The opening words of Martti Koskenniemi's latest opus magnum, “This is not a history of international law,” squarely address the ambivalence with which the book will inevitably be met (p. 1). On the one hand, no book has ever been so eagerly anticipated by those with an interest in the history of international law. Ever since Koskenniemi announced over fifteen years ago that he would delve into the historical antecedents of modern international law between the Middle Ages and the nineteenth century, expectations for the book rose as one fundamental paper after another flowed from the pen of the world's most renowned historian of international law.Footnote ¹ On the other hand, it could never be expected that the author of The Gentle Civilizer of Nations, whose main claim was that international law was only established as an academic discipline in the 1870s, would content himself with rehearsing the familiar line of the authors of the laws of nature and of nations from the Spanish neo-scholastics to Grotius to Vattel, from which, traditional historiography teaches, modern international law is supposed to have sprung.Footnote ²

In his new book, Koskenniemi, recently retired from the University of Helsinki, has indeed done something radically different than follow the thin line of classical jurisprudence of the law of nature and of nations. He has shredded it into small pieces but interlaced those pieces with numerous other threads of private law, constitutional, economic, political, and philosophical thought. What emerges is not a single chronological narrative that connects late-medieval to modern European international legal history, but a colorful tapestry of historical thoughts about the political and legal order of Europe, and its global projection, which derive from a wide range of disciplines and traditions. Inasmuch as the book is considered a history of international law, it is one which embeds that history into a much wider array of Europe's legal and intellectual history and breaks through almost every methodological or epistemological boundary that pre-existing historiography has imposed on itself. In the process, the traditional pantheon of a few dozen canonical authors studied as part of the early-modern prehistory of international law is exploded into a cast of literally hundreds of historical thinkers and actors. These are, as a logical consequence of the geographical and temporal scope of the book, with very few exceptions all male and white (pp. 12–13).

However, the book is much more than a history of international law. It is an attempt to write an integrated constitutional history of the political and legal order of Europe. It is a work of constitutional history as it delves into the foundational questions of political and economic power relations. It explores the functions and organizations of states and relations between the rulers and the ruled. It integrates the level of domestic constitutional law with the state's external projection into the spheres of international, transnational (i.e., commercial), and colonial relations. Koskenniemi declares that the book's central theme is “the use of power in contexts that we would today call international” (p. 1). In this light, the long forays into the domestic constitutional histories of France (Chapters 1, 5, and 6) and Britain (Chapter 8) are ultimately instrumental to the declared telos of the book but receive so much space that, at least for those two countries, one may speak of a balanced, integrated constitutional history. Among the three external dimensions of public authority, the focus lies heavily with commercial and colonial relations whereas traditional issues of “public international law” such as the laws of war and peacemaking and diplomacy receive much less attention.

The book does not apply a traditional method of intellectual legal history, contextual or otherwise. Its purpose is not to present and explain a genealogy of ideas that travel and evolve over time and to relate them to their shifting contexts. In The Gentle Civilizer of Nations, Koskenniemi explored the lives, careers, thought, and writings of some leading international lawyers to analyze the evolution of international law as an academic and practical branch of law between 1870 and 1960. For the almost six centuries covered in To the Uttermost Parts of the Earth, Koskenniemi rejects the claim that a single scholarly tradition evolved over the period and spread over Europe. This is a foundational hypothesis that underlies the structure as well as the methodology of the book.

Koskenniemi has elected a methodological approach that allows exploration of ideas and theories about states’ external power projections from the ground up, that is from the immediate contexts wherein they were used and forged. In order to do this, he decenters ideas and foregrounds their human carriers. He does so through the methodological lenses he labels “legal imagination” and “bricolage.” These terms refer to the daily rhetorical work of lawyers who not only build their arguments through discourses then in use, but also creatively mold legal concepts, doctrines, and theories as they adapt them to the needs of their cases (bricolage). He elevates the common method of legal argumentation into a historiographical theory of “legal imagination,” which considers the process of the historical formation of theories through the work of agents who address questions of power relations by using and reusing existing legal and non-legal concepts, doctrines, theories, and traditions. Through ever-new combinations and adaptions, these agents constantly find new uses for old ideas and forge new ones. The history of thought that emerges is not one of a single tradition—national or international—but a constantly shifting flow of theories that are adapted to changing contemporaneous needs. There is only an intellectual or scholarly “tradition” to the extent that older ideas that exist and persist in the immediate context of a sequence of thinkers are recycled over time.

