A. Introduction: Integration Through Law
1 ‘European integration’ can be defined as the process whereby European states have developed close forms of cooperation in economic, political, social, and legal domains. These forms of cooperation have gone beyond the looser relationships they typically develop through diplomatic action under international law, whether bilaterally or multilaterally. The process of integration has both social dimensions—as political actors turn their attentions and shift their loyalties toward a new focus—and political and legal aspects, with the creation of new institutional structures and frameworks for action. However, integration can be understood not only as a process, but also as a political objective. In Europe since the Second World War, it has been widely understood as an objective which produces also peace, prosperity, and stability.
2 Regional integration along similar lines has been embarked upon by states in a number of other continents such as Latin America, parts of Africa, and East Asia. However, examples such as the Common Market of the South (MERCOSUR) or the Association of Southeast Asian Nations (ASEAN) are by no means as developed as what is now known as the European Union (EU), which is the primary, but not sole, framework for European integration. The most salient dimensions of European integration EU-style include the single market (encompassing the free movement of goods, services, capital, and persons), the single currency (the euro), the Schengen zone, and other policy areas, such as the regulation of the environment and competition policy. European integration has also come to be associated with commitments to democracy, the rule of law, and fundamental rights, which are commonly recognized as the core features of the ‘liberal constitutional’ polity. The EU is the first geographically and geopolitically significant bloc of countries displaying a higher degree of heterogeneity in economic, political, and cultural terms to have taken the process of integration so far beyond the core economic functions of a common market with basic common institutions. Delivering on this wide prospectus has always been a substantial political and regulatory challenge.
3 European integration can be studied from a variety of disciplinary and interdisciplinary perspectives. Perspectives based in political science and international relations have been especially productive. A general introduction to European integration is often to be found on the curriculum for those studying many areas of social science, humanities, and contemporary history. However, one of the most important perspectives is that gained by focusing on the law of the EU. It is often said that the EU is a creature of law, established by treaties under international law and possessing autonomous institutions such as the European Commission, the European Parliament, and the Court of Justice of the European Union (CJEU). Indeed, it is certainly the legal characteristics of the EU which most clearly distinguish it from other endeavours to construct systems of regional economic integration based on treaties. Much of what the EU does is based on what is termed ‘supranational’ law, where it is the institutions themselves which are the primary law makers, making use of competences conferred upon them by the Member States. This is contrasted with the typical ‘intergovernmental’ mode that tends to dominate in other regional integration organizations. This requires the unanimous agreement of the states involved before any measures can be agreed. The EU, by contrast, operates in many areas of its competence by a qualified majority of its Member States, sitting in the Council of the EU. Furthermore, the Council is only one part of the EU’s legislature, along with its directly elected Parliament.
4 These points make clear that there are many similarities between how the EU operates and how states operate. Following Max Weber, it is often said that modern states have three distinct elements: a territory, a government, and a people. The EU has a territory, comprised of the 27 Member States (as of 1 February 2020); a government, made up of its institutional structures, which operate the competences and legal frameworks under which the EU operates; and a people, in the sense of the citizens of the EU, who are the nationals of the Member States. However, this description fails to capture the key differences between states and the EU as a legal and political organization. The EU is a legally constituted framework within which the Member States have ‘pooled’ or shared their sovereignty, and in that limited sense the EU itself has sovereign powers, but only within the scope of the competences established by the treaties and the powers of the institutions to interpret and apply those competences. Notably, the CJEU has asserted since the earliest days that, although what were then the ‘European Communities’ were based on international treaties, these treaties have operated as the Communities’ ‘constitutional charter’, which have ensured that the Communities were based on the rule of law. The CJEU comes back to these points in those judgments in which it revisits and, where necessary, updates the basic operating system of the EU. The recent Wightman case offers a good example, and the following quotation highlights how the ideas have been threaded through successive constitutional cases:
5 In Wightman, the CJEU was considering whether the United Kingdom (UK)—which had notified its intention to leave the EU making use of the procedure laid down in Article 50 of the Treaty on European Union (TEU)—could revoke that notification. This was a novel situation, and in its response to the questions asked by the Scottish Court of Session, the CJEU reinforced the voluntary nature of participation in the EU. Voluntary participation also implies the voluntary nature of departure, so the UK could not be forced to leave if it changed its mind. This highlights how the EU is a creature of states, and not a state itself. It is often called a polity ‘beyond the state’, to highlight that the vocabulary of ‘stateness’ offers only limited insights into what the EU’s purposes are and how it operates.
