Controversial discussion on the state of international law can fairly be called an “academic warhorse,” with international law’s relevance and influence, and its rise and decline, swinging like a pendulum.Footnote ¹ The International Rule of Law: Rise or Decline? accurately captures the current state of this discussion. It is one outcome from a larger research project of the same title, based in Berlin and Potsdam, that aims to facilitate an intense exchange between international lawyers and political scientists from around the globe. The distinguished contributors to this book provide an insightful and critical examination of international law at a time when there is stress and tension arising from attacks by growing populist movements, the denial of the benefits of multilateralism,Footnote ² and state actions challenging the international peace and war order.Footnote ³ The diverse and competing viewpoints and approaches within the collection jointly provide a comprehensive analysis of the topic.

The book contains twenty-two chapters, organized into four parts, providing (1) historical, (2) actor-centred, (3) system-oriented, and (4) justice and legitimacy perspectives on the rise or decline of the international rule of law. The end result may well raise more questions than answers, given the different approaches employed, some of which result in contradictory conclusions, and it is left to the reader to make sense of opposing views on the state of the international rule of law. However, I grant to the editors Heike Krieger, Georg Nolte, and Andreas Zimmermann that the end result flows from a conscious decision to enhance discussion in the field rather than to offer one unambiguous answer. Indeed, the pendulum continues to swing between the various contributors to this book.

In their introduction, Krieger and Nolte explain how the research question has been framed in terms of the relevant period of focus, the substantive scope and boundaries, and the choice of different perspectives. The authors also consider why it is important to ask the question of “rise or decline” and what can be achieved by the different answers given in the book. The introductory chapter outlines the conceptual and theoretical foundations of the book, which serve as a basis for the critical assessment of the current state of international law in the contributions that follow.

Part 1 then begins with a contribution by Jochen von Bernstorff examining whether the period after the 1980s should be characterized as a period of decay. Opposing the widespread assumption that the period following the Cold War has been a prosperous time for the international rule of law, Bernstorff argues that the fundamental notion of the rule of law is “[a]lmost unrecognizable in its original contours … [and] lies in ruins before us.”Footnote ⁴ He sees the central pillars of international law — being economy and wealth and peace and justice — as being foiled by the one-sidedness of international law, which he sees as serving the interests of the economically powerful to the detriment of the less fortunate states and actors. In short, he argues that international law has served to update the economic and political imbalance rooted in imperialism, colonialism, and the Cold War.

The contribution by Anne Peters then illustrates what roles scholars should play in the development of international law and what characterizes good legal scholarship. Rejecting both purely positivist and descriptive approaches, she argues for a realistic approach to legal scholarship — one in which the legal analysis and the proposed legal claims are in accordance with the prevailing economic, political, and social climate. Good legal scholarship, in her view, is prescriptive and, at the same time, practically feasible within its time and circumstances.

A contextual approach to the historical perspective is then proposed by Felix Lange, who is sensitive to the limited potential of historical analysis for predicting the future. This insight is rooted in the diversity of historic narratives available, ranging from the story of progress or great power interest to non-European viewpoints and colonialism. Against this diversity of approaches, Lange favours a quantitative rather than qualitative assessment of rise or decline, adopting a contextual approach that “draws from idealistic, realistic, contributionist, and critical accounts of the history of international law,” suggesting that through the combination of approaches their weak spots may be neutralized.Footnote ⁵ Although generally sympathetic to Lange’s contribution, Andrew Hurrell’s comment then suggests that “strong contextualism is hard to reconcile with the necessity and inevitability of a normative evaluation.”Footnote ⁶ His analysis, however, is coloured by more sceptical notions characterized by the diffusion of power, preferences, ideas, and values. Hurrell, nonetheless, concludes on a positive note that increasing cultural diversity must not lead to cultural or civilizational conflict.

Part 2 of the book presents actor-centred perspectives on the international rule of law, starting with Aniruddha Rajput’s contribution focusing on the impact of the so-called “rising powers” of Brazil, Russia, India, China, and South Africa (BRICS). Rajput analyzes the actions of BRICS on the international stage in a range of areas, including matters of security policy, trade and investment, climate change, and human rights. He finds an increase in their coordination and cooperation, from which he infers their growing impact on international law. The increasing influence of BRICS, in his view, is a sign of qualitative and quantitative progress in the development of international law. Nevertheless, he concludes that the relevant question is not whether international law rises or declines but, rather, whether it is currently in “a state of ‘transition’” under the growing input of BRICS.Footnote ⁷

While he proclaims a bright future and progress for international law through BRICS’ contributions, Simon Chesterman, in his critical comment, presents a contrasting story of their cooperation, unity, and growing impact. Chesterman starts by questioning whether there are enough unifying elements to justify even the existence of a distinct category of BRICS as a relevant state group able to “speak with one voice,” pointing to a lack of organization and consensus. His conclusion, thus, is far more restrained, suggesting that any growing impact of BRICS states might be a sign of the reversal of the development from bilateralism to multilateralism, which ultimately would mean a decline of the international rule of law.

Jean d’Aspremont then argues in his contribution that the very question of whether non-state actors strengthen or weaken international law reveals a liberal school of thought and, moreover, also predetermines the answer. Following a “liberal cosmopolitan” approach, he finds that international law is commonly agreed to apply to non-state actors and that this “inclusiveness” in international law counts as a rise. On the other hand, a “liberal rational” approach is also considered, through which the construction of “otherness” creates a contrast between the state as the realm of order and the non-state actor as a realm of chaos, in which international law is employed to overcome chaos and establish order. Consequentially, d’Aspremont argues that, with either approach, the notion of international law being on the rise is reinforced. In his comment on this contribution, Michael Zürn objects to d’Aspremont’s assumption that the question itself already posits a commitment to liberal theory. Instead, he argues that other schools of thought, such as legal realism or critical legal studies, also discuss the treatment of non-state actors in international law and may come to very different conclusions on whether non-state actors contribute to the field’s rise or decline.

