We are indebted to Neil Olivier, Diana Nijenhuijzen, Christi Jongepier-Lue and their colleagues in the editorial team at Springer, for their assistance, support and patience regarding the preparation and submission of the manuscript. We would also like to express our gratitude to the contributors to this volume both for their support for our project and for their discerning, stimulating and innovative contributions. We would like, furthermore, to thank the Austrian Cultural Forum, the cultural arm of the Austrian Embassy in London, and Edge Hill University, for the financial support which enabled the ‘Hans Kelsen and the Natural Law Tradition: An International, Interdisciplinary Conference’ to take place. Many of the chapters in this volume are developed from papers first presented at the Conference, hosted at Edge Hill University, UK, in September 2013. In addition to the aforementioned, Peter would like to acknowledge and thank all his friends for their interest and encouragement and to thank his father for his support throughout this book project. Ian would like to express his profound gratitude to family and friends for their insightful comments, cordial forbearance and unfailing kindness. John would like to thank his family, Clare, Joe, Joan and Ken for their support and patience.