His main area of expertise is constitutional theory. He has published extensively on the constitutional dimension of legal order at sub-state, state, supranational and international levels. He has also published at length on the relationship between security, legal order and political community. He maintains a more general interest in broader questions of legal theory as well as in various substantive dimensions of UK and EU public law.

Previously he taught public law at Edinburgh for ten years (1986-96), was Professor of Legal and Constitutional Theory at the University of Aberdeen (1996-2000), and, most recently, was Professor of European Law at the European University Institute in Florence (2000-8), where he was also the first Dean of Studies (2002-5).

He has also held various visiting appointments - including Visiting Professor, Department of Philosophy, University of Tilburg, Netherlands (2000); Visiting Professor of Law, University of Columbia, NY(2005); Eugene Einaudi Chair of European Studies, University of Cornell (2007); Distinguished Visiting Professor of Law, University of Toronto (2007). and Global Professor of Law, New York University (2011-12)

Professor Walker's inaugural lecture, entitled "Out of Place and Out of Time: Law's Fading Co-ordinates", was delivered on the 18th November 2008. You can listen to it from the Blogs and Podcasts section of the School website.

In December 2008 Professor Walker was asked by the Scottish Government to conduct an independent review of final appellate jurisdiction in the Scottish legal system. His final Report, submitted in January 2010, can be found at:

This book develops and defends an original argument concerning the importance and value of security as a good, and the virtue and necessity of the democratic state in fostering and sustaining that good. It travels widely over debates in social and political theory, sociology, criminology, law and international security studies.

International co-operation and criminal law enforcement have become a centrally important policy issue for Europe in the 1990s. This book examines all of the major empirical and theoretical issues associated with the emerging pattern of co-operation, including the harmonization of criminal law and criminal procedures, law enforcement strategies, police organization and discipline, and the politics of immigration and civil liberties.

Public law has been conceived in many different ways, sometimes overlapping, often conflicting. However in recent years a common theme running through the discussions of public law is one of loss. What function and future can public law have in this rapidly transforming landscape, where globalized states and supranational institutions have ever-increasing importance?

The contributions to this volume take stock of the idea, concepts, and values of public law as it has developed alongside the growth of the modern state, and assess its continued usefulness as a distinct area of legal inquiry and normativity in light of various historical trends and contemporary pressures affecting the global configuration of law in general.

Divided into three parts, the first provides a conceptual, philosophical, and historical understanding of the nature of public law, the nature of private law and the relationship between the public, the private, and the concept of law. The second part focuses on the domains, values, and functions of public law in contemporary (state) legal practice, as seen, in part, through its relationship with private domains, values, and functions. The final part engages with the new legal scholarship on global transformation, analysing the changes in public law at the national level, including the new forms of interpenetration of public and private in the market state, as well as exploring the ubiquitous use of public law values and concepts beyond the state.

Tis volume started as a series of papers to mark the contribution of the late Sir Neil MacCormick and to celebrate his scholarship and life.

This book sets out to examine some of the key features of what we describe as the paradox of constitutionalism: whether those who have the authority to make a constitution - the 'constituent power' - can do so without effectively surrendering that authority to the institutional sites of power 'constituted' by the constitutional form they enact. In particular, is the constituent power exhausted in the single constitutive act or does it retain a presence, acting as critical check on the constitutional operating system and/or an alternative source of authority to be invoked in moments of crisis? These questions have been debated both in different national contexts and at the level of constitutional theory, and these debates are acknowledged and developed in the first two sections of the book.

Part I includes chapters on how the question of constituent power has been treated in the constitutional histories of USA, France, UK and Germany, while Part II examines at the question of constituent power from the perspective of both liberal and non-liberal theories of the state and legal order. The essays in Part III consider the operation of constitutionalism with respect to a series of contemporary challenges to the state, including those from popular movements below the level of the state and challenges from the supranational and international levels, and they analyse how the puzzles associated with the question of constituent power are played out in these increasingly important settings

This volume brings together a collection of classic and contemporary texts which engage with the core problem of sovereignty from the perspective of various legal and law-related sub-disciplines: legal history and theory, constitutional law, international law and relations and EU law. Many of the highlights from the intense debates about the continuing relevance or otherwise of the internal sovereignty of national legal orders and the external sovereignty of states in a rapidly- globalizing world are reproduced here.

