2. the challenge of pluralism

The starting point of Beyond Constitutionalism is that a strict separation between international and domestic law can no longer be justified from an analytical^{Footnote 12} point of view. Inspired by political theorists that have drawn attention to politics beyond the nation state, Krisch suggests that ‘postnational law’ offers a useful framing that ‘overcomes the categorical separation between the spheres [of national and international law], without however merging them fully or necessarily defining the degree of authority their different norms possess’.^{Footnote 13} This new reality leads to new challenges to the legitimacy of both domestic and international law. In the postnational constellation, Krisch argues, domestic law is no longer the sole point of reference for the regulation of internal affairs, which can hamper the pursuit of domestic policy objectives. For international law, the challenge is that its foundation for legitimacy – state consent – is under fire in a world where decisions are increasingly channelled through international institutions and transnational networks.^{Footnote 14}

Krisch posits that there are three possible strategies (or ‘structural visions’) for dealing with the increasing complexity of governance in the postnational world: containment, transfer, or break. ‘Containment’ suggests resistance to change, and a continued emphasis on the importance of national processes as a precondition for international cooperation. He is quick to discard this option as both ‘improbable’ and ‘undesirable on normative terms’.^{Footnote 15} It is improbable in that international governance is – through the delegation to international institutions and the rise of private actors – increasingly less under the direct control of states, and because non-compliance with international norms (another form of exerting control) can be costly. It is also undesirable in that resorting to domestic control processes ultimately fails to include the considerations of those affected beyond their borders, and because they lead to isolated responses that are limited in their effectiveness.

The second strategy, ‘transfer’, refers to transplanting and adapting domestic concepts – such as constitutionalism, democracy and the rule of law – to the international level. Under this model, Krisch singles out calls for a constitutionalism beyond the state, which seek to ‘provide continuity with the domestic constitutionalist tradition by construing an overarching legal framework that determines the relationships of the different levels of law and the distribution of powers among their institutions’.^{Footnote 16}

Krisch’s favoured strategy is to ‘break’ with the traditional, Westphalian model of international law. Although a variety of approaches could be subsumed under such a heading (including, arguably, anarchy), Krisch centres on pluralism, which eschews ideas of an overarching, hierarchical legal framework and instead stresses the productive friction between different legal orders. From here, the book proceeds by contrasting pluralism/‘break’ with constitutionalism/‘transfer’.

The argument for pluralism in Beyond Constitutionalism is carefully constructed. Krisch is fully aware of the inherent and widespread appeal of constitutionalist approaches, and therefore first sets out to critically examine the promises and pitfalls of constitutionalism beyond the state. The appeal of constitutionalism, according to Krisch, resides in that it presents a structural vision that is ‘bound up with the rule of law’.^{Footnote 17} This vision has been put forward first for the European project and later at the global level. The rationale of these suggestions includes the need to keep in check politics – and power – beyond the state. Moreover, advocates are attracted to the structural promise of postnational constitutionalism, which allows for a global hierarchy of rules. Drawing on political theory, Krisch then smoothly guides the reader through a historical background of constitutions and constitutionalism to elucidate the different meanings of the concepts. Whereas constitutions initially were seen as restricting public power, they have evolved to provide the foundation of governments. Yet this foundational constitutionalism ‘would pose high, perhaps radical demands on the existing structure and institutions of postnational governance’.^{Footnote 18} Not only would it require establishing a structure for public international institutions, but it would also need to extend to actors and institutions beyond the state. Moreover, it would need to take into account the widely diverging circumstances in different societies, which are especially pronounced in the global context. Krisch thus points out the inherent tensions between the integrationist tendencies of foundational constitutionalism and the necessary accommodation of cultural and political diversity. This leads Krisch to the interim conclusion that constitutionalism – and ‘transfer’ more broadly – is perhaps not the best model for postnational governance after all.

