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The European UnionHow does it work?

The European Union: How does it work? (6th edn)

Daniel Kenealy, Amelia Hadfield, Richard Corbett, and John Peterson
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9. Enlargement and Wider Europelocked

9. Enlargement and Wider Europelocked

  • Ulrich Sedelmeier
  •  and Graham Avery


The EU has expanded many times and many countries still aspire to join. Enlargement illustrates the success of the European model of integration. It has also provided the EU with a powerful tool to influence domestic politics in would-be members. But enlargement also poses fundamental challenges. It has implications both for how the EU works (its structure and institutions) and for what it does (its policies). The chapter first compares ‘widening’ and ‘deepening’ before discussing enlargement as a form of soft power. It then explains how the EU has expanded and why countries want to join. It also looks at wider Europe and the EU’s relationship with Norway, Switzerland, and Iceland, as well as prospective members in the Balkan countries. The chapter goes on to consider the EU’s relationship with Turkey and the European Neighbourhood Policy. The chapter concludes with a discussion of the potential limits of EU expansion and an evaluation of the enlargement process.


The EU has accepted new members many times, and many countries still aspire to join. The EU has extended the prospect of membership to countries in the Balkans as well as to Turkey, and has developed a wider ‘neighbourhood’ policy towards other countries, some of which may want to join in future. Enlargement illustrates the success of the European model of integration. It has also provided the EU with a powerful tool to influence the domestic and foreign policies of potential members. But enlargement also poses fundamental challenges. It has implications both for how the EU works (its structure and institutions) and for what it does (its policies). The EU has become increasingly cautious about further enlargement, which raises questions about its continued ability to use membership conditionality to bring about domestic changes that promote stability, prosperity, and good governance in would-be member states.

9.1p. 212 Introduction

The EU’s process of expansion goes to the heart of important questions about the nature and functioning of the Union. Why do countries wish to join it? How does the EU decide whether to admit a new member? How should the EU interact with its neighbours? How committed is the EU to further expansion?

It is often said that enlargement is the EU’s most successful foreign policy tool (e.g. Moravcsik 2017). The EU has indeed used the process of enlargement to promote prosperity, stability, and good governance reforms in neighbouring countries that want to join the EU. It has done so by setting demanding conditions for membership: would-be members have to carry out far-reaching reforms before they are allowed to join. The success of ‘accession conditionality’ (Box 9.1) gives enlargement a special place among the EU’s external policies.

However, enlargement is much more than foreign policy: it is the process whereby outsiders become insiders, and shape the development of the EU itself. In accepting new members, and formulating the conditions under which they join, existing members do not only make decisions on the EU’s future composition. They also enact, and refine, the EU’s collective identity (Sedelmeier 2005). In that sense, enlargement could be described as a constitutive policy (Sedelmeier 2020): in that when the EU makes choices about new members, it determines its own future.

9.1.1 Widening vs. deepening

The prospect of enlargement poses basic questions both for applicant countries and existing members. Before applying, countries need to analyse how membership will affect them. What will accession (Box 9.1) mean in political and economic terms? What will be the costs and benefits for an acceding country? How does the accession of a country affect the benefits of membership for an existing member? Is the acceding country’s political culture in line with the goals of European integration and the EU’s shared values? This kind of reflection raises questions of domestic interests and identity (Schimmelfennig and Sedelmeier 2002).

Box 9.1 Key concepts and terms

Absorption capacity refers to the EU’s ability to integrate new members into its system.

Accession is the process whereby a country joins the EU and becomes a member state.

Benchmarks in accession negotiations are conditions for opening and closing ‘chapters’ related to specific EU policies.

Candidate refers to a country whose application for membership the EU has confirmed, but which is not yet a member.

Conditionality refers to the fact that the EU makes the accession of a country dependent on its compliance with certain requirements for membership.

European Economic Area (EEA) is an arrangement that extends the EU’s single market to Norway, Iceland, and Liechtenstein.

Screening occurs at the start of negotiations when the applicant and the Commission examine the acquis to see if there are particular problems to be resolved.

Variable geometry, also known as multi-speed Europe or differentiated integration, is the idea that not all EU member states should take part in creating common rules in some policy areas (see section 4.2.3).

For the EU collectively, a recurrent theme in its development has been the tension between the ‘widening’ of its membership and the ‘deepening’ of integration between its members (Wallace 1989; Kelemen et al. 2014). Each time the EU contemplates a further expansion, its members are compelled to address fundamental questions about the purpose and the future of European integration.

p. 213When considering which states should be new members, the EU has to reflect on how the membership of this prospective member will affect its set of common policies and the functioning of its institutional set-up, as well as the prospects for changing or agreeing new, common policies and institutions in the future. Debates on the future of European integration regularly accompany enlargement. The ‘widening vs. deepening’ debate can seem to reflect competing interests between prospective members and current ones, but it is in their common interest to ensure that after enlargement the Union still has the capacity to take decisions effectively. Enlargement policy is thus linked with wider debates on, and has been a trigger for, institutional reform.

Have successive enlargements weakened the EU? Although the arrival of new members requires a period of ‘settling in’, it is often followed by the development of new policies and strengthening of the institutional framework. For example, the EU’s structural funds, and a more ambitious cohesion policy (see section 7.4.2) resulted from the accession of Greece, Portugal, and Spain: poorer countries requiring financial aid. Later, it was feared by other members that the accession of Austria, Sweden, and Finland—countries that had pursued neutrality or non-alliance—would undermine the EU’s emerging CFSP. In practice, however, these countries have viewed the development of the CFSP more favourably than some of the EU’s older members.

From time to time, older members complain that it was easier to take decisions when the EU had fewer member states. While increased size has complicated the processes of decision-making, successive increases in size have also allowed the EU to develop more substantial and effective policies overall, both internally and externally, than would have been possible with a smaller group. The process of widening has often accompanied, or even driven, a deepening of the relationship: adding more member states has not usually been detrimental to further integration in the EU.

9.1.2p. 214 Enlargement as soft power

The success of enlargement in helping to drive political and economic change in Central and East European (CEE) countries offers a good illustration of the EU’s ‘soft power’ (Nye 2004) or ‘external governance’ (Schimmelfennig and Sedelmeier 2004; Lavenex 2004). The EU’s external pressure through accession conditionality operated as a powerful transformative factor for policy-makers in those countries to pursue domestic reforms in the pre-accession period (Schimmelfennig and Sedelmeier 2005a, 2020; Vachudova 2005; Epstein and Jacoby 2014; Grabbe 2014; Börzel et al. 2017). As countries undergoing a post-communist transition, they were generally receptive to Western political and economic models, but needed sustained external assistance.

Conditionality was not employed in earlier enlargements. When the Commission proposed in 1975 that Greece’s membership should be preceded by a period of preparation, member states rejected the idea. In the 1990s, Austria, Sweden, and Finland, which already had a high degree of economic integration with the EU through a free trade agreement and EEA membership (Box 9.1), had been able to join swiftly after the Council decided to start accession negotiations. The principle of conditionality was developed for the countries of CEE, who expressed their intention to join after the end of the Cold War. Existing members were apprehensive that taking in so many new countries that had just emerged from communist authoritarian political systems and planned economies, without adequate preparation, could impair the EU. These concerns led the EU in 1993 to define general membership criteria when it agreed that the countries of CEE could in principle become new members, once these conditions were met.

