I

As a discipline, one of jurisprudence's central tasks is to identify the features or conditions that distinguish legal rules from non-legal rules (such as morality, or the rules of etiquette). In much contemporary writing, the jurisprudential inquiry is framed as a debate between legal positivism and natural law. While any short summary runs the risk of caricature, for current purposes, it is sufficient to note that natural law theories are marked by their insistence on an essential relationship between law and morality or justice. Under this approach, the validity of a legal norm is dependent, in part, upon the content of that norm; in Saint Augustine's famous dictum, lex iniusta non est lex (unjust law is not law). Legal positivists, in contrast, insist upon the separability of law and morality. Positivists identify certain social conventions, such as ‘rules of recognition’, that establish legality. International law jurisprudence covers much of this conceptual ground, and includes its own enduring debates between and within natural law and positivist traditions, although the terms do not always have identical meanings in the international context. Moreover, given its general lack of coercive enforcement mechanisms, much writing on international law extensively explores compliance issues.

At first glance, Legitimacy and Legality fits squarely within these broad traditions. The text discusses the distinction between law and non-law and devotes considerable attention to the concepts of law, legality, and legal obligation. While the book does not directly focus on the natural law/positive law dispute, its substantial reliance on Fuller inevitably evokes his celebrated debate with HLA Hart, the leading exchange between natural law and positivism in 20th century jurisprudence (Hart Reference Hart1958; Fuller Reference Fuller1958). In addition, Legitimacy and Legality includes a chapter on compliance in which B&T carefully distinguish their theories from those of other prominent scholars, including Thomas Franck, Harold Koh and others. Hence, the volume locates itself within a standard set of jurisprudential debates and presents itself as being in a conceptual dialog with other accounts of international law.

To the extent Legitimacy and Legality presents causal claims that are rooted in the book's thick descriptions of contemporary international law practice,Footnote 1 it might seem that careful empirical observation could confirm or disprove B&T's account. But the sort of conceptual claims and legal theories that B&T advance are different than theories often advanced in the social and physical sciences. In those fields, theories usually attempt to describe the world so that we can better understand the past and predict the future. How will increased emissions of carbon dioxide affect global temperatures? Is drug X effective in stopping the spread of disease Y? Answers to questions like these often involve causal claims that are in principle empirically testable and falsifiable.

However, conceptual claims offered in response to questions like ‘what is law’ or ‘when is law legitimate’ are different. Often, these claims seem designed to delimit categories, and hence are not empirically testable or falsifiable, at least in any obvious way.Footnote 2 Thus, positivists and natural law theorists might disagree over whether the rules promulgated by Nazi Germany or South Africa's apartheid regime are properly considered ‘law’, just as international legal theorists might disagree over the ‘legitimacy’ of, say, UN Security Council sanctions on suspected terrorists or a particular decision rendered by an international court (Wolfram and Volker Reference Wolfram and Volker2008). But disagreements like these do not admit of empirical resolution, and – as Brian Bix points out – often result in theoretical stalemate (Bix Reference Bix1995).Footnote 3 Thus, a different methodological strategy is called for.

II

Fuller's writings suggest such a strategy. Fuller emphasized that law, like many other complex social processes, is a purposive activity. Hence, to understand and evaluate legal arguments, it is often useful to consider the purpose of the particular law or legal system under discussion. Jurisprudence, as well, is a purposive activity. Hence, to evaluate the book's claims, we might ask ‘what is Legitimacy and Legality's purpose?’ To be sure, the authors announce that their ‘principal aim’ is ‘to provide … a new understanding of the importance of legal obligation and of the central role of practice in international law’ (Brunnée and Toope Reference Brunnée and Toope2011). But, as noted, attempting to determine whether, say, B&T, Franck or Koh provides the best account of ‘legal obligation’ or theory of the conditions under which law is ‘legitimate’ is precisely the type of inquiry that empirical inquiry is unable to resolve.

Do the text's case studies suggest another potential purpose? The case studies address the norms governing the use of force, with particular attention to the US decision to invade Iraq; debates over torture, with particular attention to the Bush Administration's use and defense of ‘enhanced interrogation techniques’; and multilateral efforts to construct a climate change regime, notably marked by US withdrawal from the Kyoto process. While each example raises significant doctrinal, institutional, and political issues, these were not the only significant or high-profile international events unfolding as the book was being drafted. Indeed, we can easily imagine a volume explaining contemporary international law addressing other high-visibility and politically salient events such as, for example, ongoing atrocities in Darfur, Security Council sanctions on suspected terrorists, continued tensions over North Korean and Iranian nuclear activities, developments in international criminal law, the accountability of multinational corporations, or the global financial crisis, not to mention theoretical issues that have recently preoccupied international lawyers, such as debates over the fragmentation of international law (International Law Commission 2006; Dunoff Reference Dunoff2011) or the constitutionalization of international law (Dunoff and Trachtman Reference Dunoff and Trachtman2009). No doubt, any account of a subject as vast as international law will inevitably be selective. The point is not to criticize selectivity per se, but to suggest that selectivity necessarily has evaluative dimensions, and therefore that the authors’ choice of fact patterns to emphasize may hint at alternative ways to understand the book's purpose.