6 In order to gain a better understanding of how ideas about European integration underpin EU law and how law affects integration, three questions will be explored in more depth in the three following sections.
B. The Evolution of European Integration
7 The idea of a unified Europe is by no means new. The model of a Europe brought together not by military conquest, but in common pursuit of higher goals of peace, prosperity, and stability has attracted the attention of thinkers since the Middle Ages. After a nationalist resurgence became one of the contributing factors for the First World War, the inter-war years saw renewed discussion of the ideal of European integration as a better way forward for Europe than destructive interstate rivalry. However, the only initiative at the governmental level put forward to promote European integration in the interwar years was a plan developed by the French Foreign Minister to promote an economic union in Europe (Briand Plan). This proposal never gained much traction, not least because of the effects of the Great Depression after 1929. However, it sowed the seeds of some of the ideas that eventually emerged from the wreckage of Europe after the Second World War as concrete plans for European integration.
8 Momentum towards European integration could be seen already during that war, articulated by resistance figures such as Altiero Spinelli, who later re-emerged as a champion of European federalism in the European parliament in the late 1970s and 1980s. The development of federal institutions, including a written constitution, a judicial system, and a common army were some of the ideas put before a conference of resistance representatives in Geneva in 1944. After the war, however, it was in fact the established pre-war politicians who returned to power as the new democracies in western Europe emerged, rather than the more radical figures who had featured in the various resistance movements. It was therefore unsurprising that a sense of gradualism dominated subsequent moves towards integration, involving the establishment of the precursors to today’s European Union: the 1952 European Coal and Steel Community (ECSC), the 1958 European Economic Community (EEC), and European Atomic Energy Community (Euratom). By that stage, however, there was already a dense network of forums for international cooperation in Europe, including the Council of Europe and the European Convention on Human Rights and Fundamental Freedoms (ECHR), established in 1949, the United Nations Economic Commission for Europe (UNECE), and what subsequently became the Organisation for Economic Cooperation and Development (OECD). After 1945, Europe was a laboratory involving several different experiments with European integration, not all of which were confined to the western part of the continent. However, amongst the foremost driving forces for integration was the anti-communist logic of the United States (US) Truman Doctrine, a pledge of support for ‘free peoples who are resisting subjugation by armed minorities or by outside pressures’. The prevention of a destabilizing power vacuum in Europe led to the adoption of the Marshall Plan as the framework for the US to provide economic aid from 1947 onwards. This contributed substantially to the concretization of the east/west divide and the opening salvos of what became known as the Cold War.
9 An important new chapter in the evolution of European integration opened with the publication in May 1950 of the Schuman Plan, drawn up, on behalf of the French Foreign Minister Robert Schuman, by Jean Monnet. Monnet had been heavily involved both during and after the war in a number of initiatives to foster cross-national cooperation, most dramatically the offer which Winston Churchill made in 1940 that France and the UK should create a federal Franco-British Union. After the war, Monnet was employed in the French civil service and was heavily involved in national economic planning. This is strongly reflected in the drafting of the Schuman Plan, which focused on the proposal to place French and German coal and steel production under a common authority (a ‘High Authority’) outside national control and open to the participation of other European countries. The simple idea was that coal and steel production lay at the heart of the war preparations, and that—if placed beyond national control—this would render war between the participating countries inconceivable. A wider agenda was also evident in the Schuman Plan, including references to a federal future for Europe, but the overall vision is seen most clearly in the following well-known statement: ‘Europe will not be made all at once or according to a single plan. It must be built through concrete achievements which first create a de facto solidarity’.