In her contribution considering the legal protection of human rights in an increasingly hostile environment within Europe, Angelika Nussberger focuses on the conventional system of international law and the unsparing criticism of the European Court of Human Rights (ECtHR). Addressing the tension between substantial human rights protection and the discussion of potential trade-offs, Nussberger provides a forthright assessment, making a very valuable contribution. While being generally sympathetic to Nussberger’s account, Geir Ulfstein proposes in his comment that the severe prevailing criticism of the ECtHR is not necessarily informed by rule-of-law concerns, as suggested by Nussberger. Instead, he points to the possibility that there is an even more essential concern about an over-intrusive court, which is exceeding its competencies, with national sovereignty concerns being at the heart of the criticism.

Part 3 of the book provides system-oriented perspectives on the question of the rise or decline of the international rule of law. Against a general compliance trend within legal practice and scholarship, Jeffrey L. Dunoff offers a critical analysis of the utility of compliance with international law as a single indicator for its rise or decline. He claims that an additional assessment of compliance might reinforce the traditional trade-off that international treaties face between a “wide” and “deep” approach, contrasting the high number of participants (wide) with the fostering of ambitious goals (deep). For Dunoff, adding compliance as a factor to the assessment creates a “trilemma,” and he predicts a modified trade-off between the three objectives, whereby, realistically, only two could be realized at once to the detriment of the third. In his comment, Markus Jachtenfuchs presents a less critical view on compliance as being capable of empirical measurement. Although generally supportive of the trilemma concept, he suggests that “preference heterogeneity” is a more meaningful indicator by which to measure the status of the international rule of law than referring to participation (“wideness”).Footnote ⁸

Using international environmental law as an example, Jutta Brunnée then evaluates the capacity of different international rule-making tools (customary law, soft law, and treaties) for the international rule of law. Considering that (environmental) international law is structurally complex rather than simply complicated, Brunnée concludes that the international rule of law is generally “alive and well” and thus fit to develop further with future challenges.Footnote ⁹ Pursuing a broader approach in his comment, Tomer Broude questions the underlying assumptions of Brunnée’s contribution about complexity as a specific feature of international law. He also questions whether the issues discussed are significantly different from preceding discussions of international law crises and whether international law challenges are at all distinct from those of domestic law. His comment critically explores whether the current situation is as exceptional as many contributors seem to suggest or whether this discussion is making a fuss out of the quite normal development of (international) law.

Part 3 concludes with a contribution by Jan Wouters that suggests that, among other factors, populism and elite resistance towards so-called traditional multilateral rule-making contribute to the decline of formal, and to the rise of informal, international law. This development, however, must not generally be considered a loss of achievements; for Wouters, it might well be a great chance to combine both approaches, implement progress, and create a broader toolkit to address modern challenges through international law. In their response, Andreas Zimmermann and Norman Weiss identify the ignorance of international law by populist governments as a significant threat to the international rule of law. For this threat, however, they note that informal international law offers as little relief as formal international law.

Part 4 of the book presents justice and legitimacy perspectives on the international rule of law. It begins with a careful examination of legitimacy claims made by diverse state and non-state actors in the context of the ius contra bellum and ius ad bellum by Thilo Marauhn, who analyzes whether such claims have contributed to a qualitative rise or decline of the international rule of law. Instead of proclaiming a simple answer, he draws an ambiguous and diverse picture of the impact, role, and use of legitimacy claims, depending on their specific circumstances. A comment by Dana Burchardt then provides further insight into the theoretical foundations of legitimacy “as a norm” and “as a legal norm” and how these differences in construction mutually influence the conception and development of the understanding of legitimacy.

In his contribution, Tiyanjana Maluwa employs a differentiated approach to the contestation of value-based norms by questioning what role they can play in assessing the rise or decline of international law. Evaluating two examples of norm contestations — namely, the commitment to non-impunity and the right of intervention as amplified by a responsibility to protect — the author emphasizes the impact of accompanying factors to assess the utility or damage of rule contestations. In their comment, Andrea Liese and Nina Reiners provide a critical approach to the conception, and, thus, the findings, in Maluwa’s contribution. Their insightful conceptual critique of the structure, underlying assumptions, and definitions is valuable in a broader sense and may encourage the reader also to revisit the other contributions critically.

Part 4 then concludes with a contribution by Eyal Benvenisti that questions many of the assumptions employed in the other contributions. His provocative approach focuses on global justice as corrective justice, revealing that the prevailing system of international law may well be a contributor to existing injustice. He not only considers the impact and relationship of access to information and political participation for global justice issues but also emphasizes the chance for global justice lying within the potential use of such data if facilitated by states through the deployment of regulatory means in the global public interest. In the final comment, Maurice Kamto points to the varying conceptions of “justice” in different countries, which may preclude the narrative of “one global justice” as proclaimed by Benvenisti. Further, Kamto suggests that the discussion may also benefit from taking the concept of “global governance” into account.

The core question of whether there has been a rise or decline in the international rule of law remains unanswered, with the goal of the contributions having been to provide different, and even contrary, answers that are derived from a variety of approaches and based on different assumptions. Nonetheless, the book presents a balanced composition of insightful articles and well-founded rationales. It is a valuable contribution to the continuing discussion of the relevance, development, and protection of the international rule of law and serves to enhance the critical reassessment of past research results. Indeed, it is the diversity of perspectives that makes this book a comprehensive account of the current state of the rule of international law.