Other editorial choices may provide additional clues. Above, I emphasized some of the ways that Legitimacy and Legality fits easily in the genre of jurisprudential writing. However, in several other ways, the book does not fit easily into the jurisprudential genre. Many jurisprudential writings – particularly those that, like Legitimacy and Legality are rooted in current legal practice – devote substantial attention to issues of legal interpretation and legal reasoning. This focus should hardly surprise. As James Crawford and Penny Nevill note, international law is ‘above all a professional and technical practice’ (Crawford and Nevill Reference Crawford and Nevill2011); the interpretation of legal instruments and framing of legal arguments are the characteristic professional and technical activities that lawyers engage in. Moreover, because law in general, and international law in particular, addresses the allocation of decision-making authority, jurisprudence frequently devotes substantial attention to questions of institutional competence, including particularly the role and limits of courts.

Notably, Legitimacy and Legality devotes scant attention to any of these issues. For example, most discussions of the legality of the Iraq invasion focus on debates over the proper interpretation of several key UN Security Council resolutions. Legitimacy and Legality boldly claims that international law was more powerful than the coalition armies, and devotes a chapter to use of force norms, but does not engage in sustained analysis of the relevant Security Council resolutions.Footnote 4 Similarly, most discussions of torture devote substantial attention to the terms of the Torture Convention and related human rights treaties, and to national and international tribunal decisions that distinguish between aggressive interrogations and torture. Legitimacy and Legality discusses the legality of US interrogation practices at length, but devotes at least as much attention to the TV series 24 as it does to relevant treaties or judicial decisions. More broadly, Legitimacy and Legality does not substantially address issues of legal interpretation, institutional competence, or the role of courts. In short, the book is virtually silent regarding many of the key professional tasks and practices that contemporary international lawyers routinely engage in.

III

The conventions of jurisprudence as a genre call for jurisprudential disagreements to be presented as conceptual disagreements. However, as Roger Cotterrell notes, ‘debates in jurisprudence which tend to be portrayed as timeless … are better understood as reflecting specific responses in legal philosophy to pressures, developments, and conditions arising in particular times and places’ (Cotterrell Reference Cotterrell2003, viii). Thus, adhering to the conventions of the genre almost certainly provides only a partial account of the implications of jurisprudential claims, and obscures important historical and political concerns that often drive jurisprudential inquiry.

Consider, for example, Fuller's famous exchange with Hart, widely considered the seminal modern statement of the natural law/positivist debate (Summers Reference Summers1984, 10). Largely forgotten is that both scholars were deeply troubled by the then-vivid example of Nazi-era law. Thus, Fuller defends his jurisprudential approach in instrumental terms: he argues that incorporating moral standards into the criteria for identifying ‘law’ will make it more likely that citizens will resist unjust decrees, such as those promulgated by the Nazi regime. Hart likewise argues on instrumental grounds, claiming that incorporating moral standards into the definition of ‘law’ would make compliance with unjust directives more likely. The deeply instrumental nature of this famous jurisprudential debate,Footnote 5 suggests that ‘giving an account of the nature of law … is not so much a matter of discovery as one of normatively guided construction, with the best account of the nature of law being the one most likely to serve deeper normative goals’ (Schauer Reference Schauer1994). In short, it is often difficult to understand or assess a jurisprudential theory, without a sense of the author's particular quarrel with the world, the discontent that prompted the jurisprudential undertaking in the first place, and the normative outcomes that the author seeks to advance.

If jurisprudential claims presented as analytic truths are, in fact, often deeply rooted in or justified by contextual and contingent political and moral considerations, can we identify the larger political and moral issues raised by B&T's jurisprudence? Legitimacy and Legality largely took shape at a time when the planet's sole remaining superpower had a decidedly uneasy relationship with international legal rules and institutions. A number of high visibility controversies involving the United States raised widespread concerns over whether hegemonic powers threatened the very existence of international law. Among scholars, diplomats, jurists, and citizens who shared this concern, international law was seen as a potential bulwark against a hegemonic power bent on reshaping the international legal order so as to facilitate pursuit of its controversial policy objectives (Alvarez Reference Alvarez2003; Byers and Nolte Reference Byers and Nolte2003; Krisch Reference Krisch2005).