These membership requirements (the ‘Copenhagen criteria’ as they were announced at a European Council meeting in Copenhagen—see Box 9.2) have become the standard template for EU enlargement. The criteria require a wide-ranging assessment of a country’s political, economic, and administrative standards that go further than any examination made by the EU of its existing members. Crucially, the membership criteria relate not only to a country’s ability to comply with the EU’s common rules and the body of EU law, as might have been expected. They also include key political criteria relating to democracy, human and minority rights, and good governance that go far beyond what the EU treaties demand of full members.

Box 9.2 Spotlight on: Criteria for membership

Treaty on European Union (TEU) Provisions

Article 49 (extract): Any European state which respects the values referred to in Article 2 and is committed to promoting them may apply to become a member of the Union … The conditions of eligibility agreed upon by the European Council shall be taken into account.

Article 2: The Union is founded on the values of respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities. These values are common to the member states in a society in which pluralism, non-discrimination, tolerance, justice, solidarity and equality between women and men prevail.

Copenhagen Criteria

The European Council at Copenhagen (1993) stated that membership requires that:

the candidate country has achieved stability of institutions guaranteeing democracy, the rule of law, human rights and respect for and protection of minorities;

a functioning market economy [exists] as well as the capacity to cope with competitive pressure and market forces within the Union;

the ability [exists] to take on the obligations of membership including adherence to the aims of political, economic and monetary union.

It added another criterion for enlargement:

The Union’s capacity to absorb new members, while maintaining the momentum of European integration, is also an important consideration in the general interest of both the Union and the candidate countries.

The fact that the EU’s accession conditionality sets standards for potential members that do not apply to member states can be viewed as a double standard. However, since the candidate countries (Box 9.1) usually have a more intense preference for accession than the existing members, the EU can use this leverage to promote domestic political reforms in candidates that the EU finds desirable. The EU might either find such reforms beneficial in their own right or to serve the EU’s political interests in stability and prosperity in its neighbourhood. In any case, the different treatment of would-be members is only temporary. After joining, an applicant country becomes a member and has a voice in EU decision-making and the p. 215EU loses the leverage that it had through conditionality during the pre-accession period. New member states can reverse conditionality-induced political changes because the treaties do not provide EU institutions with strong enforcement powers vis-à-vis the member states. One example of such a reversal is the ‘democratic backsliding’ in Hungary and Poland after accession (see section 6.4).

9.1.3 An institutional paradox

The enlargement process gives specific insights into the functioning of the EU’s institutions. The mode of operation for enlargement is essentially intergovernmental. The Council adopts all decisions on enlargement by unanimity. While majority voting in EU decision-making has been extended in many areas, no one has ever p. 216suggested extending it to enlargement. Accession negotiations take place in an IGC organized between the member states and the applicant state. The result is an Accession Treaty, signed and ratified by sovereign states.

The roles of the EP and the Commission in the process of enlargement are limited. The Parliament has the right to approve or reject enlargement, but only at the end of the negotiation process, when it votes on a yes/no basis without being able to modify the Accession Treaty. During accession negotiations, Parliament is informed regularly, but has no seat at the table.

The Commission’s status in accession negotiations is not the same as in external trade negotiations where it acts as negotiator (see section 8.3.1). In accession conferences, the Council presidency, rather than the Commission, presents EU positions, even on matters where the Commission has competence. Formally, the Commission is not the EU’s negotiator, although it may be mandated by the Council to ‘seek solutions’ with applicants. Nevertheless, in practice, the Commission plays an extremely influential role in the process of enlargement, exercising more influence over applicant countries than after they become members. The Commission’s influence stems from its role in monitoring the progress of applicant countries in respect of the criteria for EU membership; its annual ‘Regular Reports’ on each country provide the benchmarks (Box 9.1) for decisions on the conduct of enlargement. The Commission also presents proposals to the Council for ‘common positions’ to be taken by the EU side, and it is in a position to act as an intermediary with the applicant countries.

Within the Council, enlargement is handled in the General Affairs Council, rather than the Foreign Affairs Council. As a result, the high representative has no specific role in accession negotiations, other than being a member of the Commission. The fact that the Commission, not the EEAS, manages enlargement policy illustrates that it is not considered primarily one of foreign policy.

9.2 How the EU Has Expanded

The first applications for membership were made by the UK, Denmark, Ireland, and Norway in 1961–2, soon after the EC came into existence. The contested nature of enlargement was reflected in two vetoes of the UK’s accession by French President De Gaulle, but three of those four countries eventually joined in 1973: the UK, Denmark, and Ireland. Over time, the number of EU member states has quadrupled (see Table 9.1), its population has tripled, and its official languages have increased from four to twenty-four. The withdrawal of the UK has been the first deviation from the trend of an ever-expanding EU (see section 10.2). Otherwise, enlargement has been an almost permanent item on the EU’s agenda, and remains so today, with several countries either already in accession negotiations or having formally applied for membership (see Table 9.2).

Table 9.1 Chronology of enlargement

Application for membership

Opening of negotiations


United Kingdom




























































Czech Republic





























The UK, Denmark, and Ireland first applied in 1961, but negotiations ended in 1963 after France vetoed their admission. The UK withdrew from the EU in January 2020.

Norway applied twice (1967, 1992) and completed negotiations, but Norwegians twice said ‘No’ in referenda (1972, 1994).

Switzerland made an application in 1992 but suspended it in the same year after a ‘No’ in a referendum on the EEA.

Iceland made an application in 2009 and negotiations began in 2010, but were suspended in 2013 by its government.

In 1990 enlargement took place without accession when East Germany joined the German Federal Republic.

Table 9.2 Prospective members

Application for membership

Candidate status

Opening of negotiations





North Macedonia


















This list includes all countries considered by the EU to be in the accession process as of July 2021. When the EU decides that an applicant country has made sufficient progress, it may award it the status of ‘candidate’. Until then, it has the status of ‘potential candidate’, as Kosovo had at the time of writing (despite not being recognized as an independent state by some EU members).

p. 217Despite the large number of countries wishing to join, the path to membership is not easy. Conditionality requires extensive, and often demanding, domestic reforms before negotiations on accession can begin. Once begun, the negotiations are arduous (see Boxes 9.5 and 9.7): there is no guarantee that they will end in agreement, or by a certain date, and the bargaining is inevitably one-sided. The EU p. 218insists that applicant countries accept all its rules (known as the acquis), and allows delays in conforming to EU law in specific issue areas (‘transitional periods’) only in exceptional cases. Moreover, the member states themselves often insist on transition periods during which the new members will not fully enjoy the benefits of membership, for example, with regard to free movement of labour or receipts from the EU budget (see Schneider 2008). Yet new members generally accept even such asymmetric accession treaties on the basis that ultimately they will benefit more from being inside the EU rather than outside, arguably benefiting more from their EU membership than the existing members benefit from the accession. This asymmetry in the intensity of preferences for enlargement between the EU and candidate countries explains why the EU has much more bargaining power in accession negotiations (Moravcsik and Vachudova 2003). The EU has never invited others to join its club—in fact it has tended to discourage them. In this sense, the EU’s strategy for enlargement has been reactive rather than pro-active. The Union has grown because of its soft power attraction for neighbouring countries rather than as the result of an expansionist strategy.

