Examination of the state- centric dynamics of constitutions can only partially illuminate the multi- faceted characteristics of constitutional law. A statist focus often obscures both internal and external dimensions of constitutions themselves, and of the broader structures and patterns of governance that exist within and beyond nations. Either explicitly or implicitly, constitutions speak to the sub- as well as to the inter- and supra- national, and provide a lens through which obligations and pressures arising in each differing context might be refl ected. Constitutions are, as such, inherently multi- layered.

The focus of this chapter is not primarily on the forms taken by multilevel governance structures, 1 but rather on the accommodation and integration of multiple layers of government via national constitutions and the tensions to which multiple layers of constitutional authority give rise. The chapter takes as a point of departure the suggestion that though national constitutions can be accepted and interpreted as monolithic, or standalone, entities, understanding their place as a conduit between sub- national, national and international norms and institutions is vital to a full appreciation of their character and qualities. Constitutions are often explicitly contingent upon sub- national and international sources of authority, others may be centralized to the virtual exclusion of other sources of normative power. But – as Vandenbruwaene has observed – the place of national structures of government is, regardless, increasingly seen as but one source of normative authority among many of varying, potentially intersecting, geographical ranges:

The 21st century is marked by an increased recognition, both empirical and normative, of a complex world, which is simultaneously fragmented and interdependent. These co- existent trends, one of globalization and one of localization, yield a bifurcated pressure on the unitary nation- state: on the one hand, the circumspection of the relevant polity is subjected to change because of particular claims – the rise of regional authority based on identity politics springs to mind. On the other hand, the necessity of effective governance suffers from interdependencies and mobility, frequently exceeding national borders. 2

In the United Kingdom the diffusion of power away from Westminster and Whitehall – once seen as bywords for centralized national government – during the last fi fty years provides a case in point. Acceptance of the right of individual petition to the European Court of Human Rights in 1966 and accession to the European Community (as was) in 1973 combined to permit extra- jurisdictional institutions a signifi cant role in shaping domestically applicable norms and policy. The internal devolution of legislative powers to institutions in Northern Ireland, Scotland and Wales saw – from 1999 onwards – the wholesale geographical transfer of powers previously exercisable at Westminster to three sub- national legislatures (and executives). 3 The cumulative effect of these developments was a signifi cant reconfi guration of governmental power posing a series of challenges to the established unitary understanding of the UK constitution. 4 These decentralizing and internationalizing initiatives have seen the United Kingdom constitution take on ‘the appearance of a structure with multiple, but inter- connected and sometimes overlapping layers’. 5

For many jurisdictions, of course, a geographical distribution of powers (and the division of sovereignty between local and national- level units) is an inherent feature of constitutional government. Notwithstanding this, trends towards ‘sub- state nationalism’ 6 and a ‘new regionalism’ 7 have led to the establishment of governmental structures that have been pragmatically retrofi tted onto an established constitutional architecture or have otherwise prompted refi nement of accepted understandings of constitutional structures of national government. 8 Federal and non- federal solutions to the accommodation of sub- national government alike recognize intra- state diversity and the imperative of subsidiarity, but do so through either constitutionalized arrangements (e.g. Australia, Canada, Germany) or other sub- constitutional mechanisms of governmental decentralization (e.g. France, Spain, the United Kingdom). Both present alternative loci of power which might be seen to challenge – or at the very least prompt refi nement of – state- centric visions of constitutional authority. The jurisdictional integrity of the state and ability of the constitution to map allocation of governmental powers may also be challenged by developments on the international plane. As states have sought to operate collectively (e.g. via treaty- based organizations such as the Council of Europe, the African Union, the Association of Southeast Asian Nations) and to pool sovereignties in semi- autonomous supra- national legal structures (e.g. the European Union) the exercise of competences ‘above’ state- level institutions has become commonplace. Though the extent to which such upward dispersals of constitutional authority impact on domestic affairs may vary – both as a result of the substantive powers exercised beyond the state and the means by which such powers will be domestically effective or enforced – the transfer of powers away from the state may challenge jurisdictional autonomy, raise questions relating to resolving issues of contested competence and see the political and economic authority of state institutions apparently diminished. In this age of ‘post- sovereignty’ 9 or ‘constitutional pluralism,’ 10 statelevel institutions – the typical receptacles of supreme legal power – are but one component of an increasingly complex series of governance networks across which constitutional authority is dispersed (and contested). For national legal systems, often characteristically wedded to the idea of law’s emanation from a single authority or institution, the diffusion of authority towards supra- and sub- national loci of power may pose particular diffi – culties for the continuing integrity of the notional ‘sovereign’ and therefore for one of the defi ning characteristics of the national constitution.

1 On which see the chapters by Raffaele Bifulco, Jan Klabbers and Kaarlo Tuori in this
volume.
2 W. Vandenbruwaene , ‘ Multi- Level Governance through a Constitutional Prism ’ ( 2014 ) 21
Maastricht Journal of European and Comparative Law 229 , 230 .
3 The United Kingdom’s experience of devolution pre- dates the initiatives of the late twentieth
century. Between 1921 and 1972, devolved government had operated in Northern
Ireland as a result of the Government of Ireland Act 1920. Political confl ict in
Northern Ireland saw the reestablishment of direct rule in 1972, and the Parliament of
Northern Ireland was abolished by the Northern Ireland Constitution Act 1973. The late
1970s also saw failed efforts to establish devolved institutions in Scotland and Wales
(see V. Bogdanor , Devolution in the United Kingdom ( Oxford University Press , 2001 ) , esp.
chs. 3 and 6).
4 N. Walker, ‘Beyond the Unitary Conception of the United Kingdom Constitution?’ [2000]
PL 384.
5 N. Bamforth and P. Leyland , ‘ Public Law in a Multi- Layered Constitution ’, in N. Bamforth
and P. Leyland (eds.), Public Law in a Multi- Layered Constitution ( Hart Publishing ,
2003 ), 3 .
6 S. Tierney , ‘ Sub- State Nations and Strong States: The Accommodation Impasse? ’ in S.
Tierney (ed.), Nationalism and Globalisation ( Hart Publishing , 2015 ) .
7 M. Keating , The New Regionalism in Western Europe: Territorial Restructuring and
Political Change ( Edward Elgar , 1998 ) .
8 See e.g. R. Sch ü tze and S. Tierney , The United Kingdom and the Federal Idea ( Hart
Publishing , 2018 ) .
9 N. MacCormick , Questioning Sovereignty: Law, State and Nation in the European
Commonwealth ( Oxford University Press , 1999 ) , ch. 8.
10 See e.g.: N. Walker , ‘ The Idea of Constitutional Pluralism ’ ( 2002 ) 65 MLR 317 .