From this perspective, the Iraq invasion, the Bush Administration's efforts to justify harsh interrogations, and the US withdrawal from the Kyoto Protocol, became paradigmatic examples that encapsulate the threat that hegemonic powers pose to international rules and institutions. The critical question – simultaneously jurisprudential, political, and practical – was whether international law and processes could withstand the US pressures to revise legal rules and understandings, and whether these norms and processes could impact US behavior.

The concerns raised by hegemonic powers provide a vantage point from which to understand and evaluate Legitimacy and Legality's claims. Consider, for example, the book's insistence that law be premised on widespread social understandings. This might be taken as a relatively uncontroversial claim about legal systems, particularly those that lack coercive enforcement mechanisms. But note the claim's implications. If true, it means that it is virtually impossible for any single actor unilaterally to create new law. Rather, any agent advocating for change has the difficult task of persuading a highly diverse and diffuse set of international legal actors that a change is both feasible and desirable. The failure to generate a new ‘shared understanding’ means that the proffered new norm will lack legal legitimacy. Moreover, Legitimacy and Legality's inclusive conception of the relevant international audience, including civil society and other non-state actors, further complicates efforts to make new law. Substantially enlarging the number of relevant actors necessarily introduces a set of familiar cooperation and collective action issues, which has the practical effect of privileging the status quo and rendering legal change politically difficult. Finally, the emphasis on communities of practice means that even if a hegemon is able to capture formal lawmaking processes, this ‘positive’ law is merely the start, rather than the conclusion, of a legal dialogue. In short, the ongoing processes and procedures associated with ‘interactional’ international law provide numerous opportunities to offer procedural and substantive obstacles to efforts to revise the law. Thus, both individually and collectively, the features of the international legal system described in Legitimacy and Legality render it difficult for any actor, even a hegemon, to reshape international law to its own will. B&T underscore this political dimension of their jurisprudence in their Symposium contribution: ‘interactional international law's … requirements provide stronger safeguards against political domination and power than a purely formal account of international law … [and] were crucial… in preventing the downgrading, through redefinition, of the anti-torture norm … and in successful resistance to the attempts of norm entrepreneurs to launch a legal doctrine of preventive war’ (Brunnée and Toope Reference Brunnée and Toope2011).

To be sure, the book's line of argument is subject to various lines of critique. For example, some may question whether the examples Legitimacy and Legality foregrounds provide an accurate picture of the key challenges facing contemporary international law. This observation is not intended to minimize the difficulties created by major power recalcitrance, or to suggest that use of force, torture and climate change are unimportant issues. But it is to suggest that by highlighting examples where the actions of a hegemon are both central and problematic, Legitimacy and Legality's case studies may produce a misdiagnosis regarding the central issues facing the international legal order. Particularly in a geopolitical context where significant readjustments leading to an increasingly multipolar world seem well underway, Legitimacy and Legality's lead examples run the risk not only of producing a distorted picture of the critical issues facing the international legal order but of overlooking significant current and emerging challenges.

Moreover, even if hegemonic powers do pose the central challenge to contemporary international law, certain features of interactional international law may be counterproductive. International law's impact is felt in many different ways, including through its use as a language of critique. To label an act – such as a military action or an interrogation technique – as unlawful is to brand it as illegitimate and unacceptable. Ironically, however, while Legitimacy and Legality devotes substantial attention to enhancing international law's legitimacy, the book's conception of international law threatens to undermine law's delegitimizing effect.

B&T emphasize that interactional law arises not from formal promulgation but from ongoing practice. Thus, they write that ‘in international society … congruence (of behavior with rules, a criterion of legality) requires substantial compliance of all participants in a legal system with not only the criteria, but also a continuing practice of legality’ (p. 16, emphasis added). The emphasis on practice (and the preoccupation with the acts of a hegemonic power) suggests that, while it may be hard for one or a small number of actors to create new law, it is likely easier for a small number of actors to undermine old law. As a result, practice that diverges from a formal rule can be understood less as a case of non-compliance than as evidence that the purported rule is not supported by a community of practice and should not properly be considered law. Hence, B&T's account may provide alleged lawbreakers with a powerful argument that the norm being violated is not law at all, and hence of undermining the normative power of a claim of illegality.