This collection brings together leading specialists in the areas of European Union law which are now organized under the Area of Freedom, Security and Justice (AFSJ). The concept of the AFSJ was introduced into the EU Treaty framework by the Treaty of Amsterdam in 1997, and it incorporates migration law, family reunion law, asylum law, police cooperation, and cooperation in criminal law. Each of these areas of law is the subject of an in-depth examination in a separate chapter of this book.
The early years of the AFSJ, building upon a substantial body of law already in place under the Treaty of Maastricht and various intergovernmental arrangements, have witnessed a rapid expansion in legislative and executive activity in the field of European internal security. In migration law, family reunion law, asylum law, police co-operation, and co-operation in criminal law, the scale and intensity of action at the supranational level is already such as to overturn longstanding assumptions about the priority of national law in matters of migration control and criminal justice.

An introductory chapter examines the various policy strands covered by the AFSJ; investigates what, if anything, can be viewed as its distinctive legal underpinning; and discusses its possible future development in the light of current discussions over the adoption of a first documentary Constitution for the European Union. In addition to setting out the main contours of legal policy, each chapter examines the continuing tension between national sovereignty on the one hand and a growing commitment to collective, EU-wide action on the other. The volume also addresses the wider constitutional implications of a growing supranational capacity in questions of the priority of political values in the evolving EU; fundamental rights protection; the control of new forms of executive and administrative discretion; and the pressures of accommodating the ten new Enlargement states within the internal security field.

Constitutional discourse has perhaps never been more popular, nor more comprehensively challenged than it is today. The development of new constitutional settlements and languages at state and post-state level has to be balanced against the deepening of a formidable range of sceptical attitudes. These include the claim that constitutionalism remains too state-centered, overstates its capacity to shape political community, exhibits an inherent normative bias against social developments associated with the politics of difference, provides a language easily susceptible to ideological manipulation and, that, consequent upon these challenges, it increasingly represents a fractured and debased conceptual currency. A rehabilitated language of constitutionalism would meet these challenges through a version of constitutional pluralism. Constitutional pluralism recognises that in the post-Westphalian world there exists a range of different constitutional sites and processes configured in a heterarchical rather than a hierarchical pattern, and seeks to develop a number of empirical indices and normative criteria which allow us to understand this emerging configuration and assess the legitimacy of its development.

(Note: Italian version “Una costituzione con la “C” maiuscola o con la “c” minuscola?” published in (2005) 25 Quaderni costituzionali 881-884.)

This paper examines the long evolution of the EU’s unresolved constitution. Where the state is generally considered as a culturally prior, comprehensive, exclusive, monopolistic, singular, accomplished, determinate and settled political form and constitutional polity, the EU remains an accessory, partial, complementary, competitive, composite, incipient, indeterminate and disputed political form and constitutional polity. Over the last 15 years, as the relatively consensual law-centred focus of the EU’s early and ‘thin’ constitutional settlement has come under increasing strain, the unresolved nature of the EU constitution has become more palpable. In this regard, the failed Big ‘C’ constitutional project has to be seen as the symptom of a continuing problem rather than as some kind of 'closure' event. The challenge to EU constitutionalism today is to stand above the various and divisive polity visions with which it is often and self-defeatingly associated in the name of an expressive commitment to the very idea of a European common good notwithstanding these different polity visions.