Therefore, Krisch continues to explore the alternative model – pluralism. He starts by distinguishing between ‘institutional’ and ‘systemic’ pluralism. Given its reliance on overarching norms to resolve interactions (for example, the subsidiarity principle), the former can be seen as akin to some versions of constitutionalism. The latter, however, is rather characterized by ‘decentred management of diversity’,^{Footnote 19} meaning that it is up to individual legal systems to determine their relationships vis-à-vis each other. This variant, Krisch argues, is diametrically opposed to that of foundational constitutionalism.

Like other advocates of legal pluralism before him, Krisch highlights key benefits associated with the non-hierarchical nature of legal pluralism. These include, first of all, a level of flexibility and adaptability that arguably cannot be achieved under any constitutionalist model. Second, Krisch argues that pluralism allows for political contestation, which can be particularly important for challenging hegemons. Third and related to this, pluralism allows for a system of checks and balances in which ‘no single site enjoys ultimate decision-making powers but has to face checks by others that, in some respects, may have equally strong claims to authority’.^{Footnote 20} His final and most fundamental argument in favour of pluralism is one of the main undercurrents: the ideal of ‘public autonomy’ – that is, individuals’ ‘right to determine which polity they want to be governed in and by’^{Footnote 21} – is best reflected in pluralism.

This theoretical exploration is only the first step in Krisch’s multi-layered argument for legal pluralism. Krisch then draws on three pertinent case studies to illustrate the existence and appeal of his pluralist vision: (i) human rights protection in Europe; (ii) individual sanctions imposed by the United Nations (UN) Security Council; and (iii) the trade in products containing genetically modified organisms (GMOs). It is not entirely clear whether these are indeed ‘hard cases’:^{Footnote 22} they are clearly Euro-centric, and they involve mainly ‘hard’ law (as opposed to the informal international lawmaking initiatives discussed below).

Nonetheless, the empirical chapters provide valuable new insights into the ways in which different legal systems interact. In the first case study, Krisch shows how European courts (referring to both the European Court of Human Rights (ECtHR) and the European Court of Justice (ECJ)) and European Union (EU) Member State courts (in France, Germany and the United Kingdom) have taken significant efforts to accommodate each other’s rulings on human rights through judicial dialogue. Importantly, however, he finds that this has happened in the absence of a hierarchical system; on the contrary, courts have insisted on the supremacy of their own legal order.

The case of UN sanctions – brought to the fore by the Kadi judgment of the ECJ in which the Court defied a UN Security Council decision^{Footnote 23} – documents the tension between security concerns and the protection of human rights. Although this points to a drawback of pluralism, Krisch argues that ‘[t]he pluralist structure may ... be seen as a reflection of underlying problems rather than the problem itself’,^{Footnote 24} where domestic interests and values may be at odds with international decisions. In such cases, Krisch posits, pluralism allows for institutional change – if only incremental – and enhances opportunities for contestation ‘that any regime must be interested in receiving in order to ensure its longer term stability’.^{Footnote 25}

The third case study, which involves the nexus of trade and environmental regimes, should be most familiar to readers of this journal. The GMO dispute pitches two major actors – the EU and the United States (US) – against each other. It also concerns the horizontal conflict between two specialized regimes – the Cartagena Protocol on Biosafety^{Footnote 26} and the World Trade Organization’s (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (SPS),^{Footnote 27} which was brought to a head in the EC-Biotech case,^{Footnote 28} as well as the vertical interplay between the WTO, the EU and its Member States. Krisch convincingly argues that pluralism in this case reflects ‘intense social contestation about the locus of authority and the right collective for decision-making on matters of food safety and the environment’.^{Footnote 29} Rather than attributing the lack of international cooperation in this area to institutional fragmentation per se, he offers a cautiously positive assessment that the case shows ‘how much cooperation can be achieved in spite of deep-seated disagreement’.^{Footnote 30} Thus, despite the politicization of the dispute, the regimes in question continued to function relatively normally.