9.2.1 Why countries want to join

The demand for accession reflects a mixture of self-interest and identity politics (Schimmelfennig and Sedelmeier 2002, 2005b). Countries apply to join the EU if they consider membership to be in their political and economic interest. In the case of the UK, its application was motivated by the prospective benefits of the common market for trade and economic growth. But its leaders also realized that the original six members were on the way to creating a European system from which the UK p. 219could not afford to be excluded politically. Ireland and Denmark, due to their close economic relations with the UK, tied their application to the UK’s. For the UK (and Denmark), the economic incentives trumped a long-standing wariness of European supranational integration with which it co-existed uneasily until the narrow rejection of EU membership in the 2016 referendum (see section 10.2).

Box 9.3 The path to membership

Start. A country submits an application for membership to the Council of the EU:


The Council considers whether the country satisfies the conditions of Article 49 (see Box 9.2)


The Council asks the Commission for an Opinion.


The Commission delivers its Opinion to the Council.


The Council confirms the applicant country’s status as a candidate.


The Council decides to open accession negotiations, conducted in an IGC between the EU member states and each applicant individually.


The Commission screens (Box 9.1) the (presently 35) chapters of the acquis with the applicant.


Individual chapters in the negotiations are opened when the Council decides that the applicant has met the relevant benchmarks (Box 9.1).


The applicant presents its position for that chapter; the Commission proposes a ‘common position’ of the EU, the Council approves it, and presents it to the applicant.


After agreement is reached on each chapter, it is closed when the EU decides that the applicant has met the relevant benchmarks.


When all chapters are closed, the EU and the applicant agree on a draft treaty of accession.


The Commission issues an opinion on the treaty.


The European Parliament gives its consent.


The member states and the applicant(s) sign the treaty.


The signatory states ratify the treaty according to their national procedures, which may include a referendum.

Finish. The treaty comes into force, and the applicant country becomes a member state.

The applications from Greece, Portugal, and Spain were made in different circumstances. After emerging from right-wing totalitarian regimes, these countries saw EU membership as a confirmation of their return to democracy. In contrast to the UK, identity politics—the sense of being accepted back into the European family of democracies—were an important driving force for accession, alongside the prospect of access to the common market and significant transfers from the budget.

p. 220When Austria, Sweden, and Finland applied for membership in the late 1980s and early 1990s, the balance of economic rationale and identity politics more closely mirrored the UK’s. Despite their longstanding reservations about European integration, these three countries applied in order to ensure unrestricted access to the newly created single market. The end of the Cold War had made redundant their traditions of neutrality, and thus domestic obstacles to EU membership were lifted. The Commission’s concerns that their purely economically motivated accession would become an obstacle to the politics entailed in further integration as well as foreign policy cooperation resulted in the creation of the EEA in 1994 as an alternative framework to membership, which also gave them access to the single market. Since the EEA still obliged Austria, Sweden, and Finland to accept EU rules without having a say in deciding them, the three countries never considered it more than a temporary step on their way to full EU membership. However, the EEA turned out to become precisely the mid-range option for Norway, which had at the time also been engaged in EU accession negotiations. In 1994, after its population voted narrowly against EU membership—repeating the result of its 1972 referendum—Norway considered the economic benefits of the single market (and the exclusion of agriculture and fisheries from the EEA) sufficiently beneficial to remain in the EEA (along with Iceland and Liechtenstein).

p. 221When the countries of CEE escaped from communism and Soviet domination, they turned to the EU for economic assistance and membership. Like Greece, Spain, and Portugal, they wanted to rejoin the European family and consolidate their return to democracy. For their transition from central planning to market economy, the EU’s standards offered a workable template. Uncertain of Russia’s future role, they also desired EU membership for security reasons, in addition to NATO membership, which they pursued at the same time (see Box 9.4).

Box 9.4 Spotlight on: A double race to membership in the EU and NATO?

After the end of the Cold War, most of the countries of CEE wanted to join NATO as well as the EU. NATO is a transatlantic alliance created in 1949 in the face of a perceived threat from the Soviet Union. Its members are committed to mutual assistance under Article 5 of the NATO Treaty, which says that ‘an armed attack against one or more of them in Europe or North America shall be considered an attack against them all’. NATO now has 30 members:

US, Canada,

Twenty-one EU states (all except Austria, Cyprus, Finland, Ireland, Malta, Sweden),

UK, Norway, Iceland, Turkey, Albania, Montenegro, North Macedonia.

Most other European states, including Russia and Sweden, have an association with NATO but are not full members.

For the countries of CEE, concerned about Russia’s future intentions, NATO offers hard security in the military sense, including its nuclear ‘umbrella’. In contrast, the EU offers soft security in the sense of membership of its political and economic union. For these countries NATO was easier to join than the EU because

NATO has less demanding membership requirements, mainly concerning the organization and equipment of troops,

NATO’s leading member, the US, pressed for its enlargement.

The result of the double enlargement is that the membership of the two organizations now largely overlaps, which makes it easier for them to work together. But the NATO/EU relationship is not simple, and there remains a basic asymmetry (see section 8.4). NATO, unlike the EU, includes the US. NATO has the military tools to deal with the results of insecurity, while the EU has the tools of civilian crisis management that can help address causes of insecurity via, for example, the promotion of economic integration and good governance.

9.2.2 When the EU decides to let countries in

As we saw in the initial applications of the UK, the EU does not always respond positively to accession requests. As with candidate countries applying for membership, EU member states are influenced by a combination of self-interest and identity politics when deciding whether to let an applicant country join (Schimmelfennig and Sedelmeier 2002). Moreover, since enlargement requires a unanimous decision in the Council, the member states least interested in enlargement generally determine whether, and under what conditions, accession takes place. On occasion, they also extract concessions from the new member states and from other member states that are keen to support enlargement.

Enlargement is generally considered beneficial to the EU, since it enlarges the Union’s market and increases the effectiveness of common policies. At the same time, a larger membership can make decision-making more difficult, especially if preferences among the member states become more diverse and difficult to manage. Increased numbers can also create problems for the sustainability of certain EU policies that require significant budgetary resources, such as agriculture or regional policy. In general, enlargement is therefore easier when candidate countries are rich, and when they are small (as was the case in 1995 with Austria, Finland, and Sweden). Wealthier countries tend to be net contributors to the EU budget rather than recipients of regional of cohesion funds. Bigger countries often have the advantage of more significant markets but, if they are poor and/or have a large agricultural sector, they put more pressure on the EU’s budget and/or the CAP than smaller countries. Apart from these more general factors, specific characteristics of a candidate country may prompt opposition to their accession in individual member p. 222states. Typically this relates to economic competition in import-sensitive sectors, such as the concerns of French farmers about Spanish agricultural products, which prolonged Spain’s accession negotiations significantly.

Apart from member states’ consideration of how a country’s accession affects their material self-interest, considerations of political and national identity also play a role, both as a driving force and as an impediment to enlargement. For example, identity arguably played a role when French President De Gaulle vetoed the UK’s application in the 1960s. Not only had the UK’s identity, which conceived of national sovereignty as incompatible with European integration, been a factor contributing to the initial decision not to participate in the creation of the EEC. The notion of incompatible identities was also a concern for the French government. Although De Gaulle did not have a federalist vision of European integration himself, he nevertheless considered the UK’s strong Atlanticist identity to be at odds with membership. Conversely, arguments about Greece as a cradle of European civilization—articulated by the then French President Giscard d’Estaing—helped to convince other member states to overrule the Commission’s negative opinion on Greek membership.

