The Founding Communities: The ECSC, EEC, and Euratom
Last updated on November 1, 2026
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The Founding Communities: The ECSC, EEC, and Euratom
Introduction
The European Union did not emerge as a single organisation established through one founding treaty. Its institutional and legal foundations developed through three distinct European Communities: the European Coal and Steel Community (ECSC), the European Economic Community (EEC) and the European Atomic Energy Community (Euratom).
These Communities were established through separate international treaties, each addressing a particular dimension of European cooperation. The ECSC concentrated on coal and steel production, the EEC sought to establish a common market covering the wider European economy, and Euratom promoted cooperation in the peaceful development and use of nuclear energy.
Although their objectives differed, the three Communities shared an important characteristic: they introduced a new form of institutional cooperation in which participating states agreed to exercise certain powers through common European institutions.
This arrangement represented a significant departure from traditional international organisations. Rather than relying exclusively on diplomatic coordination and decisions adopted by national governments, the Communities developed independent institutions, binding legal instruments and judicial mechanisms capable of ensuring compliance with common rules.
Their development also produced a distinctive legal system. Community legislation increasingly affected individuals, businesses and national authorities, while the Court of Justice established fundamental principles governing the relationship between European law and domestic legal systems.
The three Communities therefore formed the institutional laboratory in which the modern European legal order was created.
Understanding their separate legal identities, founding treaties, institutional arrangements and historical development is essential to understanding the constitutional structure of the European Union today. It also explains why certain European legal arrangements, particularly Euratom, continue to operate under a separate treaty framework despite their close institutional relationship with the Union.
1. The Historical and Legal Context of the Founding Communities
The establishment of the European Communities must be understood within the political circumstances of post-war Europe.
Following the Second World War, the governments of Western European countries faced the simultaneous challenges of economic reconstruction, political stabilisation and long-term security.
The traditional European system had been based on independent states exercising authority within their territories and managing their external relations through diplomacy, treaties and alliances.
However, the experience of two world wars demonstrated the limitations of this arrangement when national economic and political interests became incompatible.
European leaders increasingly recognised that lasting peace required a more structured form of cooperation.
The initial approach was deliberately practical. Instead of attempting to create a European federal state, the participating governments concentrated on economic sectors in which common management could produce immediate benefits and reduce the possibility of renewed conflict.
Coal and steel were particularly suitable for this purpose. They were essential to industrial development, transport, energy production and military manufacturing.
The first Community was therefore designed around a limited but strategically important economic objective.
Its success subsequently encouraged governments to extend integration into the wider economy and other areas of technological development.
Three Communities emerged from this process:
- The European Coal and Steel Community, established by the Treaty of Paris in 1951.
- The European Economic Community, established by the Treaty of Rome in 1957.
- The European Atomic Energy Community, also established by a separate Treaty of Rome in 1957.
Although they developed within a common political project, these organisations did not possess identical legal structures, competences or institutional arrangements.
The distinction is particularly important because the three Communities were separate legal entities, even when they shared certain institutions and administrative arrangements.
Their legal development eventually contributed to the establishment of the European Union, but their original treaties were not simply three parts of one constitutional document.
2. The European Coal and Steel Community: The First Supranational Community
Visites guidées – Weltkulturerbe Völklinger Hütte
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The European Coal and Steel Community was the first of the three Communities and the starting point of institutionalised European integration.
Its creation followed the Schuman Declaration of 9 May 1950, which proposed placing French and German coal and steel production under a common authority.
The proposal was based on the recognition that these industries were essential not only to economic reconstruction but also to military capacity.
By placing their production and distribution within a common framework, the participating states sought to make unilateral economic and military rivalry more difficult.
2.1. The Treaty of Paris of 1951
On 18 April 1951, Belgium, France, the Federal Republic of Germany, Italy, Luxembourg and the Netherlands signed the Treaty establishing the European Coal and Steel Community.
