First Published in 1995. The law of treaties, a central field of international law, was also a central concern for Paul Reuter as a jurist. In close association with Jean Monnet, he made a decisive contribution to the Schuman Plan which led to the treaty instituting the European Coal and Steel Community in 1951. But it was mainly from 1964 onwards, when he became a member of the International Law Commission, that he took an ever-growing part in the development of the law of treaties.