The case of Eastern enlargement presents a particularly interesting example of the role of identity politics. Some existing member states had to fear net material costs from enlargement. The new members made significant concessions during the accession negotiations, concessions that reduced the costs of enlargement for the existing member states (Schneider 2008). These concessions—in particular with regard to the free movement of workers, and receipts from the CAP and regional funds—delayed the new members’ full enjoyment of membership rights. However, by merely delaying benefits for the new members, such concessions only temporarily reduced the costs of enlargement for existing member states. Those concessions therefore cannot fully explain why there was no veto from member states such as Portugal, Spain, or Ireland—that compete with the newer Eastern members for agricultural and regional funds—and where geographical distance greatly reduces both the economic opportunities of enlargement and the risks of non-enlargement. One explanation is that the EU’s pan-European identity and rhetoric of reuniting the continent in a community of democracies served as a constraint on openly self-interested opposition to enlargement. Many governments were reluctant about enlargement but felt that they could not legitimately object to a policy to which they had rhetorically committed themselves (Schimmelfennig 2003; Sedelmeier 2005). Since the Eastern enlargements have been the most challenging so far, they deserve a more detailed discussion.

9.2.3 Recent enlargements

The disintegration of the Soviet bloc in 1989 was a seismic shock, creating risks of political, financial, and even security instability in Europe. Civil war broke out in ex-Yugoslavia, and such strife could have occurred elsewhere if events had unfolded p. 223differently. The countries of CEE, however, succeeded in charting a route towards democracy, stability, and prosperity by making far-reaching economic, social, and political reforms. The prospect of EU membership served to guide them through a peaceful regime change in which the process of Europeanization—the domestic adaptation to the EU’s rules, norms, and policies—played a key role (see Box 4.2; and Vachudova 2005, Schimmelfennig and Sedelmeier 2005a, Sedelmeier 2011, Grabbe 2014, Epstein and Jacoby 2014).

Faced in the early 1990s by many new aspirants for membership, the EU responded cautiously. At first, it concluded a series of ‘Europe Agreements’ on aid, trade, and foreign policy consultations with countries of CEE, initially refusing to promise membership. At the Copenhagen summit in 1993, the Union eventually accepted that these countries could join, but only after they had fulfilled the ‘Copenhagen criteria’ for membership (see Box 9.2).

EU accession negotiations opened with the first six countries in 1998 and six more in 2000 (including Cyprus and Malta as non-post-communist countries), reflecting differences in the pace of alignment with EU requirements (see Box 9.5). The main controversies in the negotiations were:

free movement of labour: the EU allowed old members to maintain restrictions on workers from new member states for up to seven years;

agricultural policy: the EU insisted on a period of 12 years for introducing direct payments to farmers in the new member states; and

regional funds and cohesion policy: the EU restricted the initial level of payments to the new, much poorer, members (see Avery 2004).

Box 9.5 How it really works: Joining the EU individually or together

Although enlargement may involve a single country (as in the cases of Greece and Croatia), the EU usually prefers to have a group of countries joining in a single wave of accession. Even when the EU negotiates with a group of countries at the same time, each accession negotiation is separate. The EU insists that it treats each applicant country on its own merit, according to the principle of ‘differentiation’: the path to membership depends on individual progress in meeting the criteria. Differentiation also allows the EU to create competition between applicant countries that puts pressure on individual candidates to accept concessions made by other candidates for fear of being left behind. Such competition further increases the asymmetric nature of accession negotiations, in which the EU is in a far stronger bargaining position. It helped to push the CEE countries towards membership together in 2004, despite significant obstacles in the negotiations, and on terms that were highly favourable to the existing member states.

Applicants often demand a target date for membership. But the EU does not concede that until the end of negotiations, since the promise of a date weakens the conditionality of the process.

p. 224The enlargement to CEE was an extraordinary episode in the history of European integration, and it shifted the EU’s scale of activity to a continental level. Eastern enlargement helped the transition both to democracy and market economies in post-Communist states and united a Europe divided during the Cold War between East and West. In awarding the Peace Prize to the EU in 2012, the Norwegian Nobel Committee cited enlargement, declaring that it had ‘helped to transform most of Europe from a continent of war to a continent of peace’.

However, despite its many successes, Eastern enlargement has also contributed to a marked cooling in the EU towards further enlargements—an ‘enlargement fatigue’. With the enlargements of 2004 and 2007 and the financial crisis of 2008, the question of ‘absorption capacity’ (Box 9.1) once again became an element in the debate. This concept of absorption capacity, first introduced at Copenhagen in 1993 (see Box 9.2), is vague but refers to the need to ensure that enlargement as a process does not jeopardize the EU’s ability to ‘maintain the momentum of European integration’. However, the claim of the EU having a limited absorption capacity is also a convenient argument for a range of anxieties about enlargement present among many member state governments.

Public opinion, particularly among the older member states, is more resistant to enlargement, which is often blamed for, or exacerbates, problems arising from other causes such as globalization or government cuts to public services. In particular the influx of workers from the newer member states has been perceived as causing social problems in some of the older member states. Populist parties have increasingly tapped into, and galvanized, domestic opposition to enlargement. This domestic opposition has not only made the member state governments more cautious about supporting enlargement in the first place, but may also lead governments to hold national referenda to ratify future accession treaties (as France did when the UK joined).

Apart from public concerns about enlargement, member state governments have become increasingly concerned about governance problems in the new members. The persistence of corruption, maladministration, and weak judiciaries, especially in Bulgaria and Romania, both of which joined in 2007, led to a widespread perception in the EU that their accession had been premature. In addition, ‘democratic backsliding’—a serious deterioration of democracy (see section 6.4)—most notably in Hungary and Poland, has intensified calls to apply the accession criteria more rigorously. One result was the EU’s ‘New Approach’ to accession negotiations in 2012, under which the chapters on fundamental rights, justice, freedom, and security are treated as a priority. Another result was that the Commission agreed to a change in the enlargement process in 2020, which gives the member states more control, including the possibility to suspend accession negotiations altogether.

More generally, the EU’s more cautious approach to enlargement has led to a weakening of membership prospects for current candidate countries. The decreased credibility of the incentive of membership—that candidate countries are not sure if the EU will accept them even if they have met all the accession criteria—has p. 225triggered a vicious circle (Schimmelfennig and Sedelmeier 2020). The EU has lost a degree of leverage over domestic reforms through accession conditionality, and a subsequent slowdown and even reversal of domestic reforms in candidate countries have in turn rendered the prospect of membership more remote. How the EU’s waning commitment to enlargement has affected the accession prospects of individual candidates varies depending on a range of domestic factors both in existing EU member states and in prospective members.

9.3 Prospective Members and Wider Europe

The EU officially considers several countries as prospective members: Turkey and the Western Balkan countries. Others—Iceland, Norway, and Switzerland—have applied for membership in the past but no longer pursue accession. Although the treaty says that ‘any European state’ may apply to become a member (see Box 9.2), other European countries are at present discouraged from applying, including some successor states of the Soviet Union that are subject to the EU’s Eastern Partnership (EaP; see section 9.3.4).

9.3.1 Norway, Switzerland, and Iceland

It is sometimes forgotten that membership applications have been made by Norway, Switzerland, and Iceland (see Table 9.1). Oil-rich Norway negotiated and signed Accession Treaties, first in 1972 and then again in 1994, but it did not join on either occasion after its people had voted ‘No’ twice in referenda. This divisive experience has made its politicians reluctant to reopen the question of EU membership. As a member of the EEA it has access to the single market and participates in other EU policies in return for following EU single market rules. The EEA is the closest form of relationship that the Union has ever made with non-member countries.