In a final step, Krisch addresses the main criticisms raised against legal pluralism as a normative vision. Drawing on the literature on costs and benefits of hierarchical versus network structures (as well as hard versus soft law), the first criticism – that pluralism leads to unstable international cooperation – is partly acknowledged and partly rebutted. Krisch concedes that the openness of pluralism allows for opportunistic and strategic behaviour by certain (state) actors, but also stresses that it offers a ‘safety valve’ that ‘creates an opening that can be used to signal a need for change as well as the point when the direction of the regime becomes unacceptable to some actors’.^{Footnote 31} The second criticism aimed at pluralism is that it favours the powerful – leading to unfair outcomes. Again, this critique is not rejected entirely, but Krisch underlines that under constitutionalism – where rules favouring the powerful may be cast in stone – the results could be even worse. Pluralism, by contrast, allows for incremental processes of informational and normative change that could challenge the status quo. However, he readily admits that such an argument cuts both ways, as it could favour either the weak or the powerful, and ‘hinges on the direction and desirability of change in postnational politics’.^{Footnote 32}

The third criticism is that pluralism does not fulfil requirements of democratic accountability. Krisch counters that, again, constitutionalism does not fare much better, and that it is too early to tell what postnational democracy will look like. Lastly, Krisch addresses the charge that the rule of law and legal certainty are undermined by a lack of clear relationships between legal systems. Krisch posits that this criticism exaggerates the value of the rule of law vis-à-vis other political values and argues that, while the rule of law is clearly important, it does not require an ‘institutional home’ at the global level.^{Footnote 33} Importantly, Krisch’s plea for postnational pluralism does not equal a call for regulatory chaos and uncertainty. Indeed, in what can be said to be a constitutionalist twist, he closes his argument by proposing ‘interface norms’ to coordinate different legal systems.^{Footnote 34} While the substance of such norms is only briefly discussed, Krisch’s broader point relates back to the all-importance of ‘public autonomy’:

Beyond Constitutionalism offers a thoughtful and thought-provoking defence of global legal pluralism. Krisch presents a careful discussion of the advantages and drawbacks of his vision, and is seemingly one step ahead of his critics every time. Yet, while the book at times attempts to contrast extreme versions of constitutionalism and pluralism, both visions in fact seek to impose some kind of structure, leading to inevitable commonalities. This results in some internal inconsistencies. For instance, early on in the book, Krisch discusses and criticizes scholars who have suggested ordering devices for institutional pluralism;^{Footnote 36} yet it is difficult to see how his proposed ‘interface norms’ are any different from those suggestions.^{Footnote 37} More broadly, therefore, it can be – and has been – questioned whether the pluralist vision suggested by Krisch is indeed as radically different from some versions of constitutionalism.^{Footnote 38}

3. the challenge of informality

The puzzle of Informal International Lawmaking, like that of the first book, is triggered by a multiplication of sites of governance at the global level. While adopting a different approach and tackling different questions, the book is no less ambitious than Krisch’s monograph. The rationale of the book can be found in the need to enhance understanding of, firstly, the emergence and functioning of transnational regulatory activities beyond the state; and, secondly, the possible consequences of such activities in terms of their accountability and effectiveness. To this end, the book first examines the concept of informal international lawmaking, including its legal nature. This is followed by analyses of the impacts of informal international lawmaking and a treatment of the accountability issues to which these impacts give rise. The book concludes with a discussion of how informal international lawmaking plays out at the domestic level.

