf (<\/span>separate opinion<\/span><\/a>, \u00a7\u00a7II and VI) and Nolte (<\/span>declaration<\/span><\/a>, \u00a7II). (For a review of the ICJ Advisory Opinion\u2019s view on the legal consequences of breaching climate change obligations under the law of State responsibility, see <\/span>here<\/span><\/a> and <\/span>here<\/span><\/a>).<\/span><\/p>\n

The law of State responsibility, as codified in the <\/span>International Law Commission\u2019s Articles on State Responsibility for Internationally Wrongful Acts<\/span><\/a> (\u201cARSIWA\u201d), only partially addresses the problem of multiple causation. Article 47 states that where multiple States are responsible for the same internationally wrongful act, each may be held responsible for the act as a whole, thus preventing any State from evading responsibility due to a minimal contribution (as asserted by the ICJ Advisory Opinion, \u00b6431). On its part, Article 31 affirms that a responsible State must make full reparation for the injury caused by its wrongful act.\u00a0<\/span><\/p>\n

The <\/span>International Law Commission\u2019s commentaries<\/span><\/a> clarify that factual causation \u201cis a necessary but not a sufficient condition for reparation\u201d, and that other elements \u2013such as foreseeability, proximity, or the scope of the breached obligation\u2013 may influence the right to reparation [commentary (10)]. The <\/span>commentaries<\/span><\/a> also further that where injury arises from concurrent causes, reparation should still be granted unless the injury is too remote or can be severed [commentary (13)], and that State practice does not support the attenuation of the reparation merely because there are other contributory causes, except in cases of contributory fault under Article 39 ARSIWA [commentary (12)].<\/span><\/p>\n

However, international practice has not consistently applied such an approach. In several cases, international courts and tribunals have imposed restrictive causation requirements for awarding reparation, limiting compensation to injuries that are directly and clearly linked to a State\u2019s conduct (see, e.g. some <\/span>decisions<\/span><\/a> issued by the UN Compensation Commission panels following Iraq\u2019s unlawful invasion and occupation of Kuwait). In the <\/span>2022 <\/span>Armed Activities<\/span><\/i> reparations judgment<\/span><\/a>, the ICJ reaffirmed its traditional causation standard of a \u201csufficiently direct and certain causal nexus\u201d between the wrongful act and the injury (\u00b693), while acknowledging the evidentiary limits for apportioning certain types of damages for which factual causality was unclear (e.g., \u00b6\u00b6177, 221, 253). (For a deeper view on how international judicial practice approaches causation, see <\/span>Plakokefalos [2015]<\/span><\/a>, <\/span>Lanovoy [2022]<\/span><\/a> and <\/span>Nollkaemper [2024]<\/span><\/a>.)<\/span><\/p>\n

In the ICJ\u2019s view, the \u201csufficiently direct and certain\u201d causation standard is \u201cflexible enough\u201d to address the challenges arising from complex, multi-causal contexts, such as climate change (ICJ Advisory Opinion, \u00b6436), while the apportionment of responsibility must be resolved on a case-by-case basis (<\/span>ibid.<\/span><\/i>, \u00b6432). However, such an assessment deliberately ignores the limits of State responsibility.\u00a0<\/span><\/p>\n

As was pointed out by Judges Yusuf (<\/span>separate opinion<\/span><\/a>, \u00b642) and Nolte (<\/span>declaration<\/span><\/a>, \u00b616), a State\u2019s duty to make reparation under ARSIWA arises only when an internationally wrongful act can be established. Yet many injurious acts or omissions contributing to climate change may not meet that threshold. Moreover, climate change derives from the uncoordinated and cumulative actions and omissions of both State and non-State actors over time. Such a scenario, which has traditionally been contemplated in strict liability schemes for hazardous activities (see, e.g., the <\/span>ILC preparatory work of the 2006 Draft principles on the allocation of loss in the case of transboundary harm arising out of hazardous activities<\/span><\/a>), stands in sharp contrast to concerted practices that may lead to the responsibility of multiple State actors as envisaged under Article 47 ARSIWA.<\/span><\/p>\n

This situation risks creating a significant accountability gap and depriving victims of full reparation under the current model of international responsibility. In this context, the application of joint and several liability seeks to bridge some of these gaps in scenarios of indivisible injury and complex causation.<\/span><\/p>\n

The joint-and-several approach to climate harm<\/b><\/h2>\n

Judge Simma, in his <\/span>separate opinion in the 2003 <\/span>Oil Platforms<\/span><\/i> case<\/span><\/a>, identified the principle of joint and several liability as a potential solution for the problem of overdetermination in the law of State responsibility. In his view, the doctrine amounted to a general principle of international law drawn from domestic practice, whereby multiple wrongdoers contributing to an indivisible injury may each be held liable for the full extent of the injury, even if their individual conduct alone would not have led to the injury. This reasoning is particularly relevant to climate change reparations, where losses and damages are often non-severable and no single State is solely responsible for the injurious outcome.<\/span><\/p>\n

The principle of joint and several liability has already found expression in certain international legal regimes. The <\/span>1972 Convention on International Liability for Damage Caused by Space Objects<\/span><\/a> (\u201c1972 Space Liability Convention\u201d) provides that where \u201ctwo or more States jointly launch a space object, they shall be jointly and severally liable for any damage caused\u201d by the objective, and thus a claimant may seek full compensation from any of the launching States. Similarly, <\/span>Annex VI to the Protocol on Environmental Protection to the Antarctic Treaty<\/span><\/a> \u2013although not yet in force\u2013 proposes joint and several liability for environmental emergencies involving multiple operators, unless it can be shown that the environmental emergency is severable. These examples reflect a normative effort toward ensuring full redress for victims in cases involving hazardous activities with diffuse causation.<\/span><\/p>\n

The application of the doctrine of joint and several liability in the context of climate change offers several potential benefits:<\/span><\/p>\n