Nuclear non-proliferation continues to dominate political, diplomatic and legal discussions worldwide. Legal issues regarding the non-proliferation of nuclear weapons, the use of nuclear energy for peaceful purposes and nuclear disarmament must be viewed within their relevant context, which is what this book series endeavours to achieve. Volume I1 was widely received with encouraging praise by academics and practitioners alike. This warm reception demonstrates the need for continued efforts to explore such issues further, from an abstract analytical perspective but also from a practical stance. The present volume focuses on verification and compliance. The main body of contributions presented are the results of a research conference on Verification of Nuclear Non-Proliferation Obligations held in Cologne from 13–14 November 2014 in cooperation with the Cologne Institute of International Peace and Security Law. This follows in the tradition of gathering relevant experts to discuss areas pertinent to nuclear weapons, non-proliferation and contemporary international law through a series of Round Table Discussions, which have already led to a comprehensive report on Legal Aspects of Nuclear Disarmament, presented at the most recent conference of the International Law Association (Washington 2014).2 The Cologne event was of major significance for clarifying issues regarding verification problems. It created a better understanding for verification tasks of the IAEA, the CTBTO and EURATOM, providing an instructive interdisciplinary approach to technical possibilities of verification and gaps in current legal regulation which may help to explore implications for treaty design and the implementation of the best practice rules. Moreover, it contributed to greater consensus related to existing legal controversies regarding countermeasures, remedies for wrongful acts and peaceful settlement of disputes.