Variable geometry may not only refer to ways to alter the shape of an aircraft's wings in flight in order to alter their aerodynamic properties but also to a concept for multi-speed Europe, a proposed strategy for European integration, next the forms of multi-speed Europe and Europe a la carte.

'Variable-geometry' Europe is the term used to describe the idea of a method of differentiated integration which acknowledges that there are irreconcilable differences within the integration structure and therefore allows for a permanent separation between a group of Member States and a number of less developed integration units. DI is considered to be a tool to achieve common aims and policies in politics, social fields, economy, legislation and institutional issues to strengthen sovereignty or to enhance effective capacity.

Multi-speed Europe, called also variable geometry Europe or Core Europe depending on the form it would take in practice, is the idea that different parts of the European Union should integrate at different levels and pace depending on the political situation in each individual country. Indeed, multi-speed Europe is currently a reality, with only a subset of EU countries members of the eurozone and of the Schengen area. Like other forms of differentiated integration such as à la carte and variable geometry, multi-speed Europe arguably aims to provide a solution to the dilemma between unity and diversity, widening and deepening of the European Union.

The concept entered political discourse when, after the end of the Cold War, an eastward enlargement of the European Union began to materialize and the question arose how "widening" could be made compatible with "deepening", i.e., how the imminent enlargement process could be prevented from diluting the idea of an "ever closer union among the peoples of Europe", as the Treaty establishing the European Economic Community of 1957 had put it.

In 1994 – still at a time of the EU12 – the German Christian Democrats Wolfgang Schäuble and Karl Lamers published a document in which they called for a Kerneuropa (= core Europe). This idea envisaged that "core Europe" would hav a magnetic attraction for the rest of Europe. A precursor to that concept had been a proposal by two advisors to German Chancellor Helmut Kohl, Michael Mertes and Norbert J. Prill, published as early as July 1989. Mertes and Prill called for a concentric circles Europe, built around a federal core consisting of the EU6 and like-minded EU member states. In 1994 they partly revoked their original idea, arguing that the post-Cold War EU would rather look like a “Europe of Olympic rings” than a "Europe of concentric circles".


Institute for Comparative Federalism on differentiated integration in 2018 | The external dimension of a multi-speed, multi-tier EU | two or more speeds | three pillars are important for creation of DI | multi-speed Europe concept | the variances of Europe | Two tier Europe - really? | Gravitational power’ meets its ‘normative power | Many Concepts, Sparse Theory, Few Data (ETH Zurich)


  Institute for Comparative Federalism on differentiated integration in 2018
"Differentiated integration in 2018" (elaboration by our director Francesco Palermo, Institute for Comparative Federalism, based on an earlier graph
by Institute Jacques Delors, 2013)


  two or more speeds
The external dimension of a multi-speed, multi-tier EU  
6 May 2013, CEPS, university of Copenhagen, EPIN, ACELG and CLEER organized an event about the external dimension of a multi-speed, multi-tier European Union to map out the various ways and means by which differentation is given form and future constitutional, institutional and instrumental challenges. During the event it was emphazised that the steps towards a deeper economic and monetary union (EMU) have not and will not split up the Union; a statement that triggered some controversy. One of the lessons drawn from the discussion was the need to reinforce the principle of legal homogenity, possibly by expanding the jurisdiction of the Court of Justice of the EU in the real of EU external action.

Accommodating differentiation in EU Law and Policy is no new phenomenon but a concept which has been integral to European integration from the Treaty of Rome. It is to be generally understood as a ‘model of integration strategies that try to reconcile heterogeneity within the European Union and allow different groupings of Member States to pursue an array of public policies with different procedural and institutional arrangements’ (A. Stubb, 1996). While considered a convenience to accommodate different socio-economic and political interests of Member States in a European Union of 27/28 members, it is increasingly provoking questions on where its legal and constitutional boundaries lie in an organisation based on a special legal nature with common institutions and common principles.

