A Right to a Clean, Healthy and Sustainable Environment

The ICJ’s advisory opinion has been subject to high expectations. At first glance, these expectations appear to have been met. However, upon closer examination, it becomes clear that various statements made by the ICJ remain vague from a human rights perspective. This blog post will explore the human rights dimension of the advisory opinion. Of particular interest is the question of whether human rights should also apply extraterritorially in the context of climate change. This sheds light on the contrasting approaches adopted by the ICJ and the ECtHR in addressing this issue. Going forward, national and international courts will have no choice but to adopt the tone and commitment of this advisory opinion when dealing with issues of climate law.

Harmonizing Approach and Rejecting the Lex Specialis Argument

Having read the ICJ’s opinion on climate change, readers may well ask themselves whether the Court recognized a right to a healthy, clean and sustainable environment. The answer is not straightforward. The ICJ approached a possible response in several steps. First, the ICJ recognized the relationship between the climate protection regime and human rights. The long list of legal regimes that form part of the “most directly relevant applicable law” for the purpose of this advisory opinion in the climate context also includes international human rights guarantees, albeit only in second-to-last place (adv. op. 145 and 172). With this finding, the ICJ is aligning with a discernible trend in international law that recognizes climate change as a matter of human rights concern. This seemingly obvious statement is important because of controversy over the extent to which climate issues should be viewed through the lens of human rights, particularly in the wake of the KlimaSeniorinnen v. Switzerland ruling. The ECtHR was heavily criticised for establishing a link between Article 8 of the ECHR and the climate regime (most prominently, Zahhar 2024.) This approach has now been fully confirmed by the ICJ. The ICJ emphasized “that international human rights law, the climate change treaties and other relevant environmental treaties (…) inform each other. States must therefore take their obligations under international human rights law into account when implementing their obligation under the climate change treaties (…)” (adv. op. 404). This statement is important in three respects: Firstly, it opens legal avenues to human rights bodies and courts. Because we do not have a central body for enforcing climate-related concerns (1), this legal recourse is of paramount importance. Secondly, this statement is crucial for interpreting the obligations under the Paris Agreement. Finally, it is also of great practical relevance for the implementation of judgments by human rights bodies and courts (for example, in the case of the KlimaSeniorinnen).

At this point, the ICJ could have stopped. However, the Court went further, engaging in a second step by recognizing a right to a clean, healthy and sustainable environment, presenting it as “inherent in”, a “precondition” to or “essential” for the effective enjoyment of other human rights (adv. op. 393). The Court, however, does not say whether it recognizes this as a self-standing right. The statements in several separate opinion make it clear that there was no consensus among the judges as to whether this right has achieved the character of an international customary law norm (see sep. op. of Judge Aurescu, 28; sep. op. Judge Bhandari, 3; sep. op. of Judge Charlesworth, 8; declaration of Judge Tladi, 24 seqq.). The content of a right to a healthy, clean and sustainable environment is not fleshed out in the advisory opinion. Judge Charlesworth gives a possible description of the procedural and substantive aspects of this right (sep. op. 9) and links it to the mitigation and adaptation obligation in the climate context (sep. op. 10). It seems obvious that the judges had differing opinions on the content of such a right.

Non-Refoulment for Climate Refugees 

The debate surrounding a possible human right to a healthy environment should not distract observers from another important finding. The ICJ has declared the principle of non-refoulement applicable in the context of climate change (adv. op. 378). Here, too, the ICJ can point to prominent statements in this regard, most notably from the Human Rights Committee (in Teitiota v. New Zealand, 24 October 2019, doc. CCPR/C/127/D/2728/216). From now on, asylum authorities will have to consider non-refoulement when examining asylum applications from climate migrants. However, the ICJ fails to explain to the reader what this principle, which forms part of jus cogens, entails in concreto. Judge Aurescu suggests that climate non-refoulement includes positive obligations to take proactive measures for the prevention of refoulement and to ensure that other rights are respected during the individuals’ stay in the State’s territory (sep. op. 25 in fine). He mentions inter alia a duty to conduct an individualized risk assessment, an obligation to admit those seeking protection and to issues temporary residence permits. At a time when asylum laws are being tightened almost everywhere in the world, these statements are important yet politically controversial. They will require further clarification through case law at both the national and international levels.