In Switzerland, the French-speaking part of the population is broadly more favourable to EU membership than the German-speaking part. Switzerland’s application for EU membership was suspended when its citizens voted 50.3 per cent ‘No’ to joining (what eventually became) the EEA in a referendum in 1992. Since then, Switzerland has pursued its interests through a series of bilateral agreements with the EU. Attempts by the EU from 2014 to replace the patchwork of 120 individual agreements with an overarching framework agreement failed after the Swiss government pulled out of negotiations in May 2021, in particular over issues of access to the Swiss labour market. As the EU insists that it will not renew existing bilateral agreements without a framework agreement, Switzerland’s privileged access to the single market is starting to unravel.

Iceland, as a member of the EEA, decided to apply for EU membership in 2009 after the banking crisis triggered by the 2008 global financial crisis showed its vulnerability as a small country (see Avery et al. 2011). Accession negotiations began p. 226in 2010, but were suspended by Iceland’s new government in 2013, even before discussions began on the EU’s common fisheries policy, the main obstacle to membership for Iceland.

While EU accession is therefore currently not on the agenda of any of these three countries, small, rich countries like these easily fulfil the conditions for membership and are thus ideal applicants for the EU. If they decided to apply again, they would be accepted readily as candidates.

9.3.2 Balkan countries

In Southeast Europe about 18 million people remain outside the EU:1

Albania: 2.9 million

Bosnia-Herzegovina: 3.5 million

North Macedonia: 2.1 million

Kosovo: 1.8 million

Montenegro: 0.6 million

Serbia: 7 million.

Figure 9.1 The expanding European Union

A glance at the map (Figure 9.1) shows that the EU surrounds these countries—known as the Western Balkans. They are at different stages on their way to potential EU membership (see Table 9.2). At a summit at Thessaloniki in 2003, the EU’s p. 227leaders recognized all the countries of the Western Balkans as prospective members, and the Union now provides financial and technical help through its pre-accession programmes.

These countries are trying to make the political and economic reforms necessary to join the EU, but have—to varying degrees—difficult legacies of communism, ethnic conflict, and recent statehood. With the exception of Albania, for most of the 20th century the region was united in Yugoslavia. The disintegration of the Yugoslav federation in the 1990s led to civil war and ethnic conflict especially in Bosnia and in Kosovo, then part of Serbia. The conflicts were eventually ended through interventions by the UN and NATO, but problems of contested frontiers, interethnic tensions, and fragile statehood persist. The question of Kosovo’s international status is not fully resolved, with its independence from Serbia not recognized by all EU members. An EU Rule of Law Mission (EULEX) monitors Kosovo’s domestic institutions. Bosnia is still under external tutelage: a UN high representative, who was initially also the EU special representative (until 2011, when the latter position was fused with the head of the EU Delegation), supervises the implementation of the Dayton peace agreement. Coupled with problems of poor governance, corruption, and crime, the region suffers from political dependency on external actors. But domestic reforms, and EU membership itself, require autonomy and a functioning democracy.

The region poses the biggest test yet of the EU’s transformative power. Can conditionality and pre-accession instruments be used as successfully as they were in Central Europe? Given the more difficult legacies that make adjusting to EU conditionality more demanding, and often politically contentious, the decreasing credibility of the membership promise makes it less likely that the EU can encourage good governance and reconciliation between communities. Although Croatia succeeded in joining the EU in 2013, and Serbia has begun to normalize its relations with Kosovo and started accession negotiations, as has Montenegro, the signs are not encouraging. A general backsliding has occurred in democratic and good governance.

The link between backsliding and the declining credibility of the membership prospect was most notable in North Macedonia, which the Commission repeatedly recommended for accession negotiations after 2009, only to see them blocked by Greece over the dispute about the country’s name. Even after eventually agreeing to a domestically contentious compromise with Greece in 2018, and despite recommendations by the Commission to open accession negotiations, the Council still repeatedly postponed a decision. It finally gave the green light in 2020 after the Commission ceded to French pressure to adjust the enlargement process to give the member states more control over the negotiation process, including the possibility to halt negotiations in certain areas, or to suspend negotiations altogether. Yet in a further twist, the Bulgarian government blocked the opening of negotiations as it objected to North Macedonian interpretations about their shared history and language (with North Macedonia claiming that Macedonian is a separate language, while Bulgaria insists that it is merely a dialect of Bulgarian).

p. 228Apart from the limitations on the EU’s effective use of membership conditionality in the region, the EU has experienced significant internal discord among member states about relations with specific potential candidates. Internal discord has been most pronounced over Kosovo’s unilateral declaration of independence from Serbia. Five member states have not recognized Kosovo’s statehood: Romania, Slovakia, Spain, and Cyprus—who have geographically concentrated ethnical minorities that may, or already do, pursue independence—and Greece, in support of Cyprus. Such internal division has also complicated the EU’s ability to have a coherent external policy in the region, where it is increasingly engaged in geopolitical competition with Russia and China (see Box 8.5). Russia has historically close relations with Serbia, while relations with Russia are a highly divisive issue in Montenegro. China has invested heavily in the region as part of its Belt and Road initiative, with the financial pressure of repaying loans making countries like Montenegro vulnerable to Chinese influence. China has also sought to pursue relations with the Western Balkans and the Central and Eastern EU members in a separate institutional framework (‘17+1’), which has been viewed as a deliberately divisive strategy by other EU member states. In turn, the increasing salience of geopolitics in the region has further undermined the consistency and credibility of EU conditionality: the EU has become more tolerant of governments that become more autocratic as long as they continue to pursue a Western orientation for their country and claim to secure stability in the region (Bieber 2018).

9.3.3 Turkey

Turkey’s ‘European vocation’ was proclaimed as early as 1964 in its Association Agreement with the EC. Its application for membership dates from 1987. But the path towards membership has been long, and remains difficult (see Aydın-Düzgit and Tocci 2015). Despite the fact that accession negotiations opened in 2005, an increasingly autocratic turn in Turkey since President Recep Tayyip Erdogˇan and his Justice and Development Party (AKP) came to power makes Turkey’s membership currently a distant prospect.

Many of the arguments that were valid for preceding enlargements apply to Turkey. Turkey is a big country (its population of 84 million would make it the largest member state) and, in terms of GDP per capita, poorer than the EU average (Turkey’s GDP per capita in current US dollars in 2019 was $9,126 while it was $47,828 for the EU).2 Although this would create costs for the EU’s budget in agriculture and cohesion policy, the overall economic impact of Turkey’s accession should be positive (see Barysch et al. 2005). Its impressive economic growth in the decade after 2000, and its young labour force, would bring benefits to the single market. Its position on Europe’s Southeastern flank gives it geostrategic importance in relation to the Middle East and the Black Sea region; being in NATO, and p. 229with the biggest army of NATO’s European members, it has a key role in European security (see Tocci 2011).

Although Turkey’s membership offers benefits for the EU in terms of foreign policy, it would also bring new risks. With Turkey’s accession, the EU’s external frontiers would extend to Azerbaijan, Armenia, Iran, Iraq, and Syria, bringing it into direct contact with regions of instability. Moreover, Turkish foreign policy has become increasingly at odds with the EU’s, such as Turkey’s military intervention in Syria, and its backing of Azerbaijan during the fighting in the Nagorno-Karabakh conflict in late 2020. In 2019, the EU adopted sanctions—a travel ban and asset freeze—against individuals involved in Turkey’s drilling for natural gas in disputed Eastern Mediterranean waters also claimed by Greece and Cyprus.