To frame the concept, the editors introduce the term ‘informal international lawmaking’ (or ‘IN-LAW’), which is defined in Joost Pauwelyn’s introductory chapter:

This broad definition covers a very wide range of initiatives, ranging from high-level political forums, such as the G20, to standard-setting transnational regulatory networks, such as the Kimberley Process Certification Scheme in respect of conflict diamonds. A commonality between these diverse governance arrangements is that international lawyers have had difficulties in classifying them, as is highlighted by Ayelet Berman and Ramses Wessel.^{Footnote 40} The editors make a conscious, but potentially controversial choice in giving this form of cooperation the term ‘lawmaking’. However, Pauwelyn is quick to add that they ‘use the term law in a broader sense including statements or guidelines that may not, strictly speaking, be part of law but merely have legal effects or fit in the context of a broader legal or normative process’ (see also below).^{Footnote 41}

The book adopts an interdisciplinary approach, and several chapters draw on relevant scholarship from the disciplines of international relations and economics. For instance, Liliana Andonova and Manfred Elsig link IN-LAW to principal–agent theory, conceiving of IN-LAW schemes as agents with delegated authority.^{Footnote 42} Adopting a law and economics approach, Stefan Voigt highlights the costs and benefits of informal international lawmaking, and empirically assesses the use of informal instruments by the US.^{Footnote 43} Similarly, various chapters on the accountability of IN-LAW (see below) usefully engage with the political science literature on the subject. The interdisciplinary approach ensures not only that relevant bodies of literature are taken into account, but also forces the editors to be clear about the relevance of the subject matter for international law.

Another contribution of the book is that it helps to distinguish between various conceptual approaches to governance beyond the state that have been put forward by international legal scholars in recent years. These approaches notably include the idea of ‘global administrative law’^{Footnote 44} and the project on the ‘exercise of international public authority’,^{Footnote 45} which share with IN-LAW their focus on ‘how to rein in regulatory administration, whether exercised through formal international organizations, hybrid or private arrangements’.^{Footnote 46} It is perhaps not surprising that the concept of ‘international public authority’ is found to hold certain advantages over those of global administrative law and IN-LAW in the contribution by Philipp Dann – one of the founders of the concept – and Marie von Engelhardt.^{Footnote 47} The more important point, however, is that their chapter, together with Pauwelyn’s introduction,^{Footnote 48} help to avoid the conceptual confusion that may otherwise have inflicted itself upon the novice reader.

Given its subject matter, several of the book’s chapters inevitably engage with the long-standing debate on the legal nature of soft law.^{Footnote 49} In a lengthy chapter, Pauwelyn offers a useful overview of the ‘bright line’ versus ‘grey zone’ schools of thought. Importantly, he suggests distinguishing between ‘law’ and ‘having legal effects’, maintaining that conceptually the bright line school is correct – that is, law needs to be clearly distinguished from non-law – but that non-law may well have legal effects.^{Footnote 50} Reviewing several criteria for distinguishing between law and non-law (form, intent, effect and substance), he illustrates how the universe of international law could contract or expand. Furthermore, by raising the provocative question of whether this whole debate even matters, Pauwelyn highlights a key dilemma for international lawyers: should they fully embrace IN-LAW so as to stay relevant or should they insist on formalism (for example, state consent) to maintain the special identity of international law?^{Footnote 51} In a subsequent chapter, Jean d’Aspremont decidedly opts for the latter, and cautions against the deformalization of criteria for law ascertainment that could result in lawyers seeing international law everywhere. Instead, he argues that international lawyers ‘can zero-in on non-legal phenomena without feeling a need to label them as law’.^{Footnote 52}

The volume’s second main theme concerns the possible consequences of IN-LAW in terms of its accountability and effectiveness. In short, the argument is that if IN-LAW matters, the accountability of IN-LAW matters. The focus on accountability should not be surprising. As Julia Black argues:

Her description matches closely the phenomenon of IN-LAW examined in this volume.