This bottom-up focus renders the domestic contexts—political, economic, intellectual, and legal—of the book's many characters the point of departure for the discussion of their lives, works, and thought. As Koskenniemi phrases it, “[i]magining [s]tarts at [h]ome” (p. 8). This implies not only that the legal and other intellectual materials that are available to historically situated thinkers are predetermined by their provenance—their education, career, readings, and contemporaries—but also that this “home” is first and foremost a “national” home. In Koskenniemi's narration, the intellectual inspirations and political agendas that motivate thinkers are a product of the governmental and scholarly cultures and the politico-economic agendas of the great budding states of early modern Europe—Spain, the Dutch Republic, France, Britain, and Prussia. Koskenniemi only sparingly mentions the impact of foreign ideas and, even less frequently, the role of transnational intellectual networks. Moreover, the structure of the three Parts of the book on, respectively, France, Britain, and Germany conveys the message that the organization of a state's external power projection is a function of its internal constitutional arrangement.

These methodological and structural choices give the book a theoretical consistency, notwithstanding all the rich diversity of ideas and thoughts that readers encounter. The book's intellectual coherence is rooted in a trio of mutually reinforcing threads that run through the book. The first is the claim that no European-wide academic tradition of the law of nature and of nations existed, but that the international legal imagination took shape in different national contexts. Whereas the alignment of the methodology with this thesis may leave the reader wondering whether the thesis is cause or consequence of the methodology, the book makes a persuasive case that the traditional thin line of the jurisprudence of the law of nature and of nations from Grotius to Vattel, as encapsulated in James Brown Scott's (1866–1943) canonical series of “The Classics of International Law,” never grew into a shared, European scholarly, let alone established, academic tradition.Footnote ³ The richness and variety of other jurisprudential approaches and theories from Britain, France, and Germany that Koskenniemi discusses are indeed resounding refutations thereof. This, however, instills a new relevance to the question what shared concepts, doctrines, theories, and underlying values applied to the works and networks of international diplomacy. What was the common ground where diplomats stood when they met or discussed with one another? While Koskenniemi leaves the practical functioning of law in the international networks of diplomats aside, he has left its students much better armed to address the question to what “the law of nations” as a shared discourse of the actual practitioners of diplomacy, treaty-making and warmaking amounted. The second thread holding To the Uttermost Parts of the Earth together pertains to the distinction, and above all, the constant interactions between sovereignty and property (p. 958). By connecting the legal organization of external and colonial relations with domestic constitutional questions, Koskenniemi uncovers the almost inextricably tied knot between the exercise of “public” jurisdiction and “private” patrimonial rights as the foundation of Old Regime Europe's constitutional arrangement. The shifting interrelations between sovereignty—as the power of lawmaking and law enforcement—and the protection of property rights throughout the centuries, and the breakthrough resulting in the modern distinction between public and private law form the major backbone to this story. This storyline is shaped by the growing significance of a commercial economy and the emergent belief in improvement and progress as the basic purpose of the state from the eighteenth century onward. It also allows Koskenniemi to highlight the essential differences between the countries he covers, in particular France and Britain. The French failure to untie the overlap between public jurisdiction and private rights before the French Revolution prevented it from pursuing an effective commercial and colonial policy that was not dependent on state investment, and therefore could not be sustained under the vicissitudes of both political and economic revolutions. Britain's earlier accommodation between the “merchant interest”—at the latest with the Glorious Revolution (1688)—and the growing power of the state gave it a far more flexible framework for the global projection of its commercial and naval power, while managing the imperial ambitions of other European powers.