The issue of European integration in two or more speeds is back. While previously this was the subject of academic circles, it has now moved into policy circles. Is this the future of Europe? Would the idea of proceeding in two or more speeds provoke a break-up of the EU? Is it an opportunity for each country to rethink and renew its commitments to the European project?
Bruegel Annual Meetings 2017, European Parliament, government of Italy and Estonia, EBDR, Avenir Suisse.
Three pillars are important for creation of DI  
The sovereign debt crisis has led to a thorough re-assessment of European Integration as a project. For some Member States the fiscal, economic and political union based on federal principles is right around the corner; for others as the UK, renegotiated their relationship to European Union.

In EU foreign policy there already exist various kinds of differentiation, both of a structural and of an ad hoc nature. On the structural side, examples include the former second pillar, opt-outs of CSDP, the external dimension of AFSJ (visa facilitation agreements, readmission), and the external dimension of the Euro and impact on external representation in international financial institutions and regulatory bodies.

On the ad hoc side, there is constructive abstention in CSDP, the notion ‘interested member states’ in external migration policy, and so on. As a consequence of the specificity of EU external relations, this area is often approached from the perspective of “coherence”: delivering a single message, or even speaking with a single voice, in spite of all the underlying differences.

Three pillars are important for creation of DI: constitutional, institutional and instrumental.

At constitutional level, it should be clear:

- how differentiated ratification of the foundational treaties does impact EU external relations and if it affect its constitutional foreign policy objectives in any way
- or constructive abstention and enhanced cooperation could be taken further so as to create ad hoc or structural “avant garde” groupings in “EU” external relations and if opt-outs (*) and opt-ins (*) can be.reconciled with the ‘common’ character EU external action
how internal variable geometry does impact general principles of EU law such as coherence, the exclusive and shared nature of competences, increased complementarity of competences, the.principle of conferral, legal homogeneity or the duty of sincere cooperation
or more cooperation will begin to take place outside the EU’s legal framework: “Member States in Council”, or more far-reaching: Schengen-type (inter se) agreements on EU external action-related issues

For institutional level applies:

- or a new institutional balance will be required to accommodate internal diversity to support EU external policies? Is treaty change required or would new inter-institutional agreements and settlements emerge? What will they look like?
- which procedural arrangements will have to be made in order to safeguard respect for the general principles of EU law (e.g. legal homogeneity within and beyond the EU legal order)
- or new budgetary mechanisms will be necessary to accommodate internal diversity?
- or various forms of representation in bilateral and multilateral settings will see the light of day (e.g. “the EU and certain (10, 17, 27, 28) Member States”)?

And on the instrumental level:

- or we will we see new forms of mixity/hybridity, depending on the policy area at issue and what they will look like and what legal consequences they will have
- or the use of (internal or external) soft law arrangements wuill become even more widespread in EU external relations, and how this would impact its effectiveness.


multi-speed Europe concept  
During the event, ATALANTA, forces of operation as result of the continuing impact of piracy and armed robbery at sea off the coast of Somalia on international maritime security and on the economic activities and security of countries in the region, was brought to the table as a good example within the strategy of DI. Based on the principle of non-exclusion, legitimacy, solidarity and with respect to identities it can serve as model for polity in a changing multipolar world. But in respect of further convergence in European integration, there are more areas that qualify. Acquis, democracy (through the European Parliament) due to transparancy for citizens, consistency, sovereignty, ways of decision making (intergovernmental, supranational, Council of the EU), design of and representation in IO's.

The multi-speed Europe concept has been debated for years in European political circles, as a way to solve some institutional issues. The concept is that the more members there are in the Union, the more difficult it becomes to reach consensus on various topics, and the less likely it is that all would advance at the same pace in various fields. Following deeper differences, a research paper on the issue called 'Strengthening the Core or Splitting Europe?', was drafted in March 2013 by Stiftung Wissenschaft und Politik. The paper accurately describes prospects and pitfalls of a strategy of differentiated integration such as the legal foundations, shifting political balance in the Union, exclusion, new eurozone's governance structure.