In a thorough and comprehensive examination of the subject, Tim Corthaut and colleagues provide a systematic overview of the various questions raised by the issue of accountability – for example, who should be held accountable, to whom should they be accountable, for what exactly, and using which standards?.^{Footnote 54} Importantly, they show awareness that there is not one type of accountability, and note that there may be trade-offs between the different types (for example, a private business actor involved in informal international lawmaking may find it difficult to be accountable both to its shareholders and to public authorities).^{Footnote 55}

Perhaps not surprisingly, given the diversity of IN-LAW mechanisms, Corthaut and colleagues conclude that ‘[i]t is neither feasible nor desirable to create a one-size-fits-all approach towards the accountability of informal international lawmaking mechanisms’.^{Footnote 56} Still, they put forward suggestions for strengthening the accountability of IN-LAW, emphasizing the opportunities at the domestic level for holding public actors involved in IN-LAW accountable. These domestic accountability mechanisms would need to be complemented by deliberative processes within IN-LAW schemes that would need to be characterized by ‘pluralism, contestation, and openness’;^{Footnote 57} the common ground with Krisch is obvious here. Their conclusions are embraced by Pauwelyn and colleagues in the concluding chapter:

Through this process, the editors argue, it is possible to move from ‘thin state consent’ to ‘thick stakeholder consensus’.^{Footnote 59}

While the accountability of informal international lawmaking is explored in-depth (both by the editors and by various contributors), the conceptualization of IN-LAW’s effectiveness can be argued to be somewhat lacking.^{Footnote 60} Assessing the effectiveness of any international institution – formal or informal – is a highly complex task in which one has to relate the stated or implicit objectives of an institution to observed or anticipated effects. The questions asked by the editors correspond largely with the well-established ‘output-outcome-impact’ distinction in the regime effectiveness literature,^{Footnote 61} but do not acknowledge that examining impact (or problem-solving) effectiveness is a tremendous challenge given the length and complexity of the causal chain between (informal) international law and changes to a particular problem. Moreover, the underlying assumptions that we can clearly identify from the objectives of (informal) international law or unambiguously frame the ‘problem’ at hand can be challenged.^{Footnote 62}

Nevertheless, the book generates valuable insights into the relationship between accountability and effectiveness. Significantly, Corthaut and colleagues find that ‘there is a distinct risk that the multi-actor character of [IN-LAW] mechanisms results in excessive and conflicting accountability mechanisms’,^{Footnote 63} which may lead to trade-offs between the pursuit of accountability and effectiveness.^{Footnote 64}

Although several chapters draw on case studies, the volume consists primarily of conceptual and theoretical contributions.^{Footnote 65} This does not diminish the book’s value, as it allows for different, and at times conflicting, perspectives on the nature and consequences of informal international lawmaking. Indeed, some of the contributions even question the fundamental premises behind the IN-LAW project.^{Footnote 66} But, despite an admirable editing effort by Pauwelyn and colleagues – who have clearly sought to relate the different strands of thought and viewpoints to each other – an inevitable consequence is that some chapters feel somewhat disconnected. An example is the (nonetheless interesting) chapter by Harm Schepel, whose contribution is the only one that centres on private regulators.^{Footnote 67} Moreover, the variety of contributions results in multiple typologies that are not always clearly linked. For instance, Eyal Benvenisti,^{Footnote 68} as well as Andonova and Elsig,^{Footnote 69} offer typologies of IN-LAW mechanisms but the relationship between their typology and the editors’ definition is somewhat muddled. The absence of a rigid analytical framework for the individual chapters also leads to the occasional duplication of arguments with, for example, different chapters discussing the advantages and drawbacks of formal versus informal lawmaking.^{Footnote 70} These minor critical notes are perhaps a reflection of the level of ambition of the book, and are features that generally plague edited volumes. Moreover, the freedom granted to the authors ensures that the reader is presented with different sides of an argument, which arguably outweighs these criticisms.

4. implications for transnational environmental law

Both books reviewed here challenge traditional conceptions of international law: Krisch does so by forcefully arguing that we should embrace legal pluralism at the global level; Pauwelyn and colleagues do so by collecting a number of essays that critically reflect on the role of informality and transnational regulatory processes in international law. In so doing, the books yield insights that can be applied to the field of transnational environmental law.

