This book project actually begun when I started to work with the Department of Politics, Cardiff University. I must say that writing this book has been a very exciting and stimulating journey – a journey enriched by interesting and thought-provoking conversations shared with my colleagues in the department. I have also had the unique privilege, as an international lawyer, of teaching international law to international relations (IR) students at both undergraduate and postgraduate levels, who, one way or the other, have contributed to my appreciation of areas of international law that are of interest to students of IR.