10 The Schuman Plan led to the ECSC based on a Treaty concluded in Paris in April 1951 and involving six countries: France, Germany, the Benelux (Belgium, Netherlands, and Luxembourg), and Italy. The Treaty, which came into force in January 1952, established a High Authority as an independent actor, which was charged with the principal decision-making power, as well as a Common Assembly, a Council of Ministers, and a Court of Justice. Some aspects of the framework were strongly supranational, as decisions could be taken and then implemented by the High Authority without requiring a consensus of the Member States. Much of this four-pronged institutional framework was adopted for the later Treaties of Rome of 1957 which inaugurated the other two Communities, namely the EEC, which gradually came to dominate the domain of European integration, and Euratom. Under the EEC Treaty, what is now called the European Commission (no longer the High Authority) was still independent of the Member States, once appointed. It had executive power as well as the power to initiate legislation, but decision-making power had shifted to what was then the Council of Ministers. That is to say, it now lay with the representatives of the Member States. At least initially, the Council of Ministers was to decide on legislation unanimously, giving each country a veto. As with the ECSC, the Assembly had only a consultative role in relation to legislation under the original EEC Treaty.
11 However, there was no smooth pathway from the ECSC to the EEC, for between the two Communities came another failed initiative to build a further distinctive element of the patchwork of European cooperation institutions: a European Defence Community and a draft statute for a European Political Community. This initiative was successfully negotiated amongst the governments of the same six Member States but failed to pass the ratification hurdle before the French Parliament in 1954. This initiative was designed to apply the methods of the ECSC in the field of defence in order to allow for German rearmament, at that time being strongly urged by the US, under the umbrella of a common European army. In the end, alternative routes were found to incorporate Germany within Western European and North Atlantic security cooperation which did not involve anything as dramatic as a common European army. These routes involved other European actors beyond the original six Member States, notably the UK, which had excluded itself at an early stage from the various sets of negotiations on economic integration, and states such as Norway, as well as the US and Canada, which were all founding members of the North Atlantic Treaty Organization (NATO). It took a further relaunch of economic integration through the initiative of the smaller Member States for the contracting parties eventually to agree on the EEC Treaty in 1957 (at the Messina Conference in 1955).
12 Like so many of the founding documents of the European integration process, the EEC Treaty contained paradoxical elements. It began with the grand ideal that the contracting parties were ‘determined to create an ever closer union amongst the peoples of Europe’. Yet, although the generic term ‘economic’ was used in the title of the Treaty, in reality its ambitions were more limited and focused particularly on the creation of a common market for goods, services, persons, and capital, the establishment of a customs union and common external tariff, the adoption of common policies in areas of competition and state aid to buttress the common market, and a common agricultural policy.
13 The vision set out by the EEC Treaty was one of gradualism and incrementalism, in which the various policies articulated compromises between the diverse and often conflicting interests of the Member States. For example, the inclusion of agricultural policy—when common policies in many other areas were not proposed—was widely regarded as a trade-off favouring France, against the inclusion of the free movement of people within the common market programme, as requested by Italy.
14 Soon after the entry into force of the EEC Treaty, some of the non-participants in ‘supranational Europe’, notably the UK, concluded a treaty establishing the European Free Trade Area (EFTA). This was a more limited form of economic cooperation, involving the removal of internal barriers to trade such as tariffs, but not the creation of a common external tariff. It did not have autonomous supranational institutions. Furthermore, a free-trade arrangement bridging between EFTA and the EEC proved impossible to achieve, notably because of the hostility of the French President de Gaulle, who also vetoed the UK’s early attempts to join the EEC.
15 It was helpful for the nascent EEC that the years of the late 1950s and the early 1960s were ones of rapid economic growth. This created a certain momentum. During most of the transitional period up to 1970, the EEC was to operate, by design, through consensus of its Member States. But the early 1960s also saw the new Court of Justice busy building the foundations of a supranational legal order, based on a transfer of sovereign powers by the Member States to the Community. The Court started developing the concepts that underpin the relationship between the law of the European Communities and national law (supremacy, direct effect, direct applicability), making it clear that within the sphere of its competences European Community (EC) law took precedence, even over national constitutions. The Court also placed the individual at the heart of the Community legal order and envisaged a role for national courts in enforcing the provisions of EC law.
