The European Union

By the end of this lesson, students will be able to:

• Account for how the formation and existence of the European Union shaped economic developments from the Second World War to the present (Skill 3.B; LO J).
• Account for how the European Union shaped national and European identity from the Second World War to the present (LO K).
• Account for KC-4.4.IV: how European states began to set aside nationalist rivalries in favor of economic and political integration, forming a series of transnational unions that grew in size and scope across the second half of the twentieth century.
• Account for KC-4.4.IV.A: how the ECSC developed into the EEC and the EU, producing increasing economic and political integration and efforts to establish a shared European identity.
• Account for KC-4.4.IV.B: how EU member nations continue to balance questions of national sovereignty with the responsibilities of membership.
• Identify the evidence that founding-treaty and contemporary EU sources supply for arguments about the integration project (Skill 3.B in direct practice).

Topic 9.10 is the dual-theme topic in Unit 9. The economic-developments dimension (LO J, ECD theme) and the national-and-European-identity dimension (LO K, NEI theme) examine the same historical phenomenon — the long European integration project — through two different thematic lenses. KC-4.4.IV captures the framework: European states began to set aside nationalist rivalries in favor of economic and political integration, forming a series of transnational unions that grew in size and scope. KC-4.4.IV.A traces the institutional evolution from the ECSC through the EEC to the EU. KC-4.4.IV.B identifies the sustained tension between national sovereignty and EU membership. The lesson is structured in four parts: the founding period (1950-1957); the deepening period (1957-1992); the eastern enlargement and crises (1992-2016); and the post-Brexit era (2016-present).

The founding period (1950-1957). Topic 8.11 covered the Schuman Declaration of 9 May 1950 and the broader postwar institutional reconstitution; Topic 9.2 covered the European Coal and Steel Community of 1952 as part of the postwar reconstruction. The principal early-1950s integration debate produced two parallel projects: the ECSC institutional framework (operational from 23 July 1952) and the proposed European Defence Community (the Pleven Plan of October 1950 that would have produced a unified European army; the EDC Treaty of 27 May 1952; the EDC failure in the French National Assembly on 30 August 1954 over French and Gaullist sovereignty concerns). The EDC failure substantially redirected the integration project from defense and political integration toward economic integration.

The Treaties of Rome of 25 March 1957 (in force 1 January 1958) established the European Economic Community (EEC) and the European Atomic Energy Community (Euratom). The six founding members (Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany) committed to the establishment of a customs union (eliminating internal tariffs and producing a common external tariff), a common agricultural policy (CAP, operational from 1962, with substantial price-support and supply-management arrangements), the free movement of workers and capital, and the broader four freedoms (goods, services, persons, capital). The EEC's principal institutions reproduced the ECSC institutional framework: the European Commission (proposing legislation; under Walter Hallstein's first presidency 1958-1967); the Council of Ministers (the principal decision-making body, with weighted voting on most matters); the European Parliamentary Assembly (renamed the European Parliament in 1962, initially with delegated members from the national parliaments); and the European Court of Justice (developing the principal legal doctrines including direct effect in the 1963 Van Gend en Loos judgment and supremacy of EC law in the 1964 Costa v. ENEL judgment).

The deepening period (1957-1992). The 1960s and 1970s produced substantial deepening of the EEC institutional framework alongside notable enlargements. The Empty Chair Crisis of June 1965 to January 1966 (the French boycott of EEC institutions under Charles de Gaulle, principally over the Hallstein Commission's proposed expansion of qualified-majority voting; resolved by the Luxembourg Compromise that effectively preserved national veto on matters of "very important interest") substantially constrained the supranationalist development of the EEC through the 1970s. The Merger Treaty of 8 April 1965 (in force 1 July 1967) consolidated the ECSC, EEC, and Euratom institutions into a single set of institutions known as the European Communities. The first enlargement of 1 January 1973 admitted Denmark, Ireland, and the United Kingdom; de Gaulle had vetoed the British application twice (in 1963 and 1967); the post-de-Gaulle Pompidou government accepted the British accession; the British 1975 referendum on continuing EEC membership produced a 67 percent yes vote.