The EU has closely monitored Turkey’s efforts to conform to European standards of democracy, human rights, and rule of law. Especially between 1998 and 2005, progress was made towards meeting the Copenhagen criteria, although remaining problems included Turkey’s treatment of its Kurdish minority, and its restrictions on freedom of speech and of the press. The increasingly autocratic turn under President Erdoğan and the AKP, especially after a thwarted coup in 2016, has led to major steps backwards on the EU’s political conditions for democracy and human rights (see Yılmaz 2021). Although the AKP government remains officially committed to EU membership, it no longer appears a serious goal.

Even before this deterioration in relations, Turkish membership had always been highly contested in the EU. Public opinion in the EU is very negative, influenced by fear of an influx of Turkish migrant workers but also by identity-related factors (Toshkov et al. 2014): the idea that Turkey is different and not European in geographical or cultural terms. Turkey’s difference is often linked in political discourse to the majority of Turkey’s population being Muslim, but it has been a secular state since the 1930s. In turn, negative public opinion has resulted in an opposition to Turkish membership from mainstream political parties in France, Germany, and Austria (among others).

Cyprus is a further thorn of contention. Since Turkey intervened militarily in 1974, the Turkish Republic of Northern Cyprus—not recognized by the rest of the international community—has been separated from the south. Hopes of reuniting the two parts of the island were dashed in 2003 when the Greek Cypriots in the south voted against a UN plan that was accepted by the North. As a result, the enlargement of 2004 brought a divided island into the EU. Turkey’s refusal to recognize the Republic of Cyprus has also prevented it from implementing the Customs Union between the EU and Turkey in Cyprus, which has created further problems for EU-Turkey relations. President Erdogˇan reignited tensions in November 2020 by calling for a ‘two-state solution’ instead of the federal solution supported by the EU and the UN.

The refugee crisis of 2015 led to an agreement between the EU and Turkey in March 2016 that aimed to curb migration flows into the EU through Turkey (see section 7.5.3). Under the agreement, the EU offers significant funding to Turkey p. 230for accepting a return of migrants arriving in the EU from Turkey. The EU’s dependence on Turkey’s cooperation on migration has increased Ankara’s bargaining power in relations with the EU. However, while it may have muted the EU’s criticism of Turkey’s record on human rights, so far, the Turkish government has not shown much interest in using its leverage to advance its accession prospects.

The deterioration of democracy and human rights in Turkey, public opposition inside the EU, and continued strained relations with Cyprus have put a serious question mark over Turkey’s bid for EU membership. Although accession negotiations formally continue, progress has been slow and several chapters are blocked by objections from France and Cyprus. Given domestic opposition to Turkish membership, some member state governments would not be unhappy if the deterioration of democracy and declining interest in EU membership in Turkey make Turkish accession a distant prospect. Yet the diminishing prospect of membership means that the EU’s ability to influence domestic developments in Turkey is also greatly diminished.

9.3.4 Eastern European countries in the Eastern Partnership

With its expansion to CEE, the EU gained a series of new neighbours to the east. It already had a Euro-Mediterranean Partnership with countries to the south, and was obliged to rethink its relations with the countries of Eastern Europe that were formerly in the Soviet Union. Newer EU members such as Poland and Hungary did not want to see their accession lead to the erection of new barriers to countries with which they had cultural, social, and economic links. Their attempt to create an institutional framework raised concerns among the Southern EU members that a stronger focus on Eastern Europe would downgrade relations with the Southern neighbours. The resulting compromise was the creation of the European Neighbourhood Policy (ENP) in 2003, covering sixteen countries in both the EU’s Southern and Eastern neighbourhood: Morocco, Algeria, Tunisia, Libya, Egypt, Israel, Jordan, the Palestinian Authority, Lebanon, and Syria in the south; and Armenia, Azerbaijan, Georgia, Moldova, Ukraine, and Belarus in the east (see Figure 9.2).

Figure 9.2 The European Union’s Neighbourhood Policy

The ENP’s aim was to extend stability, prosperity, and security, and to create a ‘ring of friends’ by developing political links and economic integration with the EU. Its main instrument is a series of Action Plans negotiated with each partner country and backed by financial and technical assistance. These plans cover political dialogue, economic and social reform, trade, cooperation in justice and security, transport, energy, environment, education, and so on. They require the neighbours to adopt and implement European regulations and a large part of the acquis: the system is modelled on the EU’s Accession Partnerships with future members (Kelley 2006). In this sense, the ENP seeks to replicate the success of the EU’s accession conditionality. Indeed, some member states would like to see the ENP as a form of ‘enlargement-lite’ (Hadfield 2009) or ‘conditionality-lite’ (Sasse 2008) that keeps the EU’s options open.

p. 231Crucially, however, the ENP lacks the big incentive of the enlargement process: the ‘golden carrot’ of EU membership. The absence of membership is unsurprising for the Southern neighbours in the ENP, as they do not meet the geographical criterion that candidates need to be European countries. Yet even for the Eastern European states in the ENP, such as Ukraine, the EU has insisted that the policy is ‘accession-neutral’. Removing this crucial incentive, even if it would have been anyway rather distant, has been a disappointment to the countries concerned and is arguably a serious flaw in EU policy towards them (see also Börzel and Lebanidze 2017; Börzel and Schimmelfennig 2017; Toshkov et al. 2021).

The EU acknowledged that the situation and interests of the Eastern countries in the ENP differed from those in the south through the creation in 2009 of the EaP with Armenia, Azerbaijan, Belarus, Georgia, Moldova, and Ukraine. The EaP resulted from an initiative by Poland and Sweden, in response to a separate p. 232French attempt to deepen relations with the countries making up the EU’s Southern neighbourhood through the creation in 2008 of the ‘Union for the Mediterranean’. Although the EaP offers improved political cooperation, economic integration, and increased financial assistance, in practice, it does not add much additional incentive for domestic reforms. The main innovation is the conclusion of Association Agreements—which in the past have been precursors to the accession process—and visa facilitation. But accession remains off the table. The EaP has had limited success in promoting democracy, good governance, and prosperity in Eastern Europe. Although the EaP offers financial aid and long-term benefits, it demands reforms that are too costly for the governments concerned, certainly without the incentive of EU membership (Toshkov et al. 2021). Most notably, the EU has had little impact on Belarus’s autocratic regime, which has been repeatedly a target of EU sanctions during President Alexander Lukashenko’s rule since 1994. Relations reached a new low after the brutal crackdown on mass protests against fraud in the 2020 presidential elections.

Nevertheless, the EU continues to be attractive to EaP countries: the decision of Ukraine’s President Viktor Yanukovych at the end of 2013 to pursue closer ties with Russia, rather than an Association Agreement with the EU, led to public protests and civil unrest that culminated in the fall of Yanukovych’s government. Russia responded with the annexation of Crimea and military support of dissidents in eastern Ukraine, which ended government control over these regions and created another ‘frozen conflict’. The EU has supported Ukraine primarily diplomatically, through imposing sanctions on Russia, and by providing financial assistance, including both humanitarian aid relating to the conflict as well as support for economic and governance reforms. Specifically related to the conflict in eastern Ukraine, the EU has launched the EU Advisory Mission for Civilian Security Sector Reform in Ukraine under the CSDP. It has also provided support for the OSCE Special Monitoring Mission, assistance to populations displaced or affected by the conflict, and to the restoration of governance and reconciliation. However, the EU still declined to put membership for Ukraine on the table.

