Introduction
The Inter-American Court of Human Rights’ (IACtHR) Advisory Opinion 32/25 on the Climate Emergency and Human Rights marks one of the most significant recent developments in international human rights law for interpreting state obligations in the context of climate change. The Opinion is ‘sweeping’: it holistically links human rights and environmental law and sets out a ‘blueprint’ for climate governance for states in the Americas. It addresses a wide range of domestic and international policy areas, and unsurprisingly, has attracted substantial scholarly attention – particularly regarding its treatment of new rights and obligations (see here and here), the rights of Nature (see here and here), the obligation not to cause irreversible harm to the climate as a jus cogens norm (see here) and climate-displaced persons (see here).
This blog focuses on a dimension that has so far received comparatively little attention: the Court’s engagement with the concept of sustainable development. The IACtHR connected sustainable development to enforceable obligations under the American Convention on Human Rights (ACHR), thereby attempting to operationalise the concept. In doing so, its approach diverged from that of the International Court of Justice (ICJ) in its 2025 Advisory Opinion on climate change. While the ICJ clarified the legal status of sustainable development as a general principle of law, the IACtHR identified specific obligations relating to sustainable development within the scope of the right to a healthy environment. The remainder of this blog explores the IACtHR’s contributions in this regard against the backdrop of the ICJ’s approach to sustainable development in contentious cases and in its recent Advisory Opinion.
Sustainable Development at the ICJ
The normative quality of the concept of sustainable development has long been contested, and how courts can meaningfully develop it remains uncertain. As Viñuales notes, the term is surrounded by a ‘conceptual fog’, partly due to its deliberate vagueness, making its status and implementation difficult to assess. Some scholars therefore argue that sustainable development lacks the normative force required to qualify as a legal principle. Instead, it represents a political aspiration (see here) or even, as Crawford puts it, ‘a collection, or collocation, of different legal categories.’ Others suggest that while the achievement of sustainable development may not constitute a legally binding obligation, sustainable development nonetheless carries normative value capable of influencing the interpretation, application or evolution of international norms (see here, here and here).
Nearly three decades ago, in Gabcíkovo–Nagymaros (1997), the ICJ referred to sustainable development as a ‘concept’ that captures the need to reconcile economic development with environmental protection (para 140). This required the parties to ‘look afresh’ at the environmental impacts of the project in question. Thirteen years later, in Pulp Mills (2010), the ICJ described sustainable development also minimally, as an ‘international objective’ (para 177).
The ICJ’s 2025 Advisory Opinion on climate change made its normative status clear. The ICJ characterised sustainable development as a general principle of law that evolves both through treaties and independently of them. In the Court’s view, the principle performs a dual function: it guides the interpretation of certain treaties but also contributes to the ‘determination’ of customary international law rules, including the duties of prevention and cooperation (para 147, see here and here). Regarding the duty of prevention, the Opinion suggests that sustainable development helps shape the standard of due diligence for preventing significant climate harm. In the climate change context, this standard is ‘stringent’, requiring a heightened level of vigilance and prevention (para 138). Concerning the duty of cooperation, the ICJ stated that ‘sustainable development is furthered through close and continuous co-operation’ (para 303) and underscored the need for collective climate policy based on equitable burden-sharing and the principle of common but differentiated responsibilities and respective capabilities (para 306).
Even though the ICJ refrained from considering sustainable development as a normatively thick principle, it recognised its interpretative value and its importance in promoting an effective system of climate governance within and between states. As Derler and Andenas observe, the Opinion highlighted ‘the principle’s role as a tool for legal reasoning, particularly in harmonising competing economic and environmental interests to allow for fairness.’ Through this interpretative function, the principle of sustainable development may gradually influence the understanding and application of both treaty-based and customary international rules. By contrast, the IACtHR has pursued a somewhat different path in its treatment of this issue.
Sustainable Development at the IACtHR
Before Advisory Opinion 32/25, the IACtHR had only referred to sustainable development in general terms. In Advisory Opinion 23/17 on The Environment and Human Rights, the Court highlighted the links between environmental protection, sustainable development and human rights merely in general terms (paras 52–55). Later, in La Oroya, it considered that states have an ‘obligation to promote sustainable development’ for the benefit of individuals and communities, referencing the 2030 Agenda for Sustainable Development (para 244).
Through Opinion 32/25, the Court advanced its reasoning. It identified specific obligations related to sustainable development, which inform the scope of the right to a healthy environment protected under Article 26 of the ACHR. According to the Court, states have: first, an immediate and enforceable obligation to adopt a sustainable development strategy in domestic legislation and public policy; second, a progressive obligation to take measures to fulfil this strategy; and third, a duty of non-retrogression, requiring states to refrain from unjustified measures that are ‘blatantly contrary to the aim of advancing sustainable development.’
Through this reasoning, the Court effectively opens the possibility for future cases to scrutinise both a state’s sustainable development strategy – specifically, whether it is sufficiently elaborate or ambitious – and the coherence between the strategy and the state’s implementation measures. The former entails a complex normative assessment of domestic policies in light of national circumstances, whereas the latter is comparatively more straightforward, as it involves assessing the alignment between a state’s declared strategy and the legislative, regulatory and administrative measures adopted to implement it. Therefore, we can discern a clear effort by the Court to contribute to the operationalisation of sustainable development at the domestic level.
Several judges encouraged the Court to go even further. In their concurring opinions in La Oroya and Opinion 32/25, Judges Mudrovitsch, Ferrer Mac-Gregor, and Pérez Manrique argued for the recognition of an enforceable right to sustainable development under Article 26 ACHR, grounded in Articles 30–34 of the OAS Charter. In their view, this right entails balancing and integrating three dimensions: (1) an ecological, involving policies for the protection, conservation and restoration of the environment; (2) an economic, including ‘adaptation of the means of production and consumption’, as well as intergenerational and intra-generational equity; and (2) a social, concerning equal opportunities, decent jobs and poverty eradication (concurring opinion in La Oroya, paras 105-113).
Conclusion
When engaging with the concept of sustainable development, the IACtHR has taken a distinctly different approach from the ICJ. The IACtHR’s contribution locates immediate and progressive obligations relating to sustainable development within the right to a healthy environment, which could allow challenges to states’ legal and policy frameworks in future contentious cases.
How these obligations will be applied in future cases – and what the standard the Court will use to assess compliance – remains to be seen. It will also be important to explore how sustainable development may interact with other rights, such as the rights to food and water. Although the Court acknowledged links between sustainable development and human rights generally (Chapter V, section F.3.2), its analysis focused primarily on the right to a healthy environment. Other rights, however, raise similar environmental, economic and social considerations and may likewise be connected to sustainable development in future jurisprudence. For now, the Advisory Opinion has laid the foundations for a richer and more demanding engagement with sustainable development as a yardstick for assessing the adequacy of state legal and policy frameworks.
Bio
Lisa Mardikian is a Senior Lecturer in Law at Brunel University of London.