The paper asserts the enduring significance of ‘sovereigntist’ thinking not just at the rhetorical surface of EU discourse, but as a deep organizing theme of its constitutional politics. It argues that the ‘sovereignty surplus’ of the EU — referring to the excess and overlapping quality of claims to sovereignty in the EU (i.e. that ultimate authority is claimed both for the supranational centre and for the member states) and to the competition over scarce legal, political and cultural capital that arise from the simultaneous pursuit of these claims — underscores the notorious ‘democratic deficit’ of the EU in three ways. The sovereignty surplus is, first of all, the deep cause of the democratic deficit, in that competition over sovereignty’s scarce symbolic and organizational capital frustrates the development of EU-wide democracy. Secondly, the very gravity and divisiveness of what is at stake for the various parties involved and for the positions implicated in the ‘sovereignty surplus’ renders the question of the proper diagnosis and treatment of the ensuing democratic deficit highly controversial and, indeed, sharply polarised. Thirdly and finally, and bringing us back to the recent controversy over the aborted EU Constitution, the sovereignty surplus also makes the question of praxis — of how to secure the very ground of initiative necessary to develop and act on a more inclusively resolved diagnosis and treatment of the democratic deficit — whatever that may be, difficult if not intractable. The paper concludes by arguing for the importance of keeping that last question on the legal and political agenda, even — indeed especially — in an age of constitutional fatigue.

This paper contends that the relationship between democracy and modern constitutionalism possesses an underappreciated complexity, which, unless addressed, prevents us from embracing the challenge to constitutionalism or the possibilities open to it in today’s globalising world. That complexity is revealed by treating democracy as an incomplete ideal, referring both to the empirical incompleteness of democracy as unable to supply its own terms of application - the internal dimension - and to the normative incompleteness of democracy as guide to good government - the external dimension. This double-edged incompleteness explains the contingent necessity of modern constitutionalism. Constitutionalism is a necessary response to democratic incompleteness - seeking both to realise democracy (the internal dimension) and to supplement and qualify democracy (the external dimension). Yet, if incomplete democracy requires the accompaniment of constitutionalism, such incompleteness also means that democratic considerations cannot specify definitively the content of constitutionalism. The content of constitutionalism as a means to completing democracy, therefore, remains contingent upon other normative and practical considerations. Democratic incompleteness thus remains both the justificatory foundation for contemporary constitutionalism and the main reason for its inherent fragility. The paper proceeds by examining the relationship between democracy and constitutionalism along various internal, external and mixed dimensions, observing that some of the ways in which constitutionalism treats democracy recur over time and circumstance. Yet how democratic incompleteness manifests itself, and how constitutionalism responds to incompleteness, also evolves and alters, revealing the relationship between constitutionalism and democracy as iterative. The paper then concentrates on the iteration emerging from the current globalising wave. The fact that states are no longer either the exclusive sites of democratic authority or the only constitutional entities and sources compounds democratic incompleteness and complicates how constitutionalism responds. Nevertheless, it is argued, the historical role of constitutionalism in political modernity as key to addressing the double incompleteness of democracy persists under globalisation, as does democracy’s inability to supply all vital terms of constitutionalism. This continuity reflects how the deep moral order of political modernity, in particular the emphasis on individualism, equality, collective agency and collective self-improvement, remains constant while its institutional architecture, including the forms of its commitment to democracy, evolves. Constitutionalism, itself both a basic orientation and a set of design principles for that architecture, remains a necessary support for and supplement to democracy. Yet postnational constitutionalism, even more than its state-centred predecessor, remains contingent upon non-democratic considerations, so reinforcing constitutionalism’s normative and sociological vulnerability. This conclusion challenges two dominant but opposing understandings of the postnational constitutionalism of the global age - both that which indicts global constitutionalism because of its weakened democratic credentials and that which assumes that these weakened democratic credentials pose no problem for postnational constitutionalism, which may instead thrive through a heightened emphasis on non-democratic values.

This paper examines the unresolved questions in Neil MacCormick's theory of post- sovereignty (in the context of the EU and more widely) in the light of his broader efforts to reconcile different strains in his intellectual and political world-view—universalism and particularism, cosmopolitanism and localism, internationalism and nationalism. It concludes that on that broader and deeper basis he might well have been drawn to a very thin form of universalism—namely a kind of inter-systemic framework of exchange involving mutually autonomous universalisation requirements.

