On 23 July 2025, the International Court of Justice (ICJ) issued an Advisory Opinion (AO) on State obligations in respect of climate change. It has been called a “landmark” opinion due to its clear confirmation of States’ far-reaching obligations to fight climate change under international law. This post discusses the AO, Switzerland’s position during the proceedings leading to it as well as its potential implications.
Unanimous and unequivocal: The ICJ’s Advisory Opinion
Initiated by a 2023 UN General Assembly resolution, the ICJ recently issued a long-awaited Advisory Opinion on climate following extensive proceedings with a historic amount of contributions by Member States and International Organizations. The judges held unanimously and unequivocally that the climate change treaties (i.e. UNFCCC, Kyoto Protocol and Paris Agreement), additional relevant treaties, customary international law and international human rights law set forth binding obligations for States to protect the climate and other parts of the environment from anthropogenic climate change. The ICJ specified that breaching these obligations may result in legal consequences such as the obligation to cease wrongful actions or omissions, provide assurances of non-repetition or provide full reparation to injured States (find an overview here).
Switzerland’s position during the proceedings
Switzerland was among the well over 100 sponsor countries backing the 2023 resolution and participated in the ICJ proceedings with written and oral contributions (all available here). In doing so, Switzerland demonstrated support for the ICJ and its legitimacy in deciding upon the questions posed.
During the proceedings, Switzerland requested the ICJ to clarify certain elements of international law, such as the customary obligation of due diligence of States to prevent significant harm to the environment outside their jurisdiction and its relationship to the climate change regime. Relatedly, Switzerland argued that the principle of “common but differentiated responsibilities” (CBDR) should be understood as a concept to hold states accountable for past, present and future emissions. The Court largely mirrored these arguments. However, the Court also saw other things somewhat differently. Corina Heri, Assistant Professor at Tilburg University and participant in the ICJ proceedings for the International Union for Conservation of Nature, noted in a conversation with the author of this blog: “One of Switzerland’s central assertions was that there is no methodology under international law for calculating and thereby reviewing a specific State’s greenhouse gas emissions reductions or remaining carbon budget. The ICJ did not technically disagree with this position – but neither did it find that States’ targets are set in a legal vacuum. Instead, it established that national commitments could nonetheless be reviewed against the 1.5℃ temperature threshold.”
What lies ahead for Switzerland?
Despite its non-binding nature, the AO carries significant legal weight because the Court meticulously argued and affirmed that the States’ obligations to fight climate change are, in fact, binding. Therefore, it will likely impact both Swiss international and domestic climate politics.
Firstly, international climate negotiations at COPs will likely be impacted. In the past, many contentious debates have centred around issues now touched upon by the AO (for example “loss and damage”). Negotiating parties – including Switzerland which is active within the ‘Environmental Integrity Group (EIG)’ – may need to adapt their strategies.
Secondly, experts expect an uptick in climate litigation cases due to several clarifications made by the ICJ. “That includes, for example, the possibility of accountability for failures to regulate private actors, the erga omnes (universally binding) nature of mitigation obligations and the recognition that States’ primary target must be to limit warming to 1.5℃. But also, more generally, the applicability of customary and human rights law, which means that States bear binding international obligations even if they withdraw from UN climate treaties like the Paris Agreement”, states Heri. In 2024, the KlimaSeniorinnen and Others v Switzerland case, in which the European Court of Human Rights ruled that the Swiss government violated human rights by failing to adequately address climate change, already caused major discussions in Switzerland. Which leads us to the third potential implication.
Polarization in the domestic debate surrounding climate measures and the role of international courts might increase. While stakeholders and politicians that make fighting climate change a priority welcome the AO, a cantonal section of the far-right Swiss People’s Party issued a statement decrying alleged attacks on Swiss sovereignty due to “climate dictates”. This hardening of fronts could make finding effective solutions to climate change harder, especially considering the country’s direct-democratic political system and the current volatile economic and geopolitical context.
Ultimately, the full extent of the AO’s consequences and whether it truly rings in a new era of climate accountability remains to be seen. A Federal Department of Foreign Affairs spokesperson stated that the opinion will be analysed thoroughly going forward – something to keep an eye out for.
