My research interests lie in two areas: public international law and the external relations of the European Union.

International law

My work in the field of public international law focuses mainly on the legal framework governing the conduct of military operations. I am particular interested in the legal status of foreign armed forces under international law and have published widely on status of forces agreements and other operational law matters. I maintain close working relationships with the professional community and contribute to the work of several international bodies active in this area. I am the founding director of the Exeter Research Programme in International Law and Military Operations, which provides a focal point for the study of the international legal aspects of contemporary military operations by bringing together experts working in this field at Exeter.

European security and defence

Since 2003, the European Union has acquired an operational capability enabling it to launch and conduct civilian and military crisis management missions abroad. The involvement of the EU in peace support operations raises a range of exciting questions both in relation to its internal law as well as under international law more generally. I have published several papers in leading academic journals and edited volumes on the treaty practice of the EU, its competences in the field of foreign policy and the evolution of the legal instruments of the Common Foreign and Security Policy. I have also contributed chapters to major academic commentaries on the provisions of the Treaty on European Union.