Extraterritoriality

Could human rights treaties in the climate context be applied outside the territory of a particular state in question? In this regard, the ICJ very carefully leaves the door open while summarizing the position under international law (adv. op. 395 et seqq.). Apart from omitting any discussion of the ECtHR’s position in Duarte Agostinho (Duarte Agostinho and Others v. Portugal and 32 Others, Grand Chamber, Decision of 9 April 2024, appl. no. 39371/20), the ICJ ultimately left the question unanswered (adv. op. 402). 

The development of case law on extraterritoriality illustrates how international bodies can interpret international law differently. Rather than being a threat to international law, these differences present an opportunity. Undoubtedly, the ECtHR has the strictest case law in this area. In Duarte Agostinho, the ECtHR limited the Convention’s applicability to victims of climate-related breaches of ECHR obligations to individuals within the ECHR Member State’s territorial jurisdiction and it did not deal with possible issues of extraterritorial jurisdiction, such as those which might arise, for instance, in the context of more localised transboundary environmental harm (Duarte Agostinho, § 167). The ECtHR then argued that first, the UNFCCC and Draft Articles 1 and 2 of the Articles on Prevention of Transboundary Harm from Hazardous Activities 

“are documents of a fundamentally different nature than the Convention (…). Secondly, the former are primarily designed to govern the relationships between States, while the Convention comprises more than mere reciprocal engagements between Contracting States and rather creates, over and above a network of mutual, bilateral undertakings, a system of objective human rights obligations (…). Lastly, while the above-mentioned documents refer to the issue of “damage” or “harm” occurring outside the borders of a State, they do not seem to suggest that such “damage” or “harm” would bring any impacted individuals under the jurisdiction of the State from which the damage or harm originated. In fact, these instruments clearly differentiate between the activity causing the damage or harm, which emanates from the jurisdiction of one State, and their effects, which fall within the jurisdiction of another State.” (Duarte Agostinho § 212, all references omitted, emphasis in the original). 

While the ICJ generally attempts to harmonise the various areas of law in its advisory opinion, the ECtHR in Duarte Agostinho makes a strict distinction between the ECHR and the climate regime for questions of jurisdiction. Only time will tell which approach is more convincing.

Wanted: Accuracy, Boldness, and Clarity!

The text of the opinion is unclear in many regards. While it is understandable that the ICJ cannot settle every issue in an opinion down to the last detail, many passages remain vague. Even those involved in the adoption of this opinion complain about the deliberately open wording in some places. Judge Aurescu laments that this Opinion is excessively and unnecessarily cautious and minimalist (sep. op. 1). Judge Nolte likens the Opinion to a Delphic Oracle (declaration of Judge Nolte, 34) and Judge Yusuf states that he is reminded of Alice in Wonderland where Humpty Dumpty says “when I use a word, it means just what I choose it to mean – neither more nor less.” (sep. op. of Judge Yusuf, 6).

Needless to say, we would have liked to see more clarity regarding the role of human rights in the climate context. This applies not only to the content of a possible fundamental right to a clean, healthy and sustainable environment, but also to the principle of non-refoulement under climate law. The ICJ says little about active and passive legal standing in human rights proceedings. Although it refers to future generations on several occasions (adv. op. 157, 273, 313, 373, 377), it does not address how their interests can be asserted in a complaint procedure. The same applies to the vulnerability of certain groups or states. Future proceedings in climate litigation will need to provide clarification at the national and international levels. 

The list of things that the ICJ could clarify may seem long. This is certainly due to the high expectations placed on the ICJ in advance. While certain aspects of the advisory opinion remain vague, from an overall perspective, expectations have largely been met. This must be stressed at this point. It is a remarkable achievement that the ICJ adopted the advisory opinion unanimously – “a rarity in the history of the Court’s advisory jurisprudence” (decl. of Judge Tladi, 2). Although the advisory opinion is not strictly binding, it will undoubtedly influence future legal developments significantly. It sets a tone of commitment, responsibility and alertness for the discussion on the further development in climate law.

End notes

(1) See for a deeper discussion Helen Keller/Viktoriya Gurash/Corina Heri, Do we need a International Climate Court, Heidelberg Journal of International Law, forthcoming September 2025.