The 1981 enlargement admitted Greece (after the 1974 end of the Greek military junta and the 1975 democratic constitution); the 1986 enlargement admitted Spain and Portugal (after their post-1974 transitions to democracy). The Single European Act of 17 February 1986 (in force 1 July 1987) substantially extended qualified-majority voting, formalized European Political Cooperation, and committed the member states to completing the single market by 31 December 1992 (the "1992 programme" of approximately 280 directives). The Schengen Agreement of 14 June 1985 (signed initially by France, West Germany, Belgium, Luxembourg, and the Netherlands; the Schengen Convention of 19 June 1990; operational from 26 March 1995 across the original signatories plus subsequent accessions) abolished internal border controls within the participating states. The Maastricht Treaty (Treaty on European Union) of 7 February 1992 (in force 1 November 1993) established the European Union as a three-pillar structure: the European Communities pillar (incorporating the ECSC, EEC renamed European Community, and Euratom); the Common Foreign and Security Policy pillar; and the Justice and Home Affairs pillar. The treaty also created EU citizenship, the convergence criteria for the eventual euro, and the broader institutional framework that subsequent treaties would extend.

Eastern enlargement and crises (1992-2016). The post-Maastricht period produced substantial institutional development alongside the principal post-Cold-War challenges. The euro was the principal Maastricht-derived institutional development. The Maastricht convergence criteria (inflation; long-term interest rates; government deficit below 3 percent of GDP; government debt below 60 percent of GDP; exchange-rate stability within the European Exchange Rate Mechanism) governed the qualifying-state determination; the European Monetary Institute (operational 1994-1998) provided the institutional foundation; the European Central Bank (operational from 1 June 1998 in Frankfurt) replaced the European Monetary Institute and assumed responsibility for the euro. The euro launched in electronic form on 1 January 1999 across eleven initial member states (Austria, Belgium, Finland, France, Germany, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain; Greece joined on 1 January 2001 after meeting the convergence criteria; Slovenia, Cyprus, Malta, Slovakia, Estonia, Latvia, and Lithuania subsequently joined; Croatia became the 20th eurozone member on 1 January 2023). Physical euro banknotes and coins entered circulation on 1 January 2002.

The eastern enlargement of 1 May 2004 was the principal post-1989 EU achievement and the largest single enlargement in EU history. Ten new member states acceded simultaneously: Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia. The accessions extended the EU substantially into former Eastern bloc territory; the new members substantially aligned EU institutional, legal, and economic life with the long-running European institutional framework. Bulgaria and Romania acceded on 1 January 2007; Croatia on 1 July 2013. The proposed European Constitutional Treaty of 29 October 2004 was rejected in the French and Dutch referendums of May-June 2005 over substantial popular concerns about the integration project's pace and democratic legitimacy; the substantively comparable Treaty of Lisbon (signed 13 December 2007; in force 1 December 2009 after the second Irish referendum approved it) provided the principal subsequent institutional reform. The Lisbon Treaty incorporated the Charter of Fundamental Rights of the European Union (initially proclaimed 7 December 2000, made legally binding 1 December 2009); created the position of President of the European Council (Herman Van Rompuy was the first, 2009-2014; subsequent presidents Donald Tusk 2014-2019, Charles Michel 2019-2024, Antonio Costa from 2024); and the position of High Representative for Foreign Affairs and Security Policy.

The 2010-2012 Eurozone crisis (Topic 9.6 covered) substantially tested the EU institutional framework. The Greek government-debt crisis from October 2009; the Irish, Portuguese, Spanish, Italian, and Cypriot follow-on crises; the European Central Bank's Outright Monetary Transactions program from August 2012; and the European Stability Mechanism (operational from October 2012) provided the principal crisis-management framework. The 2015 European migration crisis substantially tested the Schengen framework; the European Union's response (the EU-Turkey statement of March 2016; the Common European Asylum System reforms of 2016-2024) addressed the immediate crisis but produced sustained political contestation across the member states (Topic 9.11 will examine in detail).