The euro crisis brought with it political consequences and changed the shape of the EU. Multi-tier Europe is a reality, participants agreed at the November 2012 Allianz-CER Forum. Only 17 of 27 EU member-states share a single currency and, “we cannot expect all EU countries to join the euro, so this division is permanent”. The UK and Ireland do not participate in the Schengen area of borderless travel. Smaller groups of European countries have got together in the past to run military missions. EU countries have started using the treaty clause on ‘enhanced co-operation’ to implement policies that not all member-states want to take part in. One enhanced co-operation on divorce law is in force; two others – on a financial transaction tax and on an EU patent – are in the works. “We had better get used to this, this is our future.”


  the variances of Europe
Intermediate forms could be limited to some areas of close cooperation, as some historical examples are given below. It is also possible now for a minimum of eight EU member states to use enhanced co-operation, but this new framework has been used only once. A second proposal, a unified European patent, is nearing completion [as of December 2010] with only two countries (Italy and Spain) not participating. This idea has been revived recently because of various events, such as:
  • the Euro with 17 EU member-states and three more in ERM II on track to joining. All but two states (Denmark, United Kingdom) have agreed by treaty to join but at least one of those treaty signatories (Sweden) has made no further steps to do so.

  • the Schengen area Treaty leading to a common border for many EU states (it currently excludes Bulgaria, Cyprus, Ireland, Romania and the United Kingdom) but which includes four non-EU members - Norway, Switzerland, Iceland and Liechtenstein. It is often asserted that Ireland only reluctantly agreed to stay out of the treaty to avoid creating a physical border between the Republic and Northern Ireland because the UK had refused to sign.

  • other initiatives limited to some states, such as the European Defence Initiative and Prüm Convention.

  • the enlargement of the European Union to 27 member-states, with the prospect of accepting Croatia in 2013 and in the forthcoming years other candidates (Turkey, Montenegro, Macedonia, Serbia and Iceland among others) where new members initially don't join the Schengen area and the Eurozone for some time.

  • the European Convention that led to the European Constitution that was signed in 2004 by the 25 Heads of State, but was not ratified by all national parliaments or assemblies and so failed. Later most of its provisions were adopted trough the Treaty of Lisbon that included additional opt-outs for some states.

  • differences of view between EU members on some foreign diplomatic and military issues.

The Economist in a 2004 article compared the variances of Europe to a lake that has many deep parts (areas in which countries are similar) and many shallow parts (areas in which countries have major differences). Currently in the EU
there are the following cases of non-uniform application of the European Union law:

permanent deviations
request by states to cooperate more than EU
(post-accession: request to participate at EU level instead of request by states
to cooperate less than general EU level less)
allowed by the EU

Enhanced co-operation

Opt-outs in the European Union
Minor EU law derogations or exemptions special territories status

not allowed by the EU

Mechanism for Cooperation and Verification Eurozone/Schengen suspensions
(post accession: benchmarks for adoption of EU level

potentially any Legislation adopted per QMV instead of unanimous voting

A number of countries have special relations to the European Union implementing most of its regulations. Prominently there are Norway, Iceland, Switzerland and Liechtenstein which are the only remaining EFTA members while all other former EFTA members have converted into EU members. Through agreements Norway, Iceland and Liechtenstein (not including Switzerland) are members of the European Economic Area since 1994. As a consequence of taking part in the EU single market they need to adopt part of the Law of the European Union. Formally they would not need to fund the EU government but in practice they have opted to take on their part of financing EU institutions as required by EU law (see EEA and Norway Grants) with the financial footprint of Norway being equal to that of an EU member since 2009. Especially Norway and Iceland are known to forfeit EU membership on the basis of EU fishery regulations that they want to opt-out on. Both Norway and Iceland have signed and implemented the Schengen zone agreements. During the turmoils of the financial crisis Iceland was looking into membership of the Eurozone and it did formally apply to EU membership in 2009. Norway has joined all EU political treaties and it has applied to EU membership multiple times but while fulfilling the requirements the government was vetoed by public vote in their own country in 1972 and 1994. This leaves Norway to be integrated into Inner Europe's institutions while not being part their governing body.


Two tier Europe - really?  
This article was first published in the CEPS publication "Differentiated Integration in the EU – From the inside looking out" and is republished with the kind permission of the author Dr Richard Corbett, Member of the European Parliament 1996-2009, Advisor to the President of the European Council 2010-14, MEP candidate in the May 2014 elections.

