The present contribution deals with the effect of ASEAN external relations within the ASEAN legal regime and the legal orders of ASEAN Member States. On the face of it, such effects could be expected to be the same as those of international law generally. But we find that ASEAN external agreements are likely to have stronger internal effects within Member States than other international law instruments. Furthermore, they contribute to ASEAN integration and may boost the role of the ASEAN Secretariat.

Our argument is based on an analysis of the obligations of membership in ASEAN and on the principle of ASEAN centrality. Whether compliance with external agreements forms part of the obligations of membership is certainly open to question. We submit that it does, at least with regard to those external agreements that can be read as ‘joint ASEAN agreements’. Furthermore, we draw attention to the role that the ASEAN Secretariat itself may play in developing an answer in that direction. The principle of ASEAN centrality is emphasized in a number of key instruments, including the ASEAN Charter. It is likely to contribute to the stronger impact that ASEAN legal instruments may have on the practice of members’ institutions when compared to instruments of international law generally.

In order to frame the discussion on internal effects, the contribution distinguishes three types of ASEAN external agreements: (i) external agreements of ASEAN as an IO, (ii) plurilateral agreements between state parties that resemble any other international treaty, and (iii) joint ASEAN agreements between state parties, which however credits the fact that state parties on one side of the agreement together form ASEAN.

1. i. For the time being, external agreements of the first type – concluded by ASEAN as an IO alone – do not bind Member States. Such bindingness could only arise from a provision to that effect in the Charter. Agreements of this type may however strengthen the monitoring, facilitating and compliance functions of the Secretariat with respect to the treaty obligations of Member States. Within the context of this first type of agreements, we also discuss the responsibility of ASEAN and the concurrent and subsidiary responsibility of its members. In particular, we submit that members may be indirectly liable for wrongful acts of ASEAN as an IO.