15 August 2025
When Custom Binds All States
The ICJ affirmed that States have binding customary obligations to prevent significant harm to the climate system and to cooperate in addressing the crisis. Rejecting arguments that climate treaties override these duties, the Court clarified that non-parties remain bound. While acknowledging law’s limits, the ICJ’s opinion provides a powerful legal foundation to guide climate negotiations, litigation, and collective action worldwide. Continue reading >>
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12 August 2025
A Panoply of Consequences?
Among the most significant – but underexplored – aspects of the ICJ’s climate advisory opinion is its treatment of reparations and remedies. This blog post unpacks the legal consequences outlined by the ICJ, examining what the opinion says – and does not say – about how climate-related harm should be remedied. At the heart of this analysis lies a central question: can the affirmation of legal responsibility, without clear guidance on the design of reparations, meaningfully advance climate justice? Continue reading >>
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11 August 2025
Harmonizing Sources, Hardening Duties
The ICJ’s advisory opinion on climate change may come to be remembered as the moment international law explicitly rose to the climate challenge. Yet, what the opinion offers is not a new edifice but a sturdier legal architecture. By advancing an “all of the above” approach to international law’s sources; by treating these sources as interlocking parts of a living legal system; and by recognizing erga omnes and erga omnes partes duties with concrete consequences for responsibility, the Court has given States, courts and litigants a legally rigorous, source‑sensitive map. Continue reading >>
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08 August 2025
Of Warming and Warzones
Despite mounting attention to the impacts of military activities and conflicts on climate mitigation and adaptation in recent years, the issue remains largely absent from international legal scrutiny. Therefore, the very fact that several States and organizations raised it during the advisory proceedings held last December left the few scholars and practitioners working on this issue hopeful. This post reviews how the issue of armed conflicts and military emissions was addressed during the ICJ advisory proceedings. Despite the ICJ’s silence, the post highlights a few interpretative openings that may have legal implications for the regulation of wartime climate harms and explores what the ICJ’s ruling means for the legal visibility and accountability of military emissions. Continue reading >>
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07 August 2025
State Responsibility and the ICJ’s Advisory Opinion on Climate Change
After the International Court of Justice (ICJ) issued its advisory opinion on Obligations of States in Respect of Climate Change, many observers were quick to conclude that it “[opens] the door to a cascade of lawsuits” (Politico). The opinion is indeed an important confirmation that the rules of State responsibility apply in the climate change context. In this post, I assess the ICJ’s treatment of State responsibility in light of the particularities of climate change, especially the plurality of States that contribute to, and suffer from, climate harm. The advisory opinion places trust in the capabilities and flexibility of the applicable rules, yet defers complex decisions on questions like causation to a case-by-case assessment. Continue reading >>
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07 December 2024
„Das IGH-Gutachten könnte die globale Klimagovernance grundlegend ändern.“
Fünf Fragen an Tejas Rao, Marie-Claire Cordonier Segger and Markus Gehring Continue reading >>
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07 December 2024
“The Advisory Opinion Could Reshape Global Climate Governance.”
Five Questions to Tejas Rao, Marie-Claire Cordonier Segger and Markus Gehring Continue reading >>
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31 July 2024
Relationalizing the EU’s Fundamental Rights Responsibility
Human rights law traditionally governs a three-part relationship which connects the individual, the state, and its territory. The design of the EU’s Integrated Border Management (IBM) governance model eschews the applicability and enforceability of international and European human (fundamental) rights law by significantly reconfiguring the relationship between each of these three prongs. This contribution maps how these three traditional triggers for the applicability of human rights law are increasingly evaded in EU IBM policies, the responses to these evasion techniques and how a relational turn in the determination of human rights responsibility may be inevitable. Continue reading >>
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29 July 2024
Beyond Borders
The question of extraterritoriality has found a very particular application in contexts of migration. This renders the questions of which state has to fulfill human rights obligations while a migrant is on the move and to what extent very pressing ones. This symposium examines what the existing criteria for attribution exactly mean for states’ extraterritorial obligations and responsibility in a migration context and whether arguments from other fields of law could either inspire or be implemented beyond their respective borders. Continue reading >>
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08 October 2021
Balancing Accountability and Legitimacy
As they have installed themselves as the de facto government of Afghanistan, the Taliban could theoretically be held accountable for potential crimes via inter-state proceedings. In practice however, that would run the risk of increasing the perceived legitimacy of the Taliban as the Afghan government. The announcement of Prosecutor Karim Ahmad Khan of the International Criminal Court on September 27 to resume investigations in Afghanistan in the form of criminal prosecution – and thus not as inter-state litigation – therefore deserves support. Continue reading >>
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