On April 9 2024, the European Court of Human Rights (ECtHR or ‘the Court’) issued a landmark ruling in the case of Verein KlimaSeniorinnen Schweiz and others v Switzerland, marking its inaugural adjudication on climate change. This decision found a violation of Articles 8 and 6(1) of the European Convention on Human Rights (ECHR), predictably generating significant discourse, with numerous analyses emerging in its wake (for example, see: here, here and here). This commentary specifically aims to highlight the ECtHR’s extensive reference to ‘relevant international law instruments’ within this judgment, arguing that the Court’s methodology aligns with its established practice of incorporating various international human rights law instruments into its decisions.

Through the principle of systemic integration, the ECtHR endeavours to interpret its foundational legal document, the ECHR, in conjunction with developments in human rights at both regional and international levels. As early as the case of Golder v UK in 1975, the ECtHR stated that it considers relevant international law regulations while interpreting the ECHR [35]. However, this approach has occasionally been met with resistance from Member States. For example, Turkey expressed its dissent in the case of Demir and Baykara, criticising the Court’s reliance on instruments that Turkey had not ratified. This tension underscores the complexities of integrating broader international legal frameworks within the ECtHR’s jurisprudence. Similarly, the academic literature highlights that the ECtHR’s substantial reliance on ‘external sources’ have been considered to undermine the Court’s legitimacy. Furthermore, it has been argued that the Court’s use of non-binding materials creates legal uncertainty regarding States’ obligations under the ECHR.

Nevertheless, the case of Verein KlimaSeniorinnen shows that the Court still firmly adopts the principle of systemic integration as a method of treaty interpretation. In the decision, the Court engages with a variety of ‘relevant international materials’ incorporating numerous treaties, resolutions, and agreements regarding climate change [133-231]. These included, but were not limited to, the Aarhus Convention, relevant UN General Assembly Resolutions, Human Rights Council Resolutions, Council of Europe Parliamentary Assembly Resolutions, and reports by UN Rapporteurs. Subsequently, in the section titled ‘comparative law’ [232-272], the ECtHR creates judicial dialogue with domestic cases from several countries, referencing landmark climate change jurisprudence, such as the Neubauer case from Germany, the Urgenda case from the Netherlands.

Systemic integration occurs in a way whereby the Court only quotes the relevant parts of these instruments and judgments without further informing us of the ways they precisely influence the judges’ decisions. The Court typically employs phrasing such as: ‘[t]he relevant parts of the (…) Convention/Resolution/Declaration read as follows’. Therefore, it is difficult to argue the extent to which these instruments and judgments shaped the Court’s decision in Verein KlimaSeniorinnen. However, three issues seem clear: The Court’s interpretation of the ECHR in the light of other relevant instruments helped the Court to identify the positive obligations of Switzerland in the context of climate change regarding the Article 8 of the ECHR. Second, the Court’s approach in Verein KlimaSeniorinnen goes parallel with the climate change jurisprudence quoted in the judgment in terms of protecting the rights of groups of individuals (Neubauer) or non-governmental organisations (Urgenda) – instead of individuals. Thirdly, the decision on the breach of Article 6(1) of the ECHR shows that the procedural rights will play a significant role in the Court’s jurisprudence on climate change. The interpretation of the ECHR in the light of the Aarhus Convention in Verein KlimaSeniorinnen might have strengthened the Court’s unanimous decision of violation of Article 6(1).

Moreover, the ECtHR frequently considers other regional human rights bodies’ constitutional frameworks as ‘relevant international law’. In the Verein KlimaSeniorinnen case too, the Court engaged with the American Convention on Human Rights of 1969 and the African Charter on Human and Peoples’ Rights of 1981. The Court also considered the Inter-American Convention on Protecting the Human Rights of Older Persons as ‘relevant international instrument’ [224]. This convention specifically focuses on the older persons’ right to a healthy environment and identifies the intersectional vulnerabilities of older persons while accessing drinkable water and/or sanitation services. The ECtHR’s recognition and reference of this convention, which is clearly non-binding for Switzerland, serve to strengthen its decision in Verein KlimaSeniorinnen.

Verein KlimaSeniorinnen shows us that the principle of systemic integration is and will remain a pivotal method of treaty interpretation for the Court. Despite the objections from member states, the Court does not differentiate between binding and non-binding law in its interpretation of the ECHR and does not chain itself to member states’ signatures.