Finally, if we understand B&T's theory of interactional international law as, in part, as a reaction to a hegemon's efforts to revise international legal norms, we should also understand that legal and jurisprudential theories do not have fixed normative or political significance. Consider, for example, domestic law notions of racial equality. Dissenting in Plessy vs. Ferguson, where the Supreme Court upheld the notion of ‘separate but equal’, Justice Harlan championed an idea of ‘colorblindness’ that was progressive, perhaps even radical, for its time.Footnote 6 However, more than a century later, conservative opponents of affirmative action embraced the idea of ‘colorblindness’, while progressives critiqued the concept. Borrowing Jack Balkin's terminology, this shift in meaning over time is an example of ‘ideological drift’ (Balkin Reference Balkin1993). Although Balkin was focused on domestic constitutional law theories, ideological drift occurs in international law as well. For example, privileging the notion of sovereign equality in international law in the late 19th and early 20th centuries was associated with progressive notions of self-determination and equality of nations. More recently, progressives have criticized sovereign autonomy for insulating inhumane domestic policies from legal criticism. Similarly, jurisprudential theories of natural law and positivism have, over time, oscillated between associations with progressive reform and with maintaining the status quo.

The phenomenon of ideological drift suggests that jurisprudential claims intended to constrain powerful states, or seen as politically progressive, are likely at some future time to be understood as facilitating actions by powerful states, or as politically conservative. In short, to the extent that the account of interactional international law has political motivations, it is notable that jurisprudential theories do not have any necessary or temporally indifferent political valence.

IV

The discussion above suggests that ‘purpose’ can be a useful touchstone for evaluating jurisprudential claims and briefly hints at some of the political concerns that Legitimacy and Legality's account of international law implicitly addresses. Of course, one might question whether the political implications of B&T's theory are relevant to evaluating the accuracy or usefulness of their account. After all, the accuracy or usefulness of theories concerning, say, the movement of the planets or physical properties of subatomic particles are surely independent of the political or moral implications (if any) of these theories. Is jurisprudence different? To approach this question, let us briefly turn from considering the purpose of international law to considering the purpose of theorizing about international law.

B&T's reliance on Fuller and constructivism problematizes their declaration that Legitimacy and Legality's ‘principal aim’ is to ‘provide international lawyers with a new understanding of the importance of legal obligation and of the central role of practice in international law’. Fuller emphatically rejected the claim that ‘one can take a sharp distinction between simply “reporting” on the existing meaning of a term and improving or clarifying that meaning’.Footnote 7 And constructivists emphasize ‘how, through interaction and communication, actors generate shared knowledge and shared understandings that become the background for subsequent interactions’ (B&T, 13). Thus, the text's methodological commitments suggest that the claim that the book seeks simply to provide a more accurate description of international law is almost certainly too modest.

Indeed, if Legitimacy and Legality's explicit message is ‘that the hard work of international law is never done’ (B&T, 8), perhaps the book's implicit message is that the hard work of international legal theorizing is likewise never done. Constructivism suggests that, just as socially constructed rules of law change over time, so too do socially constructed theories of law. For this reason, we should understand that jurisprudence, no less than law itself, ‘is best viewed as a continuing challenge, rather than as a finished project’ (B&T, 22).

Jurisprudence's unfinished nature suggests that new understandings of international law – including that presented in Legitimacy and Legality – are more created than discovered. Thus, previous efforts to rethink the international legal order were ‘all also projects of reinvention. Each began both as an effort to draw a more accurate map of the global regime and as a project to remake that regime, in part by reimagining and redescribing it’ (Kennedy Reference Kennedy2009). Of course, no one should expect that a single academic work will shift deeply entrenched understandings of international law. However, abstract ideas developed in scholarly writings are one of the tools we use to understand our social world. These ideas are not a given; they are part of a collective exercise in the creation and development of our understanding of law. Thus, what is at stake in debates over the meaning of ‘international law’ and ‘legal obligation’ are the conceptual tools we use to make sense of transnational interactions in our increasingly globalized world.

International law has undergone enormous changes in recent decades. These dramatic changes have generated a sense of heightened disciplinary confusion, anxiety, and disputation, and sparked a period of significant intellectual ferment among international lawyers. These circumstances may provide both the conceptual space and a strategic opportunity to revise our collective understanding of how international law works. These developments may help to explain a motivation behind the recent spate of jurisprudential works, including Legitimacy and Legality, that offer to bring conceptual clarity to a rapidly evolving international legal order.Footnote 8

B&T occasionally hint at the prescriptive nature of their enterprise, such as when they express their desire to ‘provide[ ] concrete guidance for practice that would strengthen international law’, and to ‘outline a framework to assist international lawyers and policymakers in identifying the most promising avenues for normative and institutional development’ (B&T, 5). Notably, it is precisely this prescriptive task that the conventions of jurisprudence as a genre obscure. The detached, analytic language of contemporary jurisprudence frequently elides the moral and political concerns that drive the theory. The prescriptive dimensions of the book's descriptive claims render consideration of the political and moral implications of Legitimacy & Legality's conception of international law not only possible, but also essential (Schauer Reference Schauer2005).