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Priv.-Doz. Dr. Jörg Kammerhofer, LL.M


Short Bio







Jörg Kammerhofer (Mag. iur., Dr. iur., Vienna; LL.M., Cantab; Priv.-Doz., WU Vienna) is a Senior Research Fellow at the University of Freiburg, Germany, and Privatdozent for international law and legal theory at the Vienna University of Economics, Austria. He is a generalist international law scholar and specialises in theory, sources, use of force, dispute settlement, investment law as well as in the theory of law, in particular the Pure Theory of Law. He has published widely on these topics, including his recent monograph International Investment Law and Legal Theory: Expropriation and the Fragmentation of Sources (CUP 2021). He is erstwhile member and chair of the ESIL’s Interest Group on International Legal Theory and Philosophy Co-ordinating Committee. As a member of the Hans Kelsen Research Group he is also involved in publishing the collected works edition of Hans Kelsen’s writings.

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Areas of Research

  • International Law
    • Sources of international law, customary international law, law of treates, interpretation, state responsibility
    • Theory and philosophy of international law
    • Law on the use of force, self-defence, collective security, humanitarian intervention
    • International procedural law/dispute settlement (especially the International Court of Justice)
    • International investment law
  • Jurisprudence/Legal Philosophy
    • Pure Theory of Law/Vienna School of Jurisprudence (Hans Kelsen, Adolf Julius Merkl, Alfred Verdross)
    • Analytical jurisprudence (HLA Hart)
    • Scandinavian legal realism (Alf Ross)


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  •  Books:


The Theory, Practice and Interpretation of Customary International Law

Panos Merkouris, Jörg Kammerhofer, Noora Arajärvi (eds)

Cambridge: Cambridge University Press 2022

ISBN 9781316516898

Although customary international law (CIL) has been central to international law from its inception, it is often misunderstood. This edited volume remedies that problem by tracing the history of CIL and provides an in-depth study of its theory, practice, and interpretation. Its chapters tackle the big questions which surround this source of international law such as: what are the rules that regulate the functioning of CIL as a source of international law? Can CIL be interpreted? Where do lines between identification, interpretation, application, and modification of a rule of CIL lie? Using recent developments, this volume revisits old debates and resolves them by proffering new and innovative solutions. With detailed examples from international and national courts, it places CIL in a range of settings to explain, explore and reflect upon this developing and highly significant field.

Open Access




International Investment Law and Legal Theory: Expropriation and the Fragmentation of Sources

Jörg Kammerhofer

Cambridge: Cambridge University Press 2021

ISBN 9781108839174

Expropriation is a hotly debated issue in international investment law. This is the first study to provide a detailed analysis of its norm-theoretical dimension, setting out the theoretical foundations underlying its understanding in contemporary legal scholarship and practice. Jörg Kammerhofer combines a doctrinal discussion with a theoretical analysis of the structure of the law in this area, undertaking a novel approach that critically re-evaluates existing case-law and writings. His approach critiques the arguments for a single expropriation norm based on custom, interpretation and arbitral precedents within international investment law, drawing also on generalist international legal thought, to show that both cosmopolitan and sovereigntist arguments are largely political, not legal. This innovative work will help scholars to understand the application of theory to investment law and help specialists in the field to improve their arguments.

  • The only book on the law of expropriation in investment law to bring together doctrinal and theoretical arguments
  • Takes a fresh look at the vexed problem of regulatory expropriation
Encourages dialogue between disciplines to re-invigorate generalist international legal scholarship




Die Reine Rechtslehre auf dem Prüfstand/Hans Kelsen’s Pure Theory of Law: Conceptions and Misconceptions

Matthias Jestaedt, Ralf Poscher, Jörg Kammerhofer (eds)

Stuttgart: Steiner Verlag 2020

ISBN 9783515125680

Hans Kelsens Reine Rechtslehre weckt die Aufmerksamkeit der Rechtswissenschaften auch noch nach einem Jahrhundert – in Zuspruch wie in Widerspruch. Sowohl die Aneignungs- als auch die Widerlegungsversuche sind mitunter von Missverständnissen und Ausblendungen geprägt. Während sich die Forschung recht intensiv mit bestimmten Schriften und Konzepten Kelsens auseinandersetzt, haben andere seiner Schriften, beispielsweise unübersetzte Werke, sowie die Werke weiterer wegbereitender Mitglieder der „Wiener rechtstheoretischen Schule“ international wenig Beachtung gefunden. Eine Debatte um die Reine Rechtslehre in und zwischen den unterschiedlichen Kulturen und Traditionen ist daher besonders vielversprechend.