While Koskenniemi casts aside the traditional narrative about the canonical writers of the law of nature and of nations as the direct antecedents of modern international law, the jurisprudence of the law of nature and of nations nevertheless forms a third thread throughout the book. The purview of this jurisprudence is, however, far wider than presented in the traditional historiography of international law, as applicable to matters of war and peacemaking and of diplomacy. Koskenniemi treats natural law (jus naturale) and the law of nations (jus gentium) as the semantic chameleons they were, constantly changing their colors and serving different purposes in response to developments over time. This jurisprudence, with its eternal reflections on the relation between divine law, natural law, and the law of nations, reappears as the dominant historical framework to debate the regulation of political, economic, and social relations on both the domestic and international planes, from the perspectives of both the rulers and the ruled. The embedding of the narrow history of public international law, as well as commercial and colonial legal history, into wider constitutional debates, drives Koskenniemi toward exploration of many strands of natural law jurisprudence running from the late-medieval canonists and theologians to the rise of late nineteenth-century legal positivism. Much like Grotius, the leading writers of international, commercial, and colonial relations could not advance their theories with authority outside the context of a general legal theory that used the relations between the divine, the natural, and the human as its point of departure, until the rise of legal positivism in the late nineteenth century. Koskenniemi has faithfully followed the trail of their intellectual reasonings, and thus expanded what began as a history of international law into a constitutional history that has natural law jurisprudence at its center. Koskenniemi's older reading of the law of nations as the flexible middle ground between the ideals of natural law and the exigences of practical lawmaking (powerfully summarized in footnote 107 on page 818) proves a clear spectrum to follow the semantic turns that centuries of theorists applied to the jus gentium. In Koskenniemi's capable hands, the jurisprudence of the law of nature and of nations is not treated as a self-standing category, but rather as a box made of legal concepts, doctrines, and principles that is variably filled with discourses derived from other disciplines and scholarly traditions. These disciplines change over time: from canon and Roman law to theology, political philosophy, history and state sciences; from political economy and natural science to metaphysics and general philosophy. As such, natural law jurisprudence becomes the site for, as Immanuel Kant (1732–1804) put it, the “contest of the faculties” (p. 8).

To the Uttermost Parts of the Earth consists of four major Parts, divided over twelve substantial Chapters, along with a brief introduction and conclusion. The first Part follows the familiar line of the “precursors of Grotius” from traditional international legal historiography. It includes Chapters on the Spanish neo-scholastics, on Alberico Gentili (1552–1608) as an example of humanist jurisprudence, and ends with Grotius. The major innovation in this Part is the inclusion of a Chapter on the late-medieval jus commune of Roman law, canon law, and feudal law. With this Chapter, Koskenniemi demolishes the mental wall that historians of international law have construed between the Middle Ages and the Early Modern Age through their elevation of Grotius, or the Spanish neo-scholastics, as the forebears of international law.Footnote ⁴ Koskenniemi introduces the complex constitutional theories from late-medieval legal scholarship through the lens of their operation by the French King Philip IV (r. 1285–1314) and his lawyers. He uses Philip's conflict with the papacy and his attempts to strengthen royal power in France against feudal elites to unpack key doctrinal discussions by late-medieval Roman lawyers, canon lawyers, and theologians. The Chapter encompasses a lengthy discussion on Saint Thomas Aquinas's (c. 1225–74) legal theory, which forms the background to its re-exploration by the Spanish neo-scholastics in the following Chapter. The choice of Philip IV as the point of entry into the world of the medieval jus commune is appropriate, as it allows exploration of claims of external sovereignty against both medieval universal powers, the emperor and pope, as well as claims of internal jurisdiction against feudal lords. Making Philip's mobilization of Roman law arguments the starting point of the discussion, however, shifts the balance of attention between the two main pillars of the jus commune, Roman and canon law, to the former side. The focus on royal authority keeps the medieval contributions to corporate theory largely unexplored. Nevertheless, as a substantive matter, in under a hundred pages Koskenniemi introduces the reader into the hitherto, to international lawyers largely unknown world of late-medieval legal scholarship that would offer many of the most significant concepts, doctrines, and institutions to the bricoleurs of later ages. In drawing from rich veins of writings on the medieval jus commune, public law, natural rights and property, Koskenniemi breaks through the self-isolation of the historiography of international law.