The region remains one where the EU and Russia are engaged in a competition for influence. Russia fears that closer relations with the EU may lead to former Soviet countries joining NATO. The adoption of European standards of governance are seen by Russia as a threat to its own political and economic system. Russia has therefore used both positive and negative incentives to undermine EU influence in its ‘near abroad’. Armenia withdrew from negotiations for an Association Agreement in order to join Russia’s Eurasian Economic Union (although it then signed a new Partnership Agreement with the EU in 2017). Russia’s invasion of Georgia in 2008, in response to an attempt by Georgian forces to reassert control over its Russian-backed separatist regions Abkhazia and South-Ossetia, and Russian covert actions in eastern Ukraine in 2014 have shown that it is prepared to use force to destabilize its neighbours who orient themselves towards the West.

9.4p. 233 What Limits for EU Expansion?

The EU has used the prospect of membership successfully to enhance stability and prosperity in neighbouring countries. Its reluctance to offer membership unequivocally, even once its conditions are met, has limited its ability to do so in Southeastern Europe and post-Soviet Eastern Europe. Does the EU have to decide how far its expansion can continue and where its final frontiers lie? The EU already has different frontiers for different policies, as is the case for the euro and Schengen. In this sense, the EU is already a multi-frontier system. But problems arise as some perceive differentiated integration as leading to an exclusionist ‘core-group’. All members, and all applicants, want full rights in decision-making; there is no market for ‘second-class’ membership.

The founding EU treaties say that ‘any European state may apply to become a member’ (subsequent treaties have added a reference to the liberal democratic values listed in Article 2 TEU; see Box 9.2). But what are the geographical limits of the European continent? To the north, west, and south, seas and oceans define it, but to the east there is no clear boundary. Although the Ural Mountains and Caspian Sea are often invoked as natural frontiers, some geographers consider Europe as the western peninsula of the Asian landmass—a subcontinent rather than a continent.

In any case, different geographical, political, and cultural concepts of Europe have prevailed at different times. Asia Minor and Northern Africa were within the political and economic area of the Roman Empire, but much of today’s EU was outside it. Other historical periods are cited as characterizing Europe in cultural terms, such as the experience of the Renaissance or the Enlightenment. It is sometimes suggested that the EU is based on shared liberal democratic values specified in Article 2 rather than geography. But if this argument were correct, we would expect like-minded states in distant parts of the world—such as New Zealand—to be considered as future members. While the emphasis on identity is important, what a ‘European identity’ entails is contested. For some, Christianity is a defining element of European identity. Yet the drafters of the Constitutional Treaty explicitly rejected a Polish proposal for a reference to God in its preamble. All these examples show how difficult it is to arrive at an agreed definition. The European Commission (1992) has taken the view that

[t]he term ‘European’ has not been officially defined. It combines geographical, historical and cultural elements which all contribute to the European identity. The shared experience of proximity, ideas, values and historical interaction cannot be condensed into a simple formula, and is subject to review by each succeeding generation. It is neither possible nor opportune to establish now the frontiers of the European Union, whose contours will be shaped over many years to come.

One way to establish which countries are considered European is to look at the CoE, founded in 1949 before the creation of the EC. It has a wider membership than the EU and thus provides an indication of the limits of Europe. All EU members are members of the CoE, and can hardly refuse to consider other signatories as p. 234‘European’. This suggests the following list of potential members of the EU (including two states not currently CoE members*):

Albania, Bosnia-Herzegovina, Kosovo*, North Macedonia, Montenegro, Serbia,


Iceland, Norway, Switzerland, UK,

Armenia, Azerbaijan, Belarus*, Georgia, Moldova, Ukraine,


Of this list of 18, the EU already considers some as potential members. Could it eventually embrace all the others? Could the final limits of the EU be set at 45 countries? That is unlikely: no state is obliged to apply, and the EU is not obliged to accept applicants. Meanwhile states may leave the EU, as the UK did in 2020. And new states may be created, for example if secessionist movements in Catalonia or Scotland obtained independence. In any case, an attempt by the EU institutions to decide the ultimate limits in advance would not give a clear answer. Such a decision would require unanimity, and existing member states have differing views on future membership. Those sharing borders with non-members often wish to bring them into the EU for reasons of stability and security, as well as for the economic opportunities. Poland, for example, wants its neighbour Ukraine to be a member of the EU. But others such as France are more restrictive, especially on the inclusion of Turkey. In fact, a discussion of the ‘limits of Europe’ can easily become a debate on ‘should Turkey join?’

What are the prospects for countries such as Ukraine, which are presently in the framework of the EaP? They are far from meeting the Copenhagen criteria, and EU membership is unrealistic for them for many years. But Russia’s actions in Ukraine have driven it towards the West for political support and financial assistance. Such actions have also strengthened the case for using the leverage of prospective EU membership to encourage the long-term reforms needed to rebuild the Ukrainian state and economy. Prudence argues for keeping open the prospect of EU enlargement to all European states. Aspirant countries can modify their behaviour significantly in the hope of obtaining membership. To define the EU’s ultimate borders now would demotivate those states that were excluded, and diminish the EU’s leverage over those included. Thus a strategy of ‘constructive ambiguity’ is likely to prevail in the EU’s enlargement policy.

Finally, what of Russia? It too is a European country, but its geographic expanse and population of 146 million mean that Russia joining the EU would be more like the EU joining Russia. Most crucially, its political trajectory in recent years has moved it away from European values, not towards them.

9.5 Evaluating Enlargement

Has enlargement been a success story for the EU? At the beginning of this chapter, we explored how enlargement is not only foreign policy but also a constitutive policy, in the sense that each accession reconfigures the EU’s composition. What are the p. 235essential criteria for evaluating the success of enlargement policy? The evaluation arguably needs to be two-fold: applying first to the period before enlargement—the ‘pre-accession’ period when an applicant country has been recognized as a ‘candidate country’ and is subject to accession conditionality—and, second, to the period after accession, when candidate countries have become members of the EU.

The criteria for the pre-accession period are similar to those for foreign policy: enlargement policy is successful if it enhances security, stability, and prosperity for the EU and for the neighbouring countries concerned, and if the EU can promote domestic democratic and good governance reforms in candidate countries. In this respect, enlargement policy was more successful with regard to the new members that joined between 2004 and 2013 than with current candidates and countries in the EaP (Börzel and Schimmelfennig 2017; Schimmelfennig and Sedelmeier 2020).

An equally important test of enlargement policy concerns the period after accession. Here the conditions for a successful result may be defined as the harmonious integration of new members (without disrupting existing members or the functioning of the EU’s institutions and policies), a continuation and sustainability of pre-accession reforms, and the satisfactory continuation of the EU’s development. Since there is no general agreement on the last criterion (what is a satisfactory development of the EU?), it is not surprising that evaluations often depend on pre-existing attitudes about the desirability both of enlargement and of European integration.

Focusing on the impact of enlargement on decision-making, the increase from 15 to 28 (now 27) has not, as feared, paralysed the EU’s decision-making, which seems to work as well, or as badly, as it did in the past (Best et al. 2008). Recent data show that enlargement had a rather limited impact on the EU’s capacity to produce legislation, although it is extremely hard to disentangle the impact of enlargement from other developments (Toshkov 2017). Nor has it led to an increase in ‘variable geometry’ (Box 9.1) within the EU, with more fields of policy having different memberships, as some commentators predicted (Schimmelfennig and Winzen 2017). Most new members, unlike some old members, have joined the Schengen system, and many of them have joined the euro.

