By an inference of facts from the Corfu channel case we understand that there is discussion on causation of harm and attributing climate harm. But on the other hand we talk about multiple states contributing to the risk. Is the State liable only for its share or jointly for the whole harm?

The Court recognises the erga omnes character of certain climate-related obligations but simultaneously affirms the Article 48 ARSIWA distinction between “injured” and “non-injured” States. This as an “artificial” division in the context of obligations owed to the international community as a whole, arguing that in substance all States are “injured” when a breach affects a global common good like the climate system. If all States are equally beneficiaries of an erga omnes obligation, does maintaining a procedural hierarchy between injured and non-injured States dilute the universality of the right to invoke responsibility?

Here, ICJ refers to human rights instruments and jurisprudence to help interpret States' climate-related duties. The use of international human rights law as an interpretative aid for defining scope and content of international environmental obligations. In this backdrop could we use Advisory Opinion 23/17 of the Inter-American Court of Human Rights which states, "healthy environment is autonomous and that States have obligations to prevent environmental harm even beyond their borders when such harm could affect human rights" to justify and demand higher standards of protection?

This shows the contested relationship between treaties and custom. The Paris Agreement's mitigation commitments could thus operate not merely as treaty based obligations but as customary due diligence standards, especially of widely ratified and implemented. This raises questions aboout whether Paris targets, though non-binding in certain aspects, might harden into customary normas through consistent state practice and opinio juris. The ICJ’s phrasing here blurs the line between “treaties are treaties and custom is custom."

Due diligence in international environmental law is context-dependent: what counts as "reasonable" State conduct depends on the best available knowledge and technology at a given time. In 1990, meeting du diligence might have meant setting basic emissions limits. In 2005, it might have required adopting renewable energy targets. In 2025, it could demand deep decarbonisation pathways in line with the latest IPCC scenarios. This is linked to the principle of progressive development and adaptive management in environmental law. States must continuously adjust policies in light of evolving scientific and technological capacity.

The ICJ affirms the no harm principle's dual structure: a preventive duty and a reparative duty. Traditionally, in environmental law, the preventive limb is dominant as emphasised in the cases of Trail Smelter, Pulp Mills because prevention is seen as more effective. However, the climate change context presents a challenge. Harm to the environment has been ongoing for decades and is cumulative and in many respects irreversible. This raises the question, how can a preventive strategy function effectively where the damage is not a future risk but an entrenched and escalating relaity? Should prevention here be reformulated as harm-limitation or progressive damage reduction?

The court here adopts the due diligence standard familiar from Pulp Mills but it leaves open its exact operational content in climate change mitigation. Due diligence is inherently flexible and must be tested against the circumstances of each case, the degree of risk, and evolving technological and scientific knowledge. The standard of strict liability would not apply in climate obligations and they retain the fault-based due diligence standard. Does the "highest possible ambition" language in the Paris Agreement modify this baseline and tighten the standard of due diligence closer to strict or heightened diligence?

Did 'Common but Differentiated Responsibilities', a treaty-based principle attained the customary law status?