This book was written as a thesis for the Doctorate of Laws, Leiden University. I am most grateful, first of all, to my supervisor, Professor Peter Kooijmans. Throughout my working at this study he allowed me to make use of his wisdom while at the same time affording inspiration and freedom. He never permitted his demanding task as a Judge at the International Court of Justice to stand in the way of discussing my thesis with me for many hours. I also wish to express my profound gratitude to Professor John Dugard, who acted as referent. I benefited very much from his wise suggestions and advice