16 The first political difficulties were encountered towards the end of the transitional period, when voting in some areas—for example, on agricultural policy—was supposed to move to qualified majority voting (‘QMV’), thus eliminating a national veto. De Gaulle famously pulled French officials and ministers out of meetings with the other Member States in 1965 (Empty Chair crisis) and did not return until the other Member States had accepted the continuation of the national veto in areas where key national interests could be asserted (the Luxembourg Compromise). As a result, from the mid-1960s until the mid-1980s there was a period of what is generally termed ‘eurosclerosis’, when progress towards the goals of the treaties seemed to have stalled. This was compounded by successive economic downturns from the early 1970s onwards.
17 The major breakthrough, from an institutional perspective, came with the Single European Act, which came into force in 1986, installing the 1992 Single Market goal and opening the door to more (and genuine) QMV and an enhanced role for the (now directly elected) European Parliament in the legislative process. It also tentatively set what had come to be known as the ‘European Communities’ on a pathway away from an exclusive focus on economic and trade matters towards other areas which had traditionally been seen as matters of national sovereignty such as social policy, justice and home affairs, internal security policy, and foreign policy.
18 The period between 1958 to 1986 represented a substantial time gap during which there were no changes to the founding treaties. From 1986 until 2009, there was regular treaty change, with new bargains reached (sometimes painfully) between the Member States in intergovernmental conferences as follows: Treaty of Maastricht, 1993; Treaty of Amsterdam, 1999; Treaty of Nice, 2003; Treaty of Lisbon, 2009. Each of these treaties has been ratified at the national level (again, sometimes after certain difficulties were encountered) and entered into force.
19 This succession of new treaties—along with an accelerated and more effective legislative and implementation process within the institutions—signalled a stronger political will to reap the economic benefits of the integration process, as well as to explore what might lie beyond its current limits. The best example to illustrate this point stems from the political drive to achieve monetary union and to introduce a single currency from 2002 onwards, contained in the Treaty of Maastricht. This process moved forward successfully, even though the institutional architecture established for monetary union has been found somewhat inadequate over the decades, especially in the aftermath of the financial crisis from 2008 onwards. That crisis subsequently became a sovereign debt crisis for several Member States, requiring special and difficult measures to be taken, in particular for and by Greece. The architecture of monetary union, lacking the instruments of economic policy necessary for such crises, has had to be supplemented by a number of changes which fall short of formal amendments to the EU treaties as a whole.
20 In recent years, the classic intergovernmental bargaining process for treaty change set out in the original treaties has been backed up with a broader ‘Convention’ process for developing proposed changes to the treaties, involving a wider range of stakeholders (eg from national parliaments and the European Parliament). This was used once at the end of the 1990s for the formulation of the EU’s Charter of Rights and then later at the beginning of the 2000s for the negotiation of what was known as the Constitutional Treaty. At the end of 2019, a new initiative was launched to create a Conference on the Future of Europe to look at future policies and institutional arrangements, directly involving citizens themselves in shaping the future EU. Progress on this initiative was delayed until 2021 by the COVID-19 pandemic and given the green light by what is now the Council of the EU in March 2021.
21 The story of the Constitutional Treaty is instructive, in so far as it highlights that although treaty change has been relatively frequent since the 1980s, it has faced important hurdles. This proposed treaty was eventually abandoned because it was rejected in referendums held in France and the Netherlands (spring 2005). Much of the text of the Constitutional Treaty, shorn of its ‘constitutional’ symbolism, was subsequently resuscitated in the Treaty of Lisbon, which instituted the current architecture of what we now know as the European Union. The EU is now based on two key treaties: the TEU, which contains most of the classically ‘constitutional’ provisions underpinning the basic set up of the EU as well as some policy-related provisions in the sovereignty-sensitive intergovernmental fields of external action and common foreign and security policy, and the Treaty on the Functioning of the European Union (TFEU), which contains the provisions governing most policy domains, both those which are little changed since the original Treaty of Rome (eg in the area of the single market) and those which were introduced during successive treaty amendments (eg citizenship of the Union, Economic and Monetary Union, or justice and home affairs). The TFEU also contains detailed institutional provisions, which make it clear, for example, that a legislative process in which the Council of the EU and the European Parliament are co-equal legislators, and which requires QMV amongst the Member States is the ‘ordinary’ default legislative procedure. Only in exceptional cases is unanimity still used. This constitutional architecture promises to be somewhat more durable than the problematic ‘pillar structure’ introduced by the Treaty of Maastricht, which tried to separate the supranational elements of integration (the first pillar) from the intergovernmental elements (second pillar: common foreign and security policy; third pillar: justice and home affairs).
