Intergenerational Equity in International Climate Law as a Legal Criterion for the Interpretation of State Climate Obligations According to the ICJ

This article examines in detail Advisory Opinion No. 32, issued by the International Court of Justice (ICJ) in July 2025. The analysis examines how the decision of the International Court of Justice establishes the principle of intergenerational equity as an interpretative criterion for climate obligations, consolidating specific duties of prevention, due diligence, cooperation, mitigation, and adaptation to the consequences of climate change that directly affect present and future generations. This Opinion also designates the 1.5 °C threshold as a central legal benchmark for assessing States’ due diligence in climate mitigation and adaptation and extends state obligations to the regulation of private actors, characterizing climate protection as an erga omnes duty based on human rights and customary international law. Through a doctrinal and institutional legal method, supported by systematic documentary analysis of treaties, case law and soft-law instruments, this study situates the ICJ’s reasoning within the broader evolution of intergenerational equity and explores its implications for state responsibility and climate litigation. It also analyzes the potential of the Advisory Opinion to foster new institutional mechanisms, such as ombudsmen, fiduciary management mechanisms, and intergenerational impact assessments, to represent future generations in climate governance. The main conclusion is that the Advisory Opinion inaugurates a new stage in global climate governance, in which intergenerational equity ceases to be a purely aspirational vision and instead operates as a binding interpretative standard guiding the interpretation and review of existing climate obligations, rather than serving as an autonomous source of new duties. However, its transformative effect will depend primarily on the political will and institutional capacity of states to implement effective mechanisms.