The phenomena that underlie the books are evident also in the global environmental arena. There are by now over 1,190 international environmental agreements,^{Footnote 71} which are increasingly flanked by a multitude of transnational governance arrangements.^{Footnote 72} Institutional fragmentation has become a common feature of international environmental problems, and debates over the promises and pitfalls of the proliferation of sites of governance are ongoing in areas such as biodiversity, climate change, forestry, genetic resources, protection of the Arctic, and so on.^{Footnote 73} Moreover, several environmental issues are characterized by an increasing number of public and public–private initiatives that could be subsumed under the heading of informal international lawmaking.^{Footnote 74} These include not only the soft law arrangements prominent in international environmental law (such as the 1992 Rio Declaration on Environment and Development),^{Footnote 75} but also a growing number of transnational regulatory initiatives involving public and private actors.^{Footnote 76} Also in the area of global environmental governance, the rise of such initiatives has led to questions concerning accountability (and, more broadly, legitimacy) and effectiveness.^{Footnote 77}

In a way, it is somewhat surprising that – except for the GMO dispute discussed by Krisch and informal networks in climate change governance discussed only tangentially in the volume by Pauwelyn and colleagues – environmental issues do not feature more prominently in both books. Nevertheless, the books’ broader insights provide a useful point of reference for further research in the area of transnational environmental law.

A first inference that can be drawn from Krisch’s book is that calls for global constitutionalism in the realm of international environmental law and governance should be assessed critically.^{Footnote 78} Firstly, they may implicitly or explicitly suggest a primacy of international environmental law over other legal systems. While such a suggestion may sound appealing from the ‘structural bias’^{Footnote 79} of participants in international environmental regimes, it also risks ignoring legitimate objectives pursued through other legal systems.^{Footnote 80} Secondly, where these calls fail to take into account existing cultural and political diversity, they risk becoming obsolete from their inception. While a shift to global environmental constitutionalism may thus not be a panacea, these charges should also not lead to the conclusion that a pluralist or polycentric structure of transnational environmental law is to be preferred by definition.^{Footnote 81} Indeed, as Krisch himself acknowledges, pluralism ‘oscillates between hierarchy and network, but this also means that it shares not only in the benefits but also in the deficits of both’.^{Footnote 82} Thus, centralized and decentralized approaches entail benefits and drawbacks – which are certainly covered by Krisch – that should be carefully assessed on a case-by-case basis. In this regard, the suggestion by Gregory Shaffer – that the virtues and vices of pluralism (as well as those of constitutionalism) depend on the nature of the problem at hand^{Footnote 83} – begs further exploration in the context of transnational environmental law. Shaffer shows how problems involving global public goods – and especially those goods that give rise to collective action problems, such as climate stabilization and ozone layer protection – may, in fact, demand a more centralized approach.^{Footnote 84} Conversely, issues that are more localized, such as adapting to a changing climate^{Footnote 85} or forest governance,^{Footnote 86} may be more amenable to a pluralist, decentralized approach. This recognition calls for further studies that carefully differentiate between the nature of the environmental problem – if problems can be labelled ‘environmental’ in the first place – and analyze the different possible roles of international law.^{Footnote 87}