22 The Treaty of Lisbon was initially rejected in a referendum—this time in Ireland (June 2008). However, after a period of reflection and reassurance aimed at Irish voters, combined with certain guarantees that were subsequently legally enshrined, it was put before them again in a second referendum (October 2009). Second time around, the Treaty was accepted by a considerable majority and so could enter into force (1 December 2009). Other treaties have also faced ratification referendum hurdles such as the Treaty of Maastricht (Denmark 1992) and the Treaty of Nice (Ireland 2001), but each time these failed referendums have been overcome with second referendums. What these challenges have signalled, however, is that it should not be taken for granted that national electorates will simply accept whatever is placed in front of them by national leaders. Moreover, sometimes national parliaments have also been reluctant to approve ratification measures put before them by the executive responsible for negotiating and signing treaties. For example, parliamentary debates were particularly acute in the UK in the case of the Treaty of Maastricht. Furthermore, it is clear, as in Ireland with the Treaty of Lisbon, that the electorate may need additional assurance about the protection of nationally sensitive issues such as neutrality before providing the seal of approval in a referendum. Away from Ireland, these difficulties, as well as the results in the five yearly European Parliament elections, have signalled the rise of various forms of Euroscepticism and anti-EU sentiment amongst the electorates of many of the Member States.
23 From the 1970s onwards, the process of European integration through the Treaties of Rome and Paris proved attractive for other European states, with enlargements in 1973 (Denmark, Ireland, UK), 1980 (Greece), and 1986 (Portugal and Spain). After the end of the Cold War, came Austria, Finland, and Sweden (1995), moving many of the key participants in EFTA into the EU. From 1994, participants in EFTA were linked to the EU through a wider economic framework: the European Economic Area (EEA). More significantly, the comprehensive political and geopolitical changes after 1989 opened the door towards a major enlargement in 2004, involving eight post-communist countries of central and eastern Europe (Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, Slovenia) and two southern European microstates (Cyprus and Malta). Enlargement towards that region continued with Bulgaria and Romania (2007) and Croatia (2013). Enlargement further into southeastern Europe has, however, stalled, leaving candidate countries such as Montenegro and the Republic of Northern Macedonia frustrated. The year 2020 saw a dramatic and unprecedented shift in the shape of the EU. While a number of territories had left the EU whilst remaining component parts of Member States (notably Greenland which left the EU in 1985 but remains an autonomous territory of the Kingdom of Denmark), until the UK left the EU on 31 January 2020 after a referendum in June 2016, withdrawal of a Member State from the EU had never happened. While the EU continues to face many crises, however, there is little evidence that the UK’s departure (‘Brexit’) will generate a domino effect amongst other Member States.
24 Some aspects of deepening have already been mentioned, particularly in the incremental enhancement of basic building blocks such as the single market but also in innovations such as monetary union. The EU has also developed important policies in the external sphere, including not only matters of trade but also political and security cooperation, and some cooperation in the sphere of defence. The Treaty of Lisbon introduced many important supranational innovations in this field, whilst retaining scope for elements of Member State control.
25 The Treaty of Amsterdam inaugurated the idea of the EU as an area of freedom, security, and justice. This offers a useful framework to highlight how the EU now intrudes into many areas which are seen historically as sensitive matters of national sovereignty, such as immigration, criminal law, and aspects of internal security. The logic of the free movement of persons not only generated important possibilities for EU citizens (and their families) to live, work, study, and retire in and to other Member States, and to enjoy the right to non-discrimination on grounds of nationality, but it also raised the question of why internal borders should continue to exist between the Member States. Within the so-called Schengen Area, which encompasses 22 Member States plus four other European states, restrictions on mobility have been substantially removed, based on the creation of common external frontier standards, a single (Schengen) visa, and the establishment of a number of databases which permit the sharing of information about individual and collective security threats. Of course, that edifice can crumble in the face of shocks, none of which have been greater than the COVID-19 crisis of 2020–2021 which saw the closing of internal and external borders across much of Europe for many months. Furthermore, this area of EU integration has been strongly marked by differentiation and varied speeds of integration, with notable absentees from the Schengen Area being the UK (before and after Brexit) and Ireland (because of its geographical co-location with the UK and the so-called Common Travel Area), as well as the newer Member States of Bulgaria, Croatia, and Romania, which have not yet put the necessary infrastructure relating to external borders in place. Another component of the area of freedom, security, and justice has involved the emergence of a body of EU immigration law and EU criminal law, again with marked differentiation for some Member States. Levels of differentiation to cater for specific Member States have decreased since the departure of the UK, but it continues for Ireland and (in some areas) Denmark. One dramatic innovation in the sphere of criminal justice and internal security has been the European Arrest Warrant, which has superseded the traditional extradition process for surrendering suspects between independent sovereign states.