Dieser Band vereint kritische, neutral-analytische und zustimmende Beiträge, die die Reine Rechtslehre aus philosophischer, rechtstheoretischer, ideengeschichtlicher und rechtsdogmatischer Perspektive durchdringen. Die Autorinnen und Autoren analysieren diesen Zugang in einem internationalen und inter- wie intradisziplinären Rahmen; ihnen gelingt es so, die Reine Rechtslehre vorurteilsfrei und offen als Zugang sowie Forschungsfeld zu würdigen und nach der Relevanz, die ihre Thesen heute noch beanspruchen können, zu fragen.




International Legal Positivism in a Post-Modern World

Jörg Kammerhofer, Jean d’Aspremont (eds)

Cambridge: Cambridge University Press 2014 (Paperback 2016)

Hardback ISBN 9781107019263, Paperback ISBN 9781316618479

International Legal Positivism in a Post-Modern World provides fresh perspectives on one of the most important and most controversial families of theoretical approaches to the study and practice of international law. The contributors include leading experts on international legal theory who analyse and criticise positivism as a conceptual framework for international law, explore its relationships with other approaches and apply it to current problems of international law. Is legal positivism relevant to the theory and practice of international law today? Have other answers to the problems of international law and the critique of positivism undermined the positivist project and its narratives? Do modern forms of positivism, inspired largely by the theoretically sophisticated jurisprudential concepts associated with Hans Kelsen and H.L.A. Hart, remain of any relevance for the international lawyer in this 'post-modern' age? The authors provide a wide variety of views and a stimulating debate about this family of approaches.

  • Provides critical and comparative insights into the meaning, use and value of legal positivism in twenty-first-century international legal scholarship
  • Reflects critically on international legal positivism without necessarily espousing any particular theoretical approach

Re-evaluates positivist theoretical, conceptual and methodological moves, and helps readers acquire critical distance from the theoretical mainstream or orthodox theory and methodology of international law


Uncertainty in International Law: A Kelsenian Perspective

Jörg Kammerhofer

Abingdon: Routledge 2010 (Paperback 2012)

Hardback ISBN 9780415577847, Paperback ISBN 9780415813518

Re-engaging with the Pure Theory of Law developed by Hans Kelsen and the other members of the Viennese School of Jurisprudence, this book looks at the causes and manifestations of uncertainty in international law. It considers both epistemological uncertainty as to whether we can accurately perceive norms in international law, and ontological problems which occur inter alia where two or more norms conflict. The book looks at these issues of uncertainty in relation to the foundational doctrines of public international law, including the law of self-defence under the United Nations Charter, customary international law, and the interpretation of treaties.

In viewing international law through the lens of Kelsen’s theory Jörg Kammerhofer demonstrates the importance of the theoretical dimension for the study of international law and offers a critique of the recent trend towards pragmatism and eclecticism in international legal scholarship. The unique aspect of the monograph is that it is the only book to apply the Pure Theory of Law as theoretical approach to international law, rather than simply being a piece of intellectual history describing it.



  • Selected Recent and Forthcoming Publications:
    • ‘Regulatory Expropriation – A New Hope: The Use of Legal Theory for Investment Law’, 24 Journal of World Investment & Trade (2023) – forthcoming
    • ‘Legal Positivism’ in Anne Peters (ed.), Max Planck Encyclopedia of Public International Law (Oxford: Oxford University Press 2023) – forthcoming
    • ‘The Interaction of Doctrine and Theory in (International) Legal Scholarship’ in Pauline Westerman, Kostiantyn Gorobets, Andreas Hadjigeorgiou (eds), Conceptual (De)Constructions of International Law (Cheltenham: Edward Elgar 2022) 9–26
    • ‘Between Pragmatism and Disenchantment: The Theory of CIL after the ILC Project’ in Panos Merkouris, Jörg Kammerhofer, Noora Arajärvi (eds), The Theory, Practice and Interpretation of Customary International Law (Cambridge: CUP 2022) 3–28
    • ‘Fehlerkalkül ohne Fehler. Die Nomomechanik des Derogationsstufenbaus bei IGH Auslegungsurteilen’ in Clemens Jabloner, Thomas Olechowski (eds), Der Stufenbau des Rechts auf dem Prüfstand (Vienna: Manz 2022) 135–171
    • ‘International Legal Positivist Research Methods’ in Rossana Deplano, Nicholas Tsagourias (eds), Research Methods in International Law: A Handbook (Cheltenham: Edward Elgar 2021) 96–111
    • ‘Positivist Approaches and International Adjudication’ in Hélène Ruiz Fabri (ed.), Max Planck Encyclopedia of International Procedural Law (Oxford: Oxford University Press, 2019) [online edition]
    • ‘Die Auslegungsregeln des Völkerrechts: Erkenntnis- oder Entscheidungsleitung?’ in Clemens Jabloner et al. (eds), Scharfsinn im Recht: Liber Amicorum Michael Thaler zum 70. Geburtstag (Vienna: Jan Sramek 2019) 45–61



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