The treaty entered into force on 23 July 1952.
The six countries became known as the founding Member States of European integration.
The Treaty of Paris established the ECSC for a period of fifty years.
This limited duration was unusual because international organisations were generally not established through treaties containing such a specific termination date.
The decision reflected the experimental nature of the project. The participating states were creating an entirely new institutional arrangement in a strategically important industrial sector.
The treaty established a common market for coal, iron ore, scrap iron and steel products, subject to the precise categories and rules contained in its provisions.
Its principal objectives included:
- Eliminating customs duties and quantitative restrictions affecting trade in covered products.
- Preventing discriminatory pricing and commercial practices.
- Establishing fair conditions of competition.
- Ensuring access to industrial resources.
- Encouraging the modernisation and expansion of production.
- Improving employment and living conditions in the relevant industries.
- Preventing the concentration of economic power from undermining the common market.
The ECSC was not simply a customs agreement. Its purpose was to establish a common economic framework administered by independent institutions.
2.2. The legal nature of the ECSC
The ECSC possessed legal personality and could exercise rights and assume obligations within the framework established by its treaty.
Its institutions were empowered to adopt decisions and other legal instruments with binding effects.
The most distinctive feature of the Community was the High Authority, whose members were required to act independently of national governments.
This arrangement represented an important development in international institutional law.
In conventional intergovernmental organisations, governments generally retain direct control over decision-making through representatives who act on behalf of their national administrations.
The ECSC introduced a different model. Certain powers were entrusted to an independent authority expected to act in the general interest of the Community.
The Member States remained sovereign countries, but they had agreed that decisions in the defined field of coal and steel would be taken within a common legal and institutional framework.
The arrangement established an early model of supranational governance.
2.3. The institutional structure of the ECSC
The Treaty of Paris established four principal institutions.
The High Authority
The High Authority was the principal executive body of the ECSC.
Its members were appointed for fixed terms and were required to act independently of national governments.
It possessed significant powers relating to the functioning of the common market, including the adoption of decisions, supervision of economic activity and enforcement of treaty obligations.
Its institutional independence was one of the most important innovations of the ECSC.
The High Authority became the principal historical predecessor of the European Commission.
The Special Council of Ministers
The Special Council of Ministers represented the governments of the participating countries.
Its role was to ensure that national governmental interests were considered within the Community’s decision-making framework.
Depending on the matter, the Council participated in decision-making through consultation, agreement or other procedures established by the treaty.
The Council therefore provided an intergovernmental element within an otherwise strongly supranational institutional arrangement.
The Common Assembly
The Common Assembly consisted of representatives appointed by the national parliaments of the participating states.
It performed supervisory and parliamentary functions.
Although its powers were initially limited, it could exercise political control over the High Authority and, under the treaty arrangements, adopt a motion of censure.
The Assembly became an important institutional predecessor of the European Parliament.
The Court of Justice
The Court of Justice was established to interpret and enforce the treaty and supervise the legality of institutional action.
It provided judicial control over the exercise of Community powers and helped establish the foundations of a common European legal system.
The existence of a judicial institution was essential because the Community’s operation depended on legal obligations rather than political cooperation alone.
2.4. The economic and constitutional significance of the ECSC
The ECSC achieved something that had previously been difficult to imagine in traditional European diplomacy.
It established a common market in strategic industrial products and placed significant regulatory powers in the hands of an independent European authority.
Its importance was therefore both economic and constitutional.
Economically, it reduced barriers to trade in essential industrial resources and encouraged cooperation between producers and governments.
Constitutionally, it demonstrated that states could confer specific powers on independent institutions whose decisions would have binding legal consequences.
This model would influence the institutional architecture of the EEC and, eventually, the modern European Union.
2.5. The expiration of the ECSC Treaty
The Treaty of Paris was concluded for fifty years and expired on 23 July 2002.