26 In sum, the character of the EU in the 2020s is profoundly changed from that of the original Communities in the 1950s. This is not simply due to the passage of time, and changed geopolitical and economic conditions, but is also a function of processes of widening and deepening and the successive crises that it has faced from the oil crises of the 1970s to the multiple crises of the 2010s and 2020s, including the COVID-19 pandemic and the erosion of the rule of law and liberal democracy in several EU Member States. Even so, there are strong continuities between the institutions and policies devised in the 1950s and the position of the EU of the 2020s. It is therefore too early to tell whether the momentum that has been drained from the so-called integration process will be recovered as the world recovers from the impact of the pandemic and as policies to combat the degradation of democracy and the rule of law are gradually solidified within the EU, or whether the European continent will move decisively into a period of disintegration.
C. Explaining European Integration
27 Along with describing and analysing processes of European integration, scholars in this field have also looked for ways to explain these processes and to situate them within their broader political context. That is, they look for theories that help to explain why and how particular changes or events have happened. These theories not only explain but may also predict and problematize the process of European integration. They are important for understanding both the context and content of EU law.
28 Many dimensions of the EU and EU law remain contested, in political terms between different countries or political parties and groups, nationally and at the European level, as well as within public opinion at the domestic level. There has, for example, been a substantial rise of Euroscepticism in recent years in many Member States. Yet at the same time, there is also evidence of pro-EU activism, partly in response to the challenges posed by Brexit. Understanding the different theories about European integration can foster a critical and questioning approach to how the EU has developed and how it may change in the future, and about how processes of integration, differentiation and disintegration all relate to each other.
29 In addition, explanations of EU integration intersect with the various political movements which cluster around the EU as a political project. To give just one example: there is a distinct political movement which has pushed for the EU to move towards something more like a federal state (a sort of United States of Europe), going beyond the current hard-to-classify mixed intergovernmental/supranational polity which is how it currently presents. From time to time, political leaders have mooted federalist solutions to the problem of Europe’s ‘endgame’: that is, how to identify a stable and effective polity for the long term in the European political space. At the same time, there is a theory of European integration which argues that the EU, both presently and historically, is best understood using ideas about federalism. Federalism in that sense articulates ideas derived from how federal states actually function, as divided power systems. It does not necessarily focus on the political aim of promoting a European federal union or federation.
30 From the outset, there were two dominant academic approaches to understanding and explaining the European integration process, both of which originated in the study of international relations: neo-functionalism and intergovernmentalism. Neo-functionalism was probably the dominant account of early integration processes, at least up to the mid-1960s, when the European Communities encountered significant opposition to the deepening of integration. In the sphere of politics, it also underlaid the decision of the ‘founding fathers’ such as Jean Monnet and Robert Schuman to abandon grand federalist projects and to promote instead the adoption of the limited ECSC Treaty, which concentrated simply on putting two strategically important commodities into the hands of a central authority. One of the most significant elements of the gradualism identified by those who have used neo-functionalism to explain European integration is the concept of spillover: the initial first steps, for example to create a common market, created demand for further measures such as a monetary union. The free movement of persons gave an impetus to both the removal of internal borders and enhanced regulation, at the EU level, of immigration from third countries. The neo-functionalist scholars stressed the impact of interest associations and firms shifting their focus to the European level and exerting pressure for greater integration (including using litigation in national courts as a tool), as well as the effects of the socialisation of governmental elites involved in the bargaining processes at the European level. The essence of neo-functionalism, in sum, was that it offered an explanation for the integration process and its outcomes which went beyond states’ interests as the sole driving factor.
