Stefan has a wide-ranging practice in public international law. He has appeared before the International Court of Justice (ICJ), European Court of Human Rights (ECHR) and arbitral tribunals, as well as courts in the United Kingdom, the United States of America and Germany.
His most recent practice has included land and maritime disputes in the South and East China Sea, colonial boundaries in Africa, EU sanctions, state immunity, freedom of expression, the external powers of the EU with regard to the manipulation of sports competitions, and investment protection in situations of civil war and foreign occupation. Stefan has consulted on UN and EU economic sanctions, the financing of terrorism, outer continental shelf delineations, the extraterritorial applications of laws, genocide in international law, the legal status of insurrectional regimes and underwater cultural heritage.
Stefan has also conducted reviews of environmental implications of defence projects and has instructed army, air force and naval officers on international law and the law of the sea.
He is Professor of Public Law, Public International Law and European Union Law, and Director of the Institute of Public International Law at the University of Bonn. He is also a Supernumerary Fellow of St Anne’s College, Oxford.