Its expiration did not terminate European integration or dismantle the wider Community system.
By that time, the European Community had developed a much broader legal and economic framework.
The European institutions adopted arrangements to ensure the continuation of relevant activities and the integration of the remaining ECSC assets and obligations into the wider European framework.
The financial arrangements following the expiration of the treaty were governed by a specific protocol concerning the financial consequences of the expiry of the ECSC Treaty and the related Research Fund for Coal and Steel.
This development marked the end of the first specifically sectoral Community, while preserving the broader European integration project.
The ECSC therefore occupies a unique historical position: it was the first experiment in supranational European governance, but it was never intended to become a permanent general economic organisation.
3. The European Economic Community: From Sectoral Cooperation to a Common Market
Audiovisual Service – Signature of the Treaties of Rome
Meeting of the Hallstein Commission (1964) – CVCE Website
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The establishment of the European Coal and Steel Community demonstrated that supranational cooperation could operate successfully within a defined economic sector. However, the limitations of a sector-specific organisation soon became apparent.
European economic reconstruction required cooperation extending beyond coal and steel. Industrial development depended on transport, agriculture, energy, financial services, labour mobility and the removal of barriers affecting trade in a much wider range of products.
The six founding states therefore began considering the establishment of a general common market.
The negotiations culminated in the signing of the Treaties of Rome on 25 March 1957.
One of these treaties established the European Economic Community, which would become the principal foundation of the modern European internal market.
3.1. The Treaty establishing the European Economic Community
The Treaty establishing the European Economic Community entered into force on 1 January 1958.
Its six founding members were Belgium, France, the Federal Republic of Germany, Italy, Luxembourg and the Netherlands.
Unlike the ECSC, which concentrated on a limited number of industrial products, the EEC sought to establish a common market covering the wider economies of its participating states.
Its central objective was the progressive integration of national economies through the elimination of barriers to trade and the establishment of common policies.
The treaty envisaged a transitional period during which customs duties and quantitative restrictions between Member States would gradually disappear.
It also provided for the introduction of a common external tariff, creating a customs union between participating countries.
The EEC was therefore more ambitious than an ordinary free trade agreement.
A free trade area removes customs barriers between participating countries but allows each country to maintain its own external tariff arrangements. A customs union goes further by establishing a common external tariff towards third countries.
The EEC subsequently developed beyond the customs union towards a more comprehensive common market.
3.2. The principal objectives of the EEC
The original Treaty of Rome identified several objectives that shaped the development of the Community.
These included:
- Establishing a common market.
- Promoting harmonious economic development.
- Expanding economic activity.
- Improving living standards.
- Strengthening economic relations between Member States.
- Reducing economic disparities between regions.
- Developing common policies in selected economic sectors.
The treaty recognised that the elimination of customs duties alone would not be sufficient to create an integrated market.
Differences in national legislation, administrative requirements and economic regulation could continue to obstruct trade even after tariffs had disappeared.
Consequently, the EEC required common legislation and institutional mechanisms capable of ensuring that national governments respected their obligations.
This development made the Community increasingly important as a source of legislation affecting national legal systems.
3.3. The four fundamental freedoms
The EEC established the foundations for four freedoms that would become the defining features of the European internal market.
Free movement of goods
The treaty provided for the elimination of customs duties and quantitative restrictions between Member States and the establishment of a common external tariff.
The purpose was to allow goods to circulate within the Community without national customs barriers.
Free movement of persons
The treaty established the foundations for the movement of workers between Member States.
Workers would progressively acquire the right to seek employment in another participating country without being subjected to discriminatory treatment based on nationality, subject to the applicable treaty conditions and permitted exceptions.
Freedom to provide services and freedom of establishment
The treaty also provided for the removal of restrictions affecting cross-border economic activity.
Freedom of establishment concerned the ability of individuals and companies to pursue economic activities on a stable basis in another Member State.
Freedom to provide services concerned the temporary provision of economic services across national borders.
