The notion that international organizations are 'special' subjects of international law has been invoked to convey a range of ideas. This is evident in the debates at the International Law Commission concerning the codification and progressive development of the law of treaties and responsibility, where their 'special character' was invoked often and in support of a number of propositions. The chapter addresses three such propositions: (i) that international organizations are different from each other and must thus be treated differently; (ii) that the 'secondary' or 'derivative' subjects of international law must be distinguished from the 'primary' or 'original' subjects; and (iii) that general international law should reflect the fact that international organizations, unlike States, are entrusted with limited competences by their constituent instruments (the 'principle of speciality'). It does so with a view to discussing whether that 'specific character' poses an objection to the analogy between States and international organizations on the international plane.