 He was a member of the International Law Commission between 1962 and 1966, represented Honduras, Spain and Libya in litigation before the International Court of Justice and, as a member of the American delegation, attended the Conference on the preparation of the Vienna Convention on the Law of Treaties.He was also active in numerous international arbitrations as a referee.Briggs was a member of the Institut de Droit International an active in the American Society of International Law, presiding as president from 1959 to 1960.