The Chapter on the Spanish neo-scholastics of the sixteenth and early seventeenth centuries opens with the familiar story of the School of Salamanca's entanglement with justifications for the conquest of the American Indies to wider interventions in contemporary issues of sovereignty and property. These arose not only, or even primarily, from the discoveries in the New World, but from the breakdown of the unity of Christianity, the emergence of a strong royal power in Spain, and the rise of an international commercial and financial market. Koskenniemi sketches how these interventions by Spanish theologians into practical questions of government and property emerged from the Catholic Church's claim to a monopoly over the management of the relation between the eternal soul and God in the internal forum in its fight against Protestantism. As, under Thomistic legal theory, natural law and positive law ultimately derived from God's creation, the upholding of natural and positive law in the external forum fell within the remit of the confessor as a guide to kings and subjects alike. This enticed the Spanish neo-scholastics, many of whom were professors of theology and thus trainers of confessors, to write about economic questions and domestic as well as international governance in a casuistic and probabilistic manner. Only the erasure of this theological context would allow later interpreters such as James Brown Scott or Camilo Barcia Trelles (1888–1977) to promote the neo-scholastics as inventors of the basic principles of modern international law.Footnote ⁵

As other have done before,Footnote ⁶ Koskenniemi singles out Gentili as a civilian lawyer who brought the influence of humanism to bear on the law of nations. He underscores the “Italian” nature of Gentili's jurisprudence as deeply influenced by humanist political and historical writers such as Niccolò Machiavelli (1469–1527) and Francesco Guicciardini (1483–1540). Gentili saw Roman law and historical example as approximative means to regain insights into natural law, the knowledge of which was lost to human beings, and as guidelines to wise statesmanship. The Chapter presents Gentili's inherent pessimism about human ability to know natural law and divine will as part of Italian reason of state thinking, and gives relatively little attention to its foundation in Lutheran political theology. This dimension of Protestantism is a theme, however, of Chapter 11 (801–07).

The first Part, entitled “Towards the Rule of Law,” ends with a Chapter on Grotius. The Dutch polymath functions as a hinge for the overall argument of the book as he is credited with having introduced the idea of human beings as autonomous carriers of subjective, natural rights. In this Chapter, as in a recent article in the same vein,Footnote ⁷ Koskenniemi transcends the decades old debate about the intellectual influences of Grotius and shows him as the genius bricoleur who molded sometimes opposite agendas and different strings of traditions into an ultimately powerfully consistent theory of humanity and rights. Koskenniemi stresses that Grotius's relegation of individual natural right to commutative justice forms his most significant and endurable contribution to European legal theory. This move permitted later thinkers to recreate law as a secular framework of authority over human behavior and opened up a gap between the public world of governance and distributive justice on the one hand, and the private world of commutative property management on the other.

The first Part, which runs almost 350 pages, forms one of the most profound studies in existence of the “history of the law of nations” up to Grotius. It also serves as an introduction to the remaining three Parts of the text. Part II, on Old Regime and Revolutionary France, consists of three Chapters. The first two Chapters focus on the constitution of Old Regime France (Chapter 5) under its most astute managers, Cardinal Richelieu (r. 1624–1642) and Louis XIV (r. 1643/1661–1715) and the economic and political debates unto and through the French Revolution (Chapter 6). In the discussion of the Old Regime constitution of the French monarchy, Koskenniemi dispenses with the old historiography of royal absolutism as the trailblazer for the monopolization of lawmaking under the modern nation-state and aligns with more modern, but by now well-established historiographical trends that underline the patrimonial, contractual, or transactional nature of the state. He foregrounds the venality of offices—in both the civilian and military hierarchies—and the use of monopolies and chartered companies as examples of the mixture of public jurisdiction and private property, next to other methods such as tax farming, seignorial jurisdiction, and forced credit. The dynastic international, commercial, and colonial policies of seventeenth-century France thus appear as extensions of a patrimonial power conglomerate of royal dynasty and elite families. This formed the very fabric of the state wherein the royal government acted as the ultimate mediator of the rights of estates and families. Against this backdrop, the constitutional and economic debates of the Enlightenment, increasingly framed in secular natural law discourses, became attempts to define a national public interest against the many private interests that were enshrined in the framework of the transactional state. They also aimed to adjust France to a national and international commercial context wherein mercantilist competition and dynastic ambitions clashed with the desire for free and peaceful commerce. In this narrative, the French Revolution (1799–1804), by making the nation into the bedrock of the state, destroyed the transactional constitution of France and achieved the “[g]reat [d]emarcation” of sovereignty and property as an implementation of the principles of natural liberty and equality, under the very aegis of commutative justice.Footnote ⁸ It enshrined the defense of property as the nation-state's primary domestic, international, and colonial purpose. This was reflected in the Revolutionary period's main French scholarly text on the law of nations, that of Joseph-Mathias Gérard de Rayneval (1736–1812). Chapter 7 covers the colonial policies of the seventeenth and eighteenth centuries. French colonization in Northern America and the Caribbean, and its role in the transatlantic slave trade, which were largely state-driven affairs through the use of chartered, often state-sponsored companies. Its major designers, Richelieu and Jean-Baptiste Colbert (1619–1683), saw colonization as an extension of their European mercantilist policies with the purpose of enhancing the fiscal basis of the state. Although some revolutionary factions urged the application of natural rights of liberty and equality to the Caribbean colonies, under Napoleon Bonaparte (1769–1821) the French state reverted to its European instrumentalization of the New World and reintroduced slavery. Revolution ultimately came to the French colonies through the rebellion in Haiti.

