Custom as the product of successful argumentative campaigns

In spite of the International Law Commission’s reluctance to recognize the direct incidence of non-State actors (NSAs) in the formation of customary international law, this chapter suggests that NSAs could matter in the formation of CIL. After considering international law as an argumentative practice socially constructed, it will be claimed that CIL is the product of successful argumentative campaigns carried out by international lawyers who usually work for States but who could also represent the interests of other actors different from States. Thereby it will be posited that although State lawyers’ views tend to be prioritized when identifying CIL, considerations of lawyers working for NSAs could be also take into account. It will be here initially argued that the two-element approach to CIL reproduced by the International Law Commission is just one possible perspective out of many. In this chapter, a social perspective of CIL will be advocated with a view to defending that the community of international lawyers can possibly give weight to NSAs’ positions in the formation of CIL.