The post-Brexit era (2016-present, KC-4.4.IV.B). The British referendum of 23 June 2016 (51.9 percent leave, 48.1 percent remain; turnout 72.2 percent) substantially demonstrated the KC-4.4.IV.B sovereignty-membership tension. The Theresa May Conservative government invoked Article 50 of the Treaty on European Union on 29 March 2017, formally beginning the two-year withdrawal-negotiation period. Substantial subsequent negotiations under May (the November 2018 Withdrawal Agreement that the British Parliament rejected three times in early 2019) and Boris Johnson (the revised October 2019 Withdrawal Agreement; the December 2019 general election that produced a Conservative parliamentary majority) produced eventual ratification. The United Kingdom formally departed the EU at 11:00 p.m. GMT on 31 January 2020; the transition period (during which the UK remained within most EU structures pending the trade-relationship negotiation) ended on 31 December 2020; the EU-UK Trade and Cooperation Agreement of 30 December 2020 (in force provisionally from 1 January 2021; formal entry into force 1 May 2021) established the post-Brexit relationship.

The post-Brexit EU has continued to develop. The Russian invasion of Ukraine on 24 February 2022 substantially reorganized EU foreign-policy and energy-policy positions: the EU adopted substantial sanctions packages against Russia; the EU committed to substantial Ukrainian support including military aid through the European Peace Facility; Ukraine, Moldova, and Georgia received candidate status (Ukraine and Moldova on 23 June 2022; Georgia on 14 December 2023, suspended in mid-2024 over the ruling Georgian Dream party's authoritarian turn); Bosnia and Herzegovina received candidate status on 15 December 2022. The post-2024 European political environment has produced sustained populist-nationalist pressure (the 2024 European Parliament elections produced substantial gains for nationalist parties; the 2024-2025 French and German political crises) that the long-running KC-4.4.IV.B sovereignty-membership tension continues to shape.

The Skill 3.B argument. Topic 9.10's suggested skill is 3.B (Source Evidence: identify the evidence used in a source to support an argument). The skill applies particularly to the substantial documentary record of the European integration project: the founding treaties (the Treaties of Paris 1951, Rome 1957, the Single European Act 1986, Maastricht 1992, Nice 2001, Lisbon 2007); the principal European Court of Justice judgments (Van Gend en Loos 1963; Costa v. ENEL 1964; subsequent supremacy and direct-effect jurisprudence); the principal political documents (Schuman Declaration 1950; the Single Market 1992 White Paper; the Constitutional Treaty 2004); and the contemporary documents of the British withdrawal (the Cameron February 2016 renegotiation outcome; the May March 2017 Article 50 letter; the Johnson October 2019 Withdrawal Agreement). Each source's claims are supported by specific evidence (particular treaty provisions; particular factual situations; particular legal-institutional precedents); students should identify the specific evidence each source uses to support its substantive argument about the integration project's economic and identity dimensions.

Three sources framing the integration project: the founding economic treaty, the political-union treaty, and the principal sovereignty-membership crisis document.

1. (Continuity and Change, Skill 3.B) Identify the specific evidence the Treaty of Rome (1957) uses to support its claim of an "ever closer union among the peoples of Europe." What specific provisions and institutional commitments anchor the founding economic-integration claim?
2. (Continuity and Change) Account for how the integration project produced both economic developments (LO J) and reshaped national and European identity (LO K) across the period from 1957 to the present. How are the two dimensions related, and how are they distinct?
3. (Continuity and Change, Skill 3.B) Identify the specific evidence the Maastricht Treaty (1992) uses to deepen the integration project beyond the EEC's principally economic foundation. What does EU citizenship, the convergence criteria for the euro, and the three-pillar structure each contribute?
4. (Continuity and Change) Account for KC-4.4.IV.B: how have EU member nations balanced questions of national sovereignty with the responsibilities of membership? Cite the Empty Chair Crisis of 1965-1966, the Maastricht ratification difficulties, the 2005 Constitutional Treaty rejection, and the British 2016-2020 withdrawal.
5. (Continuity and Change, Skill 3.B) Examine the evidence that the May Article 50 letter (March 2017) supplies for the British post-referendum diplomatic position. What specific claims does the letter advance, and what evidence does it use to support them?

Draft alignment — pending educator review. AP European History codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, V.1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.