The three Chapters of the third Part discuss the British empire between the sixteenth and nineteenth centuries. This Part moves from the domestic constitutional debate (Chapter 8 and 9) over Britain's commercial and maritime expansion (Chapter 9) to its global imperial extension (Chapter 10). The first two Chapters analyze England's constitutional history from the Late Middle Ages onward. The clashes between royal monarchy and economic elites represented in Parliament, which came to a highpoint under the Stuarts in the seventeenth century, resulted in the control over the state by the merchant interest. By the late seventeenth century, after the Glorious Revolution, the “[m]ercantile [s]tate” (pp. 630–33) was largely in place. The propertied classes’ victory over attempts at royal absolutism by the Stuarts guaranteed the inviolability of property and created the conditions for the development of a commercial, imperial, and capitalist economy, projected and protected by the law, bureaucracy, and the military apparatus of a state. In constitutional terms, the conflict was fought over the extent of the royal prerogative against the limiting powers of Parliament and common law courts. In the theories of defenders of the common law such as Sir Edward Coke (1552–1634), natural law and the law of nations were subsumed under the common law and the interpretation of it by the common law courts. This made the common law into a legal instrument for commercial, imperial, and colonial expansion. The common law became a framework of the interpretation of natural law and the law of nations, and the guardian of its own distinction between the rules as well as the people that were included or excluded from its remit. This constitutional framework proved conducive to the establishment of a global empire under the liberal and utilitarian political and economic theories of the Scottish and English Enlightenments. It was an empire based on the rights of “life, liberty, and property” at home, free trade on and over the world's oceans, and colonial expropriation under the utilitarian doctrines of “improvement.”