People have been discussing a multi-tier Europe for decades: after all, the ECSC project in 1950 created what was then seen as a two-speed Europe, involving just 6 of the then 14 Member States of the brand new Council of Europe. But within our current European Union, I would argue that the several instances of variable integration fall short of creating a two tier Europe. We do not have an avant garde group, but we have several different arrières gardes:

CEPS book January 2014 analyses the various means by which differentiation is shaped in the realm of EU external action
  • Ten Member States not (or not yet) in the euro
  • Ireland, UK, Cyprus, (and Romania and Bulgaria not yet) in Schengen;
  • Denmark not in defence cooperation;
  • UK, Ireland and Denmark not participating in all AFSJ areas.
  • Denmark with an exemption from the single market as regards secondary residencies.
  • Spain and Italy not joining the unified EU patent;
  • Twelve states not in divorce law cooperation.
  • UK and Poland protocol interpreting the Charter of Right’s effect on their domestic law.
  • UK and Czech Republic not in Stability Treaty (fiscal compact).

What is striking is that these arrières gardes always consist of a small number of states, often just one or two, always a different configuration (even if some countries appear frequently), and often seen as an anomaly, exception or temporary situation. For all areas where EU acts, either all (usually), or the overwhelming majority of MS participate. Other than on Eurozone matters, of which more below, there is also no institutional separation, no two-tier structures or separate institutions apart from, in the Council, differentiated voting, but with everyone around table. In the Commission, Parliament and Court, there is no differentiated voting.

Other than on Eurozone matters, of which more below, there is also no institutional separation, no two-tier structures or separate institutions apart from, in the Council, differentiated voting, but with everyone around table. In the Commission, Parliament and Court, there is no differentiated voting.

The sole exception to this is on Eurozone matters, where there are separate (under the treaty, "informal") meetings of the Eurogroup of finance ministers and Eurozone Summits at the level of heads of state or government (but even those have the same President as the European Council, and its meetings are normally held in conjunction with European Council meetings). And on Eurozone matters too, Commission, Parliament and Court remain whole, with no differentiated voting. But what about further deepening of the Eurozone? Clearly those sharing a common currency are having to do more together to manage their common currency. Does this potentially lead to two-tier Europe? It evidently does to a degree, and this has already happened in large part. But I see seven reasons why it will not lead to fully fledged two-speed Europe.

  • First, the group is clearly not an avant garde on any other subject than those directly linked to the common currency (not foreign policy, justice, environment, transport, agriculture, fishing, consumer protection, competition policy, etc.)

  • Second it is not a fixed membership group, others will join, only two have legal opt-outs (and even they have a right to reconsider). It is not a fixed-boundary division.
  • Third, the deepening measures which have been taken as response to economic crisis, have, in many cases, been at the level of the whole Union, and only some at level of the euro. For example, the three European Supervisory authorities for the financial sector (European Banking Authority, etc), the European Systemic Risk Board, substantial legislation on the financial sector, the reinforced excessive deficit procedure, the EU Semester as a means of intensifying macroeconomic policy co-ordination, have all been done at the level of the whole Union.
  • Fourth, what HAS been done at eurozone level, has usually been done in a way that was deliberately open to others to participate, and attempts have been made to expressly minimize the institutional split between the 17 and the rest. For example: the Stability Treaty ("Fiscal compact"), was done at level of eurozone, but almost all the others wanted to join and in the end only two did not sign it. Furthermore its architecture was designed to keep it as close as possible to the EU system. Another example, currently underway, the banking union: although one could argue that this is needed for the single financial market as much as for the single currency, it was done at level of eurozone + others that wanted to join -- but every care was made to ensure single market compatibility, including a "double majority" voting procedure to safeguard the "outs". Further example: the Eurozone Summits: these are being held in conjunction with European Council meetings, not stand-alone. Everyone can raise an issue before the 17 meet separately. It has been given the same President to ensure institutional coherence. Also, at least one of the two annual meetings is open to all signatories of the Stability treaty, not just the Eurozone.
  • Fifth , the bulk of what the EU does, even economically, is at the level of the whole EU of 28. The single market is crucial in this respect, it is the glue that holds EU together and generates bulk of EU legislation. The common rules on consumer protection, competition, state aids, standards, etc, etc, is at level of whole EU. So is trade policy, environment, R&D programmes, and of course all the non-economic matters such as foreign policy, police & justice, etc.
  • Sixth, no separate institutional structures have been set up, other than the ESM. The ESM is indeed intergovernmental at eurozone MS level. After all, it is financed by national money or guarantees (the EU budget is far too small) and the Member States are the shareholders, so they sit on the board of governors. In practice, however, when it comes to using this instrument, they rely on the Commission for country specific reports, to negotiate MoUs, etc.
  • Last, in the case of the Stability Treaty, its architecture has been designed to avoid divergence. (It was not even originally intended to have a separate treaty -- that resulted from UK non-cooperation in December 2011.) Every care has been taken to hug the EU institutions closely: role of Commission, use of ECJ, etc. And not just Eurozone Member States, but all bar two Union Member States joined in, so rather than being a separate construction, the correct analogy is that of my colleague Luuk Van Middelaar, that it is a buttress, supporting the main structure, not a separate building.

