The welcome publication of the Orford and Hoffmann Handbook provides the resources and the occasion for reflection on the state of the art in the theory of international law. A work of comparable scope and authority is unlikely to emerge in the next ten years. In 48 chapters plus an extremely sophisticated and refreshing Introduction by the editors, an impressive range of scholars between them tackle a vast range of subject matter and theoretical considerations. The Handbook is divided into four Parts: ‘Histories’ in which a wide range of global geography is traversed in historical mode; ‘Approaches’ in which theoretical alternatives are directly confronted; ‘Regimes and Doctrines’ in which theoretical dimensions of a range of topics are investigated; and ‘Debates’ in which five particularly obdurate problem areas are investigated. The sheer scale and variety of contributing authors, of topics and of the scholarly resources to which reference is made, are demonstration enough, if any were needed, that the theoretical project in international law is substantial and is occupying the minds of a rising generation of international lawyers around the world as well as the minds of senior, established scholars.

Various questions are raised by the overall subject matter of the Handbook. Does the longstanding distinction between positivist and natural law orientations in international law still have any relevance? Are we doomed to oscillate between those poles in a self-fulfilling prophecy of ‘apology and utopia’? What point have we reached in a critical interrogation of international law? The interrogation of the conceptual basis (as well as the practical effects) of international law has been taking place in a sustained manner for at least 30 years, even if one employs a cautious criterion for relevant contributions (excluding, for example, Hobbes, Rousseau, Kant and Kelsen). Might a certain form of critical approach have become the new mainstream? Relatedly, what is the role of a historical consciousness in articulating a conceptual framework and conceptual contestations in international law? What conceptual challenges and what methodologies have been seriously engaged with? And after over a thousand pages, what is the prevailing mood, the aesthetic, of international jurisprudence as we head for the 2020s?

I return to these questions below. It has been wisely remarkedFootnote ¹ that just as Tolstoy's happy families are all happy in the same way, whereas unhappy families are unhappy each in a unique way, so successfully recognized states are in important senses all the same, whereas ‘failed’ states or non-recognized states are each sui generis. Just so, the most successful chapters in this collection share some common features. They bring together focused attention that is scholarly and well-informed without being obscure, with a sensitivity to the bigger picture. For example, Reut Yael Paz discusses the religious dimension to the School of Salamanca in fine detail but also contextualizes that scholarship within the larger frame of ‘Religion, Secularism, and International Law’. They wear their scholarship with some lightness, as typified by Gerry Simpson. They stimulate questions. Those chapters that are less successful fall short on one or more of these desiderata. Most chapters deliver, at the very least, an informative, thoughtful, and well-argued overview of a particular topic. Some of the contributions that are less successful might be said to be too ambitious in terms of what can be achieved in a chapter length. This is the case for Craven's chapter on ‘Theorizing the Turn to History in International Law’ that opens the book; for Gordon on the role of Natural Law; for D'Aspremont on Sources; and for Hoffmann on ‘International Legalism and International Politics’. With Gordon, as difficult a task as yoking both ‘linear’ and ‘dialectical’ approaches within one chapter calls for more theorization. Much of the chapter seems to be occupied by an account of historical givens which are then subjected to a blanket kind of suspension or critique, whereas surely it is the detail that calls for interrogation, perhaps even ‘deconstruction’. In some cases, there is excessive detail on some background matter such as the biography of Grotius in Van Ittersum's chapter, and the frankly antiquarian details in the chapter by Goodrich.

The longstanding distinction between positivist and natural law orientations towards international legal theory would seem to still have some life in it. Interestingly, it is the chapter expressly addressing positivism that suggests that ‘[a]nti-intellectualism is rampant in international legal scholarship’,Footnote ² and Kammerhofer's incisive and irony-laced overview of this topic points out the poor level of understanding of positivist contributions, both past and present, demonstrated by many contemporary commentators. A supposedly dyed-in-the-wool, positivist international jurisprudence of approximately a century ago, a (dead and white) straw man, is routinely castigated.Footnote ³ Natural law perspectives as such do not receive correspondingly concise and focused treatment. Human rights, often a comfort zone for natural law perspectives, is usefully anatomized by Golder (‘Theorizing Human Rights’) in relation to a turn to pragmatism, or rather to a spectrum of pragmatisms, in that field. The relevance of moral philosophy is investigated by Besson who argues boldly that a moral philosophy of international law has the task of evaluating international law including its normative claims. In other words, moral philosophy of international law is distinct from even ‘the most morality-related legal theories of international law’.Footnote ⁴ Thus, no natural law approach may presuppose its occupancy of the moral high ground vis-à-vis the positivist alternative.

What of the critical tradition? It would appear that instead of what might perhaps have been the case 20 years ago, when arguably a range of critical approaches (feminist, post-Marxist, post-colonialist and so forth) competed with powerful, long-established positivist and natural law traditions, we now face the consequences of the triumph of the critical wave. A coalition of critical schools, subordinating their differences in the interests of solidarity and of generational renewal, have delivered the ‘plague on both their houses’ so that a blended critical orientation is now, it appears, the mainstream. Victors’ justice is now victors’ ‘justice’: everything is in scare-quotes. There are undoubted gains here; reflexivity is preferable to dogma and the expression of angst to the statement ex cathedra. While plurality and the inclusion of minority voices will never entirely undo the effects of domination past, the effort is in some small ways productive as well as honourable. Yet a lingua franca of critique in international jurisprudence threatens to blunt the edge of the resistance. Too often, even in this collection, aspersion substitutes for engagement and received revisionism for rigour. One aspect of the critical mode should be mentioned. As soon as it is recognized that a theory-free account of international law's present or past (or indeed future) is illusory – and whether or not any significant contributor to the discipline has ever thought otherwise – then the status of any purportedly factual substrate becomes problematic. The denial of atrocities is a peculiarly unpleasant and resistant variant, or rather corruption, of perspectivism. Scare-quotes help only to a limited extent. Adopting the nice Biblical metaphor of the optic, the identification of theory-boundedness in the ‘mote’ of a competing account is always easier than its discernment in the ‘beam’ of one's own.