31 However, neo-functionalism as a theory of integration struggled to account for the prolonged period of stasis in European integration from the end of the 1960s until the mid-1980s, with its proponents arguably underestimating the power of national interests. Although it was subsequently revised, after the single market project in the 1980s and 1990s showed the renewed power of supranational institutions such as the European Commission and the CJEU in fostering further integration, neo-functionalism has struggled to achieve as much support from theorists as its main competitor theory of intergovernmentalism.
32 Proponents of intergovernmentalism explained European integration in terms of bargains struck between sovereign states, which saw that their geopolitical interests coalesced around a certain pooling of sovereignty in specific historic circumstances. This approach to understanding integration does not deny the existence of supranational institutions but argues for them to be seen essentially as the agents of states and governmental institutions at the national level. In terms of policies, this might be thought to work well as an explanation of much of what the EU has done. In terms of institutions, it struggles to account for the specific role of the CJEU in building an autonomous ‘new legal order’ of international law.
33 Over the years, the types of questions asked by those seeking to explain and systematize integration processes have evolved quite significantly. Since the 1980s a much greater emphasis has been placed not on seeing the EU solely as an unusual creature of international relations, but rather as an emergent polity in its own right, which faces the same sorts of governance challenges as any other type of polity. As the EU itself has matured as a polity, much of the focus of work shifted to better understanding the institutions, the ways in which they changed and the new networks within which domestic and supranational institutions found themselves as the scope of EU policies gradually widened. Many of the tools of the study of politics in a domestic context could therefore be brought to the fore, such as the comparative approach, which better explains how the EU works as a polity. In particular, the concept of Europeanization has emerged as a key vector for understanding not only how Member States ‘upload’ their own preferences to the EU level in order to shape policies according to their interests, but also—crucially—to provide tools to understand how domestic institutions and policies have been reshaped as a result of the treaty obligations that Member States have voluntarily taken on. Alongside approaches which drew upon the ideas of political science, more scope emerged for understanding the EU, its institutions, and its policies as societal phenomena, for which the tools of the discipline of sociology would also be useful. Above all, what is often termed the governance approach to understanding the EU leaves plenty of scope for theoretically informed enquiry into the legal dimensions of the EU’s polity, and in particular the question of whether the EU can be described as having some type of constitution, based on its treaties, other primary legal sources, and the interpretative case law of the CJEU.
34 It is clear that explanations for the integration process have needed to respond to changed circumstances over time. In particular, as the EU and its predecessors have confronted successive crises during its period of operation, so integration theory has been called upon to provide insights not only into cases where it is easy to see examples of deepening and widening, but also into cases of differentiation and even disintegration. The EU is a complex and ever-changing polity, which is both a creature of international relations between states, and somehow embedded within those states that voluntarily participate in this enterprise. Furthermore, the EU operates within a radically changed institutional and normative landscape across the world. The process of regional integration in Europe may be relatively far advanced, but it is not unique in the world, and comparisons with other continents provide important food for thought. The search for integration theories continues, but there have never been, and likely never will be, simple answers which explain everything about the paradoxical successes and failures of the EU since the inception of its predecessors in the 1950s.
D. How Does the EU Legal Order Structure and Facilitate ‘Integration’?
35 There are a variety of different ways to present the EU’s current legal order and to articulate how it relates to ideas of integration (and indeed differentiation and disintegration). There is, for example, an evolutionary and historical approach, which assesses the building blocks of the founding treaties and the case law of what is now called the CJEU from the 1950s onwards, showing, stone-by-stone as it were, how these have structured the integration/differentiation/disintegration/re-integration processes through successive interpretations of the changing treaties. A second approach works outwards from the treaties which are currently in force and explores—in the light of historical context—what type of legal framework for integration (and differentiation, such as opt outs) these now provide. Both approaches are capable of giving useful insights into core dimensions of the EU legal order, especially if they are paired with an awareness that both the law itself and the work of the judiciary need to be understood in the light of a wider political context in which integration processes are hardly uncontested by the relevant actors.