Free movement of capital
The treaty envisaged the gradual removal of restrictions on capital movements and payments between participating countries.
This freedom was developed progressively and eventually became one of the fundamental principles of the modern internal market.
These freedoms were not merely economic objectives. They required legal protection, judicial interpretation and the development of common regulatory standards.
They would eventually become important sources of rights for individuals and businesses.
3.4. The common agricultural and commercial policies
The EEC also established the foundations for common policies in areas where national economic decisions could significantly affect the functioning of the common market.
Agriculture was particularly important.
Agricultural production, food security, rural employment and price stability were major concerns in post-war Europe.
The original treaty therefore provided for a Common Agricultural Policy (CAP), which became one of the most substantial and financially significant areas of Community activity.
The EEC also established a common commercial policy, allowing participating states to pursue a more coordinated approach towards international trade.
These policies demonstrated that economic integration required a degree of common decision-making extending beyond the removal of trade barriers.
3.5. The institutional structure of the EEC
The EEC adopted an institutional structure influenced by the ECSC, although its institutional arrangements reflected the broader economic and political scope of the new Community.
Its principal institutions included:
The Commission
The Commission was responsible for promoting the general interests of the Community, supervising the application of the treaty and exercising important executive and legislative-initiative functions.
It played a central role in developing common policies and ensuring compliance with Community law.
The Council of Ministers
The Council represented the governments of the Member States and exercised important legislative and decision-making responsibilities.
It was initially the dominant legislative institution within the EEC.
The Parliamentary Assembly
The Parliamentary Assembly provided a representative and supervisory dimension to the Community.
Its members were initially appointed by national parliaments.
The Assembly subsequently developed into the European Parliament, with progressively expanding legislative and democratic powers.
The Court of Justice
The Court of Justice ensured the uniform interpretation and application of Community law.
It played a particularly important role in transforming the EEC from an economic cooperation arrangement into an autonomous legal system.
3.6. The EEC and the development of European legal integration
The EEC became the most influential of the three Communities in the development of European law.
Its broad economic competences generated an extensive body of legislation affecting businesses, individuals and national authorities.
The Court of Justice also developed fundamental doctrines concerning the legal effects of Community legislation.
In Van Gend en Loos (Case 26/62), the Court recognised that Community law could confer rights directly on individuals.
In Costa v ENEL (Case 6/64), it established the principle of the primacy of Community law over conflicting national law.
These judgments were particularly significant because they changed the legal relationship between the Community, its Member States and their citizens.
Community law was no longer understood solely as a collection of international obligations between governments. It became a legal system capable of operating within national judicial proceedings.
3.7. From the EEC to the European Community and the European Union
The legal identity and terminology of the EEC changed considerably over time.
The Maastricht Treaty introduced the broader European Union structure and renamed the European Economic Community as the European Community.
The change reflected the expansion of European integration beyond the original economic objectives.
The European Community continued to possess legal personality and exercised many of the Union’s supranational competences under the original Maastricht framework.
The Treaty of Lisbon subsequently abolished the formal pillar structure and replaced the European Community with the European Union as its legal successor.
The EEC therefore no longer exists as a separate organisation.
Its treaty framework, institutional achievements and accumulated body of law nevertheless form a central part of the modern European legal order.
The Treaty of Rome remains one of the most important historical foundations of European integration.
4. The European Atomic Energy Community: Euratom and the Legal Regulation of Nuclear Energy
Europäische Atomgemeinschaft Euratom – Der große Förderer der Kernenergie wird 60
Pull Down Map of Europe and the Atomic Activity (1961) – Etsy
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The third founding Community was established through the second Treaty of Rome, signed on 25 March 1957.
The European Atomic Energy Community, commonly known as Euratom, was created to promote cooperation in the development and peaceful use of nuclear energy.
