Against Theory?^*

This is not a biography. Rather, Felix Lange focuses on Hermann Mosler’s specific contribution to post-war international law in Germany and Europe. Mosler’s contribution was both methodological and theoretical, as indicated in the book’s title. It took shape, step by step, over the decades of a long life as an academic and jurist. The attempt to reconstruct this side of Mosler’s life, which Felix Lange achieves almost in passing, becomes a prism through which to observe post-war German and international debates on foreign policy, Europe and the post-war world order. Felix Lange thus |combines the history of science and of ideas with legal history and contemporary history. Writing as an international lawyer himself, Lange deploys a particular analytical acuity and writes his book in an excellent style: poignant, diverting, and never jargonized.

That the book assumes a hybrid nature is conceded right at the beginning, when Lange attempts to position his study in between different approaches to writing the history of international law. According to Lange, his study owes much to a wissenschaftsgeschichtlichen approach à la Michael Stolleis; and yet he aspires to integrate other approaches – most notably the contextualizing approach – to overcome the typically employed dichotomy of »life« and »work«. This works well. The reader is thrown right into the great Weimarer Methodenstreit, a fundamental debate that would shape public legal scholarship in interwar Germany. The book opens with the circumstances leading to the establishment of the Kaiser Wilhelm Institute (KWI) for international and public law, the predecessor of the current Max Planck Institute in Heidelberg. In Lange’s narrative, Mosler’s academic life thus starts with the foundation of the KWI some time before it would become an academic home for Mosler himself. Once this backdrop has been drawn, the hero himself may enter the stage. Chapters three and four focus on Mosler’s socialization in a Catholic milieu, his academic apprenticeship at the KWI and on his career after 1945.

The question of Mosler’s attitude towards National Socialism and how (far) he served the regime cannot be avoided. Felix Lange manages to paint an ambivalent and differentiated picture. He shows that Mosler inherited a sort of natural skepticism towards the Nazi ideology because of his upbringing in the Catholic Rhineland. Yet this did not prevent him from pursuing a career as a lawyer under the particular training requirements that had been established by the Nazis. He even joined the SA for a time. On the other hand, he allegedly had close contact with members involved in the attempted coup d’état on 20 July 1944, notably James Graf von Moltke and Berthold von Stauffenberg. Lange emphasizes that all we know about Mosler’s activities at that time derives from his own testimony written with hindsight; the sources thus need to be treated with great caution. What can be established from Mosler’s academic publications and his work at the KWI, though, is that he successfully resisted adopting an ideologically tainted approach to international law.

After 1945, Mosler worked at the law faculties in Bonn and Frankfurt, where he also started his career as a legal and policy advisor. Lange describes the expert opinions that Mosler wrote for the lawyers defending Alfried Krupp in one of the Nuremberg trials. Mosler viewed the trials as a chance for international law, as they confirmed his deeply held conviction that international law consisted of binding and enforceable rules. International law was also a guideline and instrument to respond to Allied policies in occupied Germany, notably to counter Allied demolition plans. Mosler eventually took part in the negotiations for the so-called »Schuman-Plan« with Walter Hallstein and joined the German foreign office. Again, international law was both an instrument and a guide for realizing Germany’s integration into the Western states, a strategy that he vehemently defended at the cost of permanently breaking off collaboration with his East German colleagues. Mosler had been directly involved in establishing Europe’s first supranational organization, the European Coal and Steel Community. He would eventually make organizational questions in international law one of his main research interests as director of the Max Planck Institute for Comparative Public Law and International Law in Heidelberg. That Mosler was not keen on practicing legal studies as l’art pour l’art in the academic ivory tower is evident from his subsequent service as a judge at the European Court of Human Rights and the UN’s International Court of Justice.

By way of these and other examples, Lange demonstrates the cornerstone of Mosler’s methodology, the practice-oriented approach. Mosler’s method proceeded in two steps: firstly, by collecting facts about state practices in an empirical and scientific fashion; secondly, by interpreting the findings from a humanities and jurisprudential point of view. This second step was vital lest the researcher remained in the anemic stage of merely collecting instead of moving on to systematization and theoretical conceptions. And this is how Mosler ultimately derived his grand conception of the international society as a legal community that he outlined during the Cours général at the Académie de droit international in The Hague in 1974. Felix Lange puts this lecture at the heart of the book’s second part and portrays it as a synthesis and outcome of Mosler’s experience as a lawyer, policy |advisor, and judge. Mosler’s key proposition was that states cannot derogate supreme principles of the international legal community because these have constitutional character. At the same time, he emphasized the importance of sovereign states as key actors of this legal community.

Lange presents the lecture as a key text in international legal scholarship and provides us with an impressive commentary that contextualizes the text, traces ideas back to their roots and first discussions, embeds it in the current academic framework, and juxtaposes it with other contemporary ideas about the international order. The chapter on Mosler’s lecture is beautifully framed by two other chapters. The first of these focuses on the alternative and equally prominent approaches by other German jurists at the time, which, however, eventually did not come to yield the same influence. Felix Lange avoids the biographical illusion of hindsight when he acknowledges that, at the time that Mosler was writing, it was by no means clear that his conception and his scholarly work would ultimately exert such influence and win out over alternative approaches. Chapter eleven goes back to examining Mosler’s personality behind the text, his convictions and normative beliefs, and his socialization derived from both his Catholic upbringing and a deep engagement with natural law theories.

Felix Lange has written an impressive account of Mosler’s life and work that is simultaneously a grand tour through international legal scholarship in the post-war world. He has unearthed a great amount of previously unstudied archival material that enables him to analyze and contextualize Mosler’s work at a depth that is eye-opening. His book takes a biographical and historical approach; it earned him the award that carries his protagonist’s name (the Hermann-Mosler-Preis), awarded by the German Society for International Law in 2017. The award recognizes that Lange’s book has the potential to serve as a reference point for both future scholars of modern international law as well as legal historians.