This paper asks whether and how modern law may be understood as necessarily public in character. It begins by looking at the two main ways - doctrinal and disciplinary - in which law is understood as only selectively and contingently public. In both these cases law's public quality is counterposed to its private quality. However, publicness can also be conceived of as the juridical master category embracing the public and the private in the disciplinary and doctrinal senses. This conception of the necessary and irreducible publicness of law draws on the tradition of ius publicum, recently revived in the Anglophone world in the work of Martin Loughlin. That body of thought conceives of the state as a pre-positive and generically public jural foundation - a scheme of intelligibility for making sense of the positive law (constitution, statute law, common law) of the state. This is a plausible and powerful way of understanding the history of the modern state-based, sovereigntist legal constellation. However, it may be challenged both methodologically for elevating the state-based account to the status of the only plausible narrative, and substantively for its inability to capture the state-decentring aspects of contemporary globalization. A conception of pre-positive publicness no longer simply proposed as a dominant, value-neutral historical paradigm of explanation, but now underpinned by a normative commitment to democracy, is proposed as way of addressing both the methodological and the substantive limitations of the ius publicum account.

This paper considers whether, why and to what extent we should conceive of transnational regulation in constitutional terms. It distinguishes between two different candidates for transnational constitutional status. On the one hand, there are various actual or potential 'holistic' transnational constitutions, such as the EU and the WTO. These constitutional orders resembe that of the state to the extent that they involve the framing of a distinct 'body politic'. This 'body politic' may be thinner or thicker, depending on the number and richness of the framing layers involved (legal order, politico-institutional complex, popular self-authorization, distinct society or demos), but the idea of the constitution as a constituent dimension and expression of a broadly encompassing, internally coherent and externally bounded polity is present in all cases. On the other hand, there are also today various international societal actors and functional spheres (e.g internet regulation, sport regulation) that on one view possess their own 'societal constitutions'. Unlike holistic forms of regulation, however, these areas tend to combine very narrow forms of self-regulation with diverse forms of external regulation. The idea of a discrete framing is not present even in legal or institutional terms, still less in popular or social terms. Nevertheless, the paper argues, there may be good normative reasons for continuing to use the language and mindset of constitutionalism in these contexts.

Modern jurisprudence has been dominated by questions of authority and questions of meaning. The present paper addresses what it calls the third question of jurisprudence - namely the question of how law situates itself in space and time. This is a question to be addressed at various levels, the most important of which concerns the overall legitimacy of law as a normative enterprise which claims to come from somewhere and 'somewhen' and to be directed to somewhere and 'somewhen'. In the Westphalian tradition in which the dominant forms of law have been constitutional law and international law, this question of self-situation has tended to be answered either in highly universalistic terms (a law that transcended place and time) or in highly particularistic terms (a law that was peculiar to a particular place and perpetual in its ambition) . Both universalistic and particularistic narratives, despite their superficial contrast, emphasize the holistic and magisterial properties of law - as a form of authority that is both comprehensive and self-contained and sovereign within its situation. Today, with the fading of the Westphalian paradigm and the growth of myriad new forms of transnational law, various forms of new regulation - pluri-constitutive, interstitial, non-constitutive and global general law - lack the background co-ordinates either of universalism or of a comprehensive particularism and the associated systemic qualities of holism and magisterialism. What do these new forms of 'uncharted law' suggest more generally about the future of the legal form and of the ways in which law may legitimate itself?

The category of the denizen is becoming increasingly important in the identity politics of the EU. EU law and policy over a number of years has encouraged the development of a new hybrid status of the permanent resident who possesses many legal and social rights but lacks full political citizenship. Thinkers and politicians differ over the implications of this development, some seeing it as a temporary status on the way to full citizenship, others seeing it as a permanent sub-citizenship status, and others still seeing it as a way of moving beyond the citizenship/non-citizenship dichotomy in understanding the relationship between individuals and political communities. The paper explores this third alternative at some length, and concludes that the figure of the denizen may indeed be an appropriate archetype for imagining political community at the supranational level.