By coining the notion of ‘postnational’ law, Krisch further draws attention to the changing role of the state. To be sure, it is by no means clear that Krisch is correct that the state no longer plays a central role and that we should move away from the nation state as our central unit of analysis. Moreover, even if one accepts that states are no longer the most important regulators, it is still undeniable that states play a key role, either through regulation at the domestic level or through their participation in intergovernmental processes.^{Footnote 88} Questions on the transformation of the role of the state have also come to the fore in the context of transnational environmental law and governance,^{Footnote 89} where the aforementioned emergence of new actors and mechanisms has cast doubt on the importance of the state in environmental governance. The question, however, is not whether the role of the state is changing, but how it is changing vis-à-vis new forms of governance. In this regard, the contribution by Pollack and Shaffer in the volume by Pauwelyn and colleagues draws attention to the interaction between informal and formal international lawmaking: ‘IN-LAW procedures do not exist, and should not be studied, in splendid isolation’.^{Footnote 90} More precisely, they seek to increase understanding of the conditions under which informal and formal international lawmaking can be considered ‘complementary’ or ‘antagonistic’.^{Footnote 91} This highlights one of the key challenges for future research in transnational environmental law: moving beyond establishing state/non-state and formal/informal dichotomies,^{Footnote 92} and attempting to identify how ‘traditional’ lawmaking and regulation interacts with new forms of governance. In the area of global forest governance, for example, it has been explored how transnational initiatives (the Forest Stewardship Council, for example) could work to support intergovernmental environmental processes.^{Footnote 93} Similarly, it has been suggested that in the area of tackling carbon emissions from deforestation, non-state governance arrangements can work to support international negotiations.^{Footnote 94} In the area of global climate governance, ‘orchestration’ of transnational governance arrangements by international organizations has been raised as a prospective strategy to deal with pluralism.^{Footnote 95} Questions remain, however, about the feasibility of these proposals and, more importantly, the identification of the conditions under which informal and formal approaches could further each other’s objectives based not on individual case studies but on cross-comparisons.

A key theme raised by both books is that of legitimacy and accountability. In this regard, the books raise several points that merit further investigation in the context of transnational environmental law. Firstly, Krisch draws attention to the fact that under circumstances of legal pluralism, assessments of the legitimacy and accountability of individual institutions need to take into account interactions with other regimes. In particular, he suggests that the openness to other legal systems and mutual accommodation means that ‘pluralism can protect itself from overreaching and can tie itself more closely to processes of social change’.^{Footnote 96} Thus, through interactions with others, institutions can seek to enhance their legitimacy, as Krisch underscores, particularly for the case of human rights jurisprudence in various European courts. In addition, it can be argued that institutions should seek to interact with other relevant institutions in order to remain relevant and legitimate also in the eyes of external stakeholders.^{Footnote 97} Kati Kulovesi makes this argument in the context of the WTO, which in her view is experiencing such legitimacy problems with respect to environmental issues.^{Footnote 98} Similar studies could extend these findings, either analytically – by showing how individual environmental institutions have sought to enhance their legitimacy through interactions – or normatively – by arguing how (formal and informal) environmental institutions should seek to improve their legitimacy vis-à-vis external stakeholders.

Secondly, the contributions to Informal International Lawmaking highlight the variety of accountability mechanisms that can be applied to IN-LAW, but the applicability of these mechanisms to specific initiatives in the area of transnational environmental law remains to be tested. Veerle Heyvaert takes a first step, showing how legal administrative standards and good governance principles could be used to assess, and discipline, transnational regulatory power.^{Footnote 99} Similarly, Francesca Spagnuolo examines how standards developed under the heading of global administrative law could be applied to governance beyond the state.^{Footnote 100} Such studies can be extended to both assess and strengthen the accountability of informal international lawmaking in the area of transnational environmental law. However, proposals to strengthen accountability will need to take into account the potential trade-offs with effectiveness, as discussed above. Moreover, it should be remembered that in global governance, there is often not one single type of accountability at play, with the result that strengthening one type of accountability may weaken another type.^{Footnote 101}

Undoubtedly, the books discussed here will raise further questions that will impact upon, and enrich, our analysis of transnational environmental law. By no means do the books close the debate on pluralism and informality in international law, but they do offer scholars interested in these phenomena a concise yet provocative introduction to the scope of the challenge they pose. Given the mission of Transnational Environmental Law to enhance our understanding of these phenomena, I strongly recommend both books to the readers of the journal.