What is perhaps of most concern is the paucity of critical comment on established critical contributions. The new critical mainstream seems a little overprotective of its founders. There is in any case little space in most chapters for extended critique, and the collection is not presented as a handbook of a critical approach as such to international legal theory in which context such critique of critique would be a non-negotiable component. However, it is striking that a mild reservation concerning Antony Anghie's understanding of the European, expressed by Paz, should stand out as it does.Footnote ⁵ Surely neither Anghie nor David Kennedy nor Hilary Charlesworth, for example, would wish to occupy some kind of Pantheon immune from scrutiny and improvement from scholars inspired by their pioneering work. Of these three scholars, only Anghie is a contributor to this collection. Anghie's chapter usefully discusses the role of the imperialist project in constituting international legal theory as we know it. However, it is not clear that it adds precision to use the word ‘peoples’ in phrases such as ‘peoples and scholars of the colonised world’,Footnote ⁶ and ‘[h]ow is international law . . . experienced and understood by peoples who have been systematically disadvantaged . . .’.Footnote ⁷ There is a worrying sense of observance in this kind of expression. ‘Peoples’ are grammatically and ‘ontologically’ on a plane with nations and clans. If precise sense may be made of the claim that peoples as such really ‘experience and understand’ then it would be important to engage with the tricky issue of cultural or national approaches to international law – tricky in part because of racial variants of that approach as in Schmitt. The topic of culturally specific conceptions (of space and time) is discussed by Ruskola in the context of China,Footnote ⁸ but is not widely explored within this collection. This in turn might have facilitated conceptual analysis of group identity and hence of self-determination.

The role of a historical consciousness in articulating a conceptual framework for international law is manifest throughout the collection. The most successful of the contents of Part I (‘Histories’), such as the contributions of Özsu and of von Bernstorff, offer new insights into selected issues at the same time as contextualizing those issues in sophisticated ways. Özsu, for example, highlights the practice of an extraterritorial (‘consular’) exercise of judiciary power by European sovereigns. This was implemented in those foreign states that were deemed to fall neither within the elite club of reciprocal recognition of territorial sovereignties, nor within the barbarian ‘badlands’ where the rule of law was considered to be entirely absent, but awkwardly in-between as with the Ottoman Empire. Özsu's account of these ‘capitulations’ – these ‘gracious concessions’ by the Sultanate – opens up a rich seam of enquiry. Moreover, it exemplifies a sophisticated analysis of the effects of European hegemony, in contrast with a ‘laundered’, Schmittian-lite rendering of ‘us/them’ and of ‘the Other’ that one sometimes encounters. Von Bernstorff reminds us of the boldness and integrity of Kelsen's vision of international law, by which ‘[v]acating the constitutional space in order to fill it with new anti-hegemonic substance now becomes an intelligible project’.Footnote ⁹

‘Capitulations’ were often in the form of bilateral treaties. Thinking about the bread and butter of international law – treaties, customs, expectations, reliance – have we achieved a better understanding of, for example, customary international law with its arcane invocatory formula? This question would usually be thought of as a question about ‘the sources of international law’. The chapter most focused on the question of sources, that of D'Aspremont, is an investigation of the hermeneutics (or perhaps the social ontology) of sources, rather than their deployment. But another author, perhaps, might have got her or his teeth into this vexed, and surely conceptually rich, problem. Perhaps it would be fairer to say that a working knowledge of such questions is presupposed in the likely reader of this Handbook which is, indeed, no introductory text.

In relation to novel conceptual challenges and methodologies, what stands out is the focus on subjectivity and the lived experience of both the practitioners and the beneficiaries (or victims) of international law. This is partly stylistic but after a historical turn there is, perhaps, an experiential turn, fraught with difficulties, even though it gives rise to some important insights and reminders. It is, in some ways, a humanist (re)turn. Both Marx and Foucault, to whom reference is made by several authors in this collection, contributed significantly to the casting of doubt on humanism as a conceptual and ideological framework so that a twenty-first century return to subjectivity appears like a baroque Counter-Reformation. Undoubtedly this new attention to subjective experience, to motivation and perception, calls for more theoretical effort. There is something about ‘formalism’ that seems to stubbornly resist psychologization. As to a prevailing mood, there seems to be an, at times, uneasy alliance between confident revisions of the past and uncertainty over the present functions and the future obligations of international law.

Much more could be said on the virtues of individual contributions to this valuable collection. To conclude with some comments on structure: the division of contributions into four parts is inevitably arbitrary in some cases. Many later chapters in the collection could have been included under the rubric of Part I, ‘Histories’, which already includes 13 chapters, and indeed some of the most informatively historical discussions are to be found in the later parts. Perhaps one of the more successfully innovatory chapters such as Simpson's ‘Something to Do with States’ might have been selected to start the volume. That said, readers will have no difficulty locating contributions in their areas of special interest. More important perhaps, they will find themselves straying across sub-disciplinary boundaries and discovering debates and literatures unknown. This ‘handful’ of interventions establishes a benchmark for some significant time ahead. The challenge now for theorists of international law is to digest and to respond.