The Elusiveness of ‘Interdependent Obligations’ and the Invocation of Responsibility for their Breach

Since the adoption in 2001 of the International Law Commission’s ‘Articles on the Responsibility of States for Internationally Wrongful Acts’, attention has been increasingly drawn to the enforcement by states individually of multilateral obligations. The Commission, for its part, addressed the invocation of responsibility for breaches of such obligations by distinguishing between the respective entitlements of ‘an injured State’, under article 42, and ‘a State other than injured State’, under article 48. In line with this distinction, the existing debate has focused largely on clarifying the entitlement of ‘a State other than an injured State’ to invoke responsibility for breaches of obligations owed erga omnes partes or erga omnes, in accordance with article 48. In contrast, little or no attention is paid in the discussion to ‘interdependent obligations’, which, while deemed to constitute a subset of obligations erga omnes partes, were deliberately placed by the Commission in article 42(b)(ii) as multilateral obligations whose breach was said to injure ‘all the other States to which the obligation is owed’. This article lends necessary clarity to this ‘curious category’ of obligations with a view to the distinction between article 42(b)(ii) and article 48, both of which address breaches of multilateral obligations, but which set out different routes to the invocation of responsibility.