Abstract
The 1970 judgment in *Barcelona Traction, Light and Power Company, Limited (Belgium v. Spain)* is conventionally remembered as the leading authority on diplomatic protection and corporate nationality. This article argues that such a characterization overlooks the judgment's far greater jurisprudential significance. While the Court's holding on shareholder protection has largely receded in practical importance with the emergence of bilateral investment treaties and investor-state dispute settlement, its articulation of obligations *erga omnes* has become one of the foundational principles of contemporary international law. Focusing on the Court's distinction between obligations owed to individual states and those owed "towards the international community as a whole," this article contends that *Barcelona Traction* marked the beginning of a communitarian turn in international legal doctrine, shifting the discipline beyond its traditionally bilateral structure. It traces the subsequent evolution of the *erga omnes* concept through the Court's jurisprudence in *East Timor*, the *Wall* Advisory Opinion, the *Bosnian Genocide* case, *Chagos*, *Belgium v. Senegal*, *The Gambia v. Myanmar*, and Article 48 of the International Law Commission's Articles on Responsibility of States for Internationally Wrongful Acts. The article demonstrates how the dictum in paragraphs 33 and 34, initially unnecessary to the resolution of a corporate dispute, has become the doctrinal basis for community interests, collective standing, and the protection of values regarded as the concern of all states. It further argues that the 2025 Advisory Opinion on the Obligations of States in Respect of Climate Change represents the latest and most consequential application of this principle, confirming that *Barcelona Traction* continues to shape questions of standing, state responsibility, and accountability for collective harms. The article concludes that the judgment's enduring legacy lies not in its corporate law holding but in its transformation of international law into a legal order capable of recognising and protecting the interests of the international community as a whole.