36 Whatever approach is applied, the central role of the CJEU becomes apparent. It has contributed to the evolution of European integration as a process by putting flesh onto the bares bones offered by the treaty structures as well as by providing some insights into one of the most important questions which faces the EU as a polity in the twenty-first century: to what extent should the language of constitutions and constitutionalism be used in order to evaluate the EU? That is to say, to what extent can it be argued that membership of the EU and involvement by states with EU law involves commitments to the typical characteristics of constitutions and constitutionalism, including adherence to the rule of law, the operation of a system of separation of powers, and evidence of some notion of a constituent power and a principle of democracy underpinning the legitimate exercise of powers? Of course, it might seem odd to suggest that a polity which is not a state and which has been set up as a matter of international law (treaties between states) should be evaluated against these types of standards, especially when we remember the story of the Constitutional Treaty in the 2000s. However, this type of argument has remained an important component of public discourse in and around the EU in recent decades. It has become increasingly widely recognized that the ideas of constitutional law and constitutionalism should no longer be confined simply to the domain of the state but provide useful benchmarks against which to assess the laws and practices of all manner of supranational and international entities, from the EU via the World Trade Organization (WTO), to the United Nations (UN) itself.
37 The case law of the CJEU on matters fundamental to the structure of the EU has remained quite steady over decades. Building on paragraph 44 of the judgment quoted above and drawing on judgments dating back to the 1960s, in Wightman, the Court enumerated the main constitutional pillars governing the relationship between EU law and national law in the following terms:
38 In facing a sensitive issue involving a Member State planning withdrawal from the Union, the CJEU found a way to reinforce what it regards as the voluntaristic nature of the EU as a compact of states. This is fundamental to its continued existence in legal as well as political terms. Wightman is one the very few examples of the CJEU explicitly invoking the terminology of ‘ever closer union’ in its case law. Thus, the CJEU argued that:
39 The reasoning and outcome in the Wightman case offers an important illustration of how EU law has evolved through judicial interpretation. Here was an instance of the CJEU filling out what might be regarded as a faulty or inadequate treaty provision (Art. 50 TEU), with an interpretation which drew inspiration from its own previous statements about the nature of the EU legal order. There is a circularity to this process, which allows the CJEU to accommodate the possibility of disintegration (ie withdrawal of a state from the Union) as a component of ‘ever closer Union’. Moreover, the CJEU provides this interpretation acting in partnership with a national court which, notwithstanding the hostility of the UK Government to an intervention by the CJEU on this aspect of Article 50, asked for this interpretation so it could decide a case that had come before it regarding the potential control of the executive by the legislature in the light of the provisions of EU law. That type of partnership has been a remarkable success story for the CJEU, in terms of it harnessing the enforcement and implementation structures of national judicial procedures in the service of the enforcement of the obligations under EU law and thus the authority of EU law. This has been buttressed in the many cases that have come before the CJEU regarding the independence of the judiciary in Poland such as Commission v Republic of Poland. Here, the CJEU concluded that the principle of effective judicial protection, enshrined in the second sub paragraph of Article 19(1) TEU, is sufficient to give the CJEU the competence to review various steps taken in Poland to eviscerate the independence of the judiciary. In such cases, the partnership between the national judges and the CJEU has often worked productively, but legal remedies at the supranational level can only go so far if the political will has evaporated both at the national and the supranational levels to protect the rule of law in a meaningful way in the EU. Ultimately, the rule of law cannot be effectively defended in a court of law.
40 Moreover, there have been plenty of examples of the defiance of national courts faced with the putative authority of EU law. For example, the German Federal Constitutional Court has followed up its circumspect case law on the protection of fundamental rights in the EU dating back forty years by categorically rejecting in 2020 the CJEU’s interpretation of some of the most ‘political’ parts of the edifice of legal provisions related to economic and monetary union. These measures had been put in place to secure the viability of the eurozone in the face of the sovereign debt crisis that came after the 2008 financial crisis, and upheld by the CJEU, but the German Court has warned that the German authorities should not remain signed up to them, for fear of breaching the German constitution. Keeping in place a multi-level constitutional framework for the EU through competing legal interpretations remains, therefore, an incomplete challenge, raising both legal and theoretical implications about plural sources of legal authority within a complex multi-level governance regime.