There are, of course, different narratives about all of this, not just in academia, but also among Member States. Nonetheless, the compromises reached do limit the two-tier divergence.

So far, so good. But what of the future? Is there possible treaty change coming? In general we find that much can be done within existing treaties, more than perhaps initially considered possible. And many of the things for which treaty change would be necessary are things for which there is anyway no consensus (like fully fledged Eurobonds). The procedure for treaty change is long and difficult. And now, the situation in the UK doesn't encourage others to go down the route of treaty change. What, indeed, about Cameron's January 2013 speech? That speech was more as party leader, rather than as government leader, and about what a future UK government would do, if the Conservatives win absolute majority in 2015. Up to now no other major party has matched that pledge. There is therefore no certainty yet that further opt-outs or renegotiation or devolution will be on the table in the way that Cameron seemed to envisage. If this eventuality does arise, it remains to be seen what emphasis will be given to multilateral reforms or to unilateral opt-outs, what other Member Sates are willing to accept, and whether the focus will be primarily on treaty change or changes to legislation.

To conclude, expectations of an emerging two-tier system must be nuanced by a host of factors that limit the division into two tiers, blur the boundaries and maintain the primary importance of the whole Union.

opt-in..: to decide that you want to do something or be involved in something;
opt-out: to decide not to take part in something or to stop taking part in it.


  Many Concepts, Sparse Theory, Few Data
Gravitational power’ meets its ‘normative power
variable geometries of power
Gravitational power’ meets its ‘normative power’. In November 2006 CEPS, the Centre for European Policy Studies, spent in a study on controversies and ambiguities characterising the EU neighbourhood strategy attention to the meanings and possible usages of the term 'variable geometry', a branch of mathematics. In this study, three dimensions of variable geometries are distinguished:
  1. the first dimension relates to ideas and focuses on the way in which the EU as a polity affects, and is affected by, deeper relations with its neighbours.
  2. the focus is on institutions and illustrates the rationale behind and options for deeper institutional integration of neighbours into the EU;
  3. lastly, the study ventures into an analysis of the wider Europe as a power constellation and thus explains what variable geometry means in relation ....to security and stability in the European neighbourhood.
ETH, one of the leading international universities for technology and the natural sciences, gives also close attention to the feature of differentiated integration and compiled the study 'Differentiated Integration in the European Union, Many Concepts, Sparse Theory, Few Data':

Differentiated integration has been the subject of political discussion and academic thought for a long time. It has also become an important feature of European integration since the 1990s. By contrast, it is astonishing how poor our research and knowledge about the phenomenon is. Whereas there is an abundance of conceptual work and some normative analysis, positive theories on the causes or effects of differentiated integration are rare. Empirical analysis has concentrated on a few important cases of treaty law (such as EMU and Schengen) while there is no systematic knowledge about differentiated integration in secondary law. The aim of this article is therefore twofold:

- to review the existing typological and theory-oriented research and
- to outline a research agenda striving for systematic empirical and explanatory knowledge

ETH Zurich, European Politics Research Group: Differentiated Integration in the European Union