In the fourth Part, Koskenniemi returns to the more familiar terrain of the German tradition of the law of nature and of nations. As the author has stated before, inasmuch as the jus naturae et gentium formed an established academic discipline, it was a German one and a Protestant one at that.Footnote ⁹ This allows the author to follow a more chronological line of intellectual development in Chapter 11, which covers the sixteenth century to the publication of Emer de Vattel's (1714–1767) treatise on the law of nations in 1758. Koskenniemi explains the growth of a vibrant academic discipline of the law of nations as a logical extension of debates on the relative jurisdictions of the imperial institutions and the estates within the Holy Roman Empire during the decades before and after the Peace of Westphalia (1648). The discipline fed off the reception of Grotius's main treatise on the laws of war and peace. In the German tradition of the law of nations and of nature, Samuel Pufendorf (1632–1694) is credited for having turned jurisprudence toward the organization and functioning of the state through the empirical study of society, law and history (p. 829).Footnote ¹⁰ The law of nations thus became part of a wider array of disciplines in the fields of public law and statecraft. Chapter 12 covers the intellectual history of natural jurisprudence of the Enlightenment up to the works of Georg Wilhelm Hegel (1770–1831). Koskenniemi identifies four variations of natural law discourse: the empirical political science of Johann Jacob Schmauss (1690–1757) and Gottfried Achenwall (1719–72) who continued the line of the science of statecraft (Staatsklugheit) from their stronghold at the University of Göttingen; the economic discourse that is represented through the work of Johann Heinrich Gottlob Justi (1717–1771); the philosophy of Immanuel Kant; and the tradition of practical diplomacy as law of nations in the works of Georg Friedrich von Martens (1756–1821). The final pages of the Chapter are devoted to Hegel. His thought is presented as a synthesis of Enlightenment traditions, which elevated the modern state into the carrier of human freedom and the condition for human progress through the pursuit of private interests (pp. 941–42), domestically and internationally. Thus, Hegel set the scene for the nineteenth-century German literature on the law of nations as external law of the state. Some brief references to later nineteenth-century writers, in particular Robert von Mohl (1799–1875) and Johann Caspar Bluntschli (1808–1881), in the Epilogue of the book throws a line to the event at Ghent in 1873, which formed the starting point of The Gentle Civilizer of Nations.

To the Uttermost Parts of the Earth is the result of its author's thorough exploration of more than half a millennium of writings on the history of European order and its global expansion. Two decades ago, in 2002, Koskenniemi produced with The Gentle Civilizer of Nations a book that deeply impacted the view of international lawyers and historians alike on the grand narrative of international law's history, and on its methodologies. In this volume, and in his papers over the past fifteen years, Koskenniemi has broken through major epistemological boundaries associated with prevailing views on the history of international law since their first articulations around the turn of the twentieth century, including the field's self-isolation from the Middle Ages, the division between public and private law, and the dualist separation of the domestic and international legal spheres. While this project began as an exploration of the prehistory of international law, Koskenniemi has embedded and expanded this theme into so many different layers of historical jurisprudence that it has turned into something radically different, and far grander, than “a history of international law.” With this book, the intellectual trailblazer of the “turn to history” among international lawyers has surprised again. He has opened a vision on a new disciplinary approach within legal history which may be called “the constitutional history of European order.”

Through the lens of “legal imagination” and “bricolage” and driven by an intellectual rigor to do justice to both primary sources and wide swaths of secondary literature, Koskenniemi has delivered a work that for its combination of encyclopedic breadth with analytical depth makes one recall the greatest public law historians of the late twentieth century such as Walter Ullmann (1910–1983), Harold Berman (1918–2007), or Brian Tierney (1922–2019). This lens, which comes with a constant focus on the interface between the flow of ideas, biography, and the pragmatic dictates of shifting political contexts, has allowed the author to transcend the battle lines of the recent “contest of the faculties” within the field of the historiography of international law between “dogmatic law” and “contextual history.”Footnote ¹¹ The book is proof in itself that the contextual reading of classical texts may serve to strengthen the foundations of intellectual or dogmatic legal histories over long stretches of time.

The result confronts the reader with a myriad of characters and ideas, and is at times somewhat bewildering. While the reading of any single Chapter will be rewarding because of the sharp insights Koskenniemi throws around on almost any page—with some of his main interventions sometimes nicely tucked away in a footnote—the reader should not be daunted by the book's size nor shy away from reading it cover to cover. She will then discover that the book is a veritable trove of intellectual pleasure, full of ideas and written in a remarkably accessible style. She will also discover, and maybe deplore, that aside from the brief introduction and conclusion, and altogether very rare discursive interventions in between, Koskenniemi gives relatively little guidance in terms of making explicit connections between the authors, the ideas, the Chapters, and the Parts. He leaves the reader to think for herself. In doing so, he has issued an open invitation for further research and reflection on some grand topics that spring to mind, such as the genealogies of ideas, the comparison of national or regional approaches, the transnational debates between scholars from different countries, the role of shared ideas and values in international networks of diplomats and economic elites, and most ambitiously, a global approach to constitutional history. With this book, Koskenniemi has pioneered an integrated constitutional history of international order. He has set a high bar for those who want to follow on this path, but he has also offered strong foundations to build on.