By contrast, an assessment of the sustainability of pre-accession reforms and commitments after accession raises concerns. On the positive side, enlargement has not led to an increase of non-compliance with EU law (Börzel and Sedelmeier 2017). With the exception of the Southern enlargement, new member states generally comply better with the acquis than older member states. This result is particularly the case for the Eastern enlargement (Sedelmeier 2008) and confounded widespread concerns during the pre-accession period. However, this positive picture changes if we consider developments in areas covered by political criteria for accession. A deterioration of the quality of democracy and good governance is noticeable across CEE states (Vachudova 2009; Börzel and Schimmelfennig 2017; Schimmelfennig and Sedelmeier 2020).

Most alarming is the fundamental challenge to pluralism and liberal democracy in Hungary and Poland. In both countries, the government has used a parliamentary p. 236(super-)majority to concentrate power, to eliminate checks and balances by controlling the judiciary and the media, and to stifle electoral competition (see section 6.4). Although Article 7 TEU gives the EU the possibility to sanction countries that breach the values of Article 2 TEU, it requires unanimity (with the exception of the offending state) in the Council. EU institutions have had little influence on redressing democratic backsliding (Sedelmeier 2014; Pech and Scheppele 2017). However, they have been more vocal in their criticism of Poland—where the party in government is not a member of the EPP, the European association of centre-right parties—than of Hungary, where the governing Fidesz party was sheltered from criticism by the EPP, of which it was a member until 2021 (Sedelmeier 2016; Kelemen 2017).

9.6 Leaving and Joining

States may leave the EU as well as join it. In June 2016, a referendum on EU membership in the UK resulted in a narrow majority for leaving the EU (see section 10.2). The UK formally withdrew in January 2020. The difficulties in negotiating a withdrawal treaty and in its implementation demonstrate the difficulties and high costs involved in disentangling integration. At the same, the debates about the future relationship between the UK and the EU mirror some of the debates about the appropriate institutional framework for relations between the EU and different sets of candidate countries at different points in time—from participation in the internal market through the EEA to much more limited cooperation through Trade and Cooperation Agreements. As the costs of the ‘hard’ Brexit that the UK government chose in the Withdrawal Agreement become more tangible for businesses and voters, calls for a change in the institutional framework for EU-UK relations may again enter the political agenda.

Even before Brexit, the frontiers of the EU had already changed for reasons other than accession. On the one hand, parts of the territories of member states have gained independence or autonomy and have chosen not to remain in the EU: Algeria from France in 1962, Greenland from Denmark in the 1980s. On the other hand, when East Germany (not a member state of the EU) and West Germany (a founding member state) reunified in 1990, 16 million East Germans joined the EU. A similar territorial enlargement is perhaps conceivable in the case of Moldova reuniting with Romania or Northern Ireland voting to join Ireland. National independence movements, which have made gains in Catalonia, Flanders, and elsewhere, pose a question for which the EU has no precedent: the division of one of its member states into two states, both of which wish to remain in the EU. The EU treaty is silent on this question, and the Union itself has no explicit policy for such cases other than to respect the constitutional arrangements of its member states. However, it is clear that EU membership would not be automatic for a newly independent state: amendment of the treaty, requiring unanimity, would be needed (Kenealy 2014).

9.7p. 237 Conclusion

The expansion of the EU has been remarkable in its scope and impact. But after increasing its membership from 12 to 28 states and its population by a third in the period from 1995 to 2013, the EU will expand more slowly in future and has experienced the first withdrawal of a member state. In the medium term, the EU will limit expansion to countries of the Balkans, and possibly to Turkey, whose accession is currently a very distant prospect. In the longer term, the EU may eventually accept other East European countries such as Ukraine. But in the meantime they remain in the framework of its Neighbourhood Policy. The final limits of the Union will depend on developments in current members as well as in would-be new members and are likely to result from incremental political decisions, rather than from a long-term strategy.

Discussion Questions


Has the EU’s enlargement weakened its capacity for effective action? Has ‘widening’ stopped ‘deepening’?


Turkey’s application for membership dates from 1987: why is it so difficult for the EU to handle?


The EU’s treaty says ‘any European state may apply for membership’. Should the EU try to decide where its frontiers would ultimately lie?


The Neighbourhood Policy aims at creating a ‘ring of friendly countries’. Can it ever be a substitute for joining the EU?


Do explanations for why countries want to join the EU also help us to understand why a country might decide to withdraw from the EU?

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Further Reading

Schimmelfennig and Sedelmeier (2005b) present a theoretical framework for explaining enlargement. Preston (1997) gives an overview of different enlargement rounds up to the Eastern enlargement, and for the evolution of the Eastern enlargement of 2004, see Sedelmeier (2005). For conditionality and ‘Europeanization’, see Schimmelfennig and Sedelmeier (2005a) and Vachudova (2005). For more recent reappraisals of conditionality, see Epstein and Sedelmeier (2009), Gateva (2015), and Schimmelfennig and Sedelmeier (2020); and of the EU’s enlargement policy, see Börzel et al. (2017). On the EU’s relations with Turkey, see Aydın-Düzgit and Tocci (2015), and for a comprehensive overview of the Neighbourhood Policy, see Schumacher et al. (2018).

  • Aydın-Düzgit, S., and Tocci, N. (2015) Turkey and the European Union (London: Palgrave).
  • p. 238Börzel, T., Dimitrova, A., and Schimmelfennig, F. (2017) (eds.) ‘European Union enlargement and integration capacity’, Special issue, Journal of European Public Policy, 24/2.
  • Epstein, R., and Sedelmeier, U. (eds.) (2009) International Influence beyond Conditionality: Postcommunist Europe after EU Enlargement (London: Routledge).
  • Gateva, E. (2015) European Union Enlargement Conditionality (London: Palgrave).
  • Preston, C. (1997) Enlargement and Integration in the European Union (London: Routledge).
  • Schimmelfennig, F., and Sedelmeier, U. (2005a) The Europeanization of Central and Eastern Europe (Ithaca, NY: Cornell University Press).
  • Schimmelfennig, F., and Sedelmeier, U. (eds.) (2005b) The Politics of European Union Enlargement: Theoretical Approaches (London: Routledge).
  • Schimmelfennig, F. and Sedelmeier, U. (2020) ‘The Europeanization of Eastern Europe: The external incentives model revisited’, Journal of European Public Policy, 27/6: 814–33.
  • Schumacher, T., Marchetti, A., and Demmelhuber, T. (eds.) (2018) The Routledge Handbook on the European Neighbourhood Policy (London: Routledge).
  • Sedelmeier, U. (2005) Constructing the Path to Eastern Enlargement: The Uneven Policy Impact of EU Identity (Manchester: Manchester University Press).
  • Vachudova, M. (2005) Europe Undivided: Democracy, Leverage, and Integration after Communism (Oxford: Oxford University Press).
  • Web Links

    Commission information and documents on enlargement and Neighbourhood Policy

    MAXCAP (Maximizing the Integration Capacity of the EU) was a 2013–16 project on enlargement and integration capacity that published numerous papers and briefings.

    EU-STRAT was an international research project (2016–19) on the EU’s relationship with states in the European Eastern neighbourhood that published many interesting papers and briefings.

    Explore this topic further with additional web links to reliable content on EU politics.


    • 1 UN World Urbanization Prospects 2018, data for 2020; Kosovo included in Serbia.

    • 2 World Bank, World Development Indicators database.

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