Its establishment reflected the technological and economic expectations of the 1950s, when nuclear energy was increasingly regarded as a potentially transformative source of electricity and industrial development.
The participating states recognised that the development of nuclear technology required substantial investment, scientific expertise, access to nuclear materials, specialised infrastructure and effective safety arrangements.
Rather than allowing each country to pursue these objectives entirely independently, they established a common institutional and legal framework.
Unlike the ECSC and the EEC, Euratom was not designed to create a general market covering an entire economic sector. Its mandate was more specialised and focused on nuclear research, the supply of nuclear materials, safety and the development of nuclear energy for peaceful purposes.
4.1. The Treaty establishing Euratom
The Treaty establishing the European Atomic Energy Community was signed in Rome on 25 March 1957 and entered into force on 1 January 1958.
Its principal objective was to contribute to the formation and development of European nuclear industries and to ensure that all Member States could benefit from the development of atomic energy.
The treaty established a framework for:
- Promoting research into nuclear energy.
- Facilitating the exchange of scientific and technical information.
- Establishing common safety standards.
- Protecting workers and the general public against radiation hazards.
- Ensuring an equitable and regular supply of nuclear materials and fuels.
- Developing a common nuclear market within the treaty’s scope.
- Establishing safeguards against the diversion of nuclear materials from their intended peaceful uses.
- Encouraging investment and the development of nuclear infrastructure.
The treaty also established mechanisms for cooperation with third countries and international organisations.
Euratom was therefore conceived as both a research and industrial development framework and a regulatory system.
4.2. The political and economic motivations behind Euratom
The creation of Euratom was influenced by several considerations.
First, European governments were interested in reducing dependence on imported conventional energy resources.
Second, nuclear technology offered the possibility of developing substantial electricity-generating capacity and supporting industrial modernisation.
Third, nuclear research required extensive financial resources and scientific cooperation that could be difficult for individual states to provide independently.
Fourth, the peaceful development of nuclear technology required safeguards and common standards because the risks associated with radioactive materials could extend beyond national borders.
Euratom therefore combined economic development with scientific cooperation and public safety.
Its founding treaty also reflected the distinction between peaceful nuclear energy and military nuclear activities.
The Community’s activities were directed towards the peaceful uses of atomic energy. Its institutional and legal responsibilities did not create a general European military nuclear authority.
4.3. The institutional structure of Euratom
Euratom originally possessed an institutional structure closely connected to that of the EEC.
Its principal institutional arrangements included:
The Commission
The Commission was responsible for implementing the treaty’s objectives, promoting nuclear cooperation and exercising the regulatory and administrative powers conferred by Euratom law.
Its responsibilities included research coordination, nuclear safeguards and the development of common standards.
The Council
The Council represented the governments of the Member States and participated in the adoption of measures required for the implementation of the treaty.
The Assembly
The Parliamentary Assembly provided institutional supervision and political representation.
It later became part of the European Parliament’s institutional development.
The Court of Justice
The Court of Justice ensured the interpretation and application of Euratom law.
Its jurisdiction provided judicial control over the exercise of Community powers and contributed to legal consistency between the Communities.
The institutional arrangements were progressively consolidated through the Merger Treaty of 1965 and subsequent treaty reforms.
4.4. Euratom and nuclear safeguards
One of Euratom’s most important functions concerns nuclear safeguards.
The treaty established a system designed to ensure that nuclear materials are used in accordance with the purposes for which they are intended.
The Community developed inspection and monitoring mechanisms to verify that nuclear materials are not diverted from their declared peaceful uses.
These safeguards are distinct from, but connected to, the wider international system of nuclear non-proliferation.
The International Atomic Energy Agency (IAEA) is a separate international organisation that promotes the peaceful use of nuclear energy and operates international safeguards arrangements.
Euratom cooperates within this broader international framework while maintaining its own treaty-based responsibilities.
The distinction is legally important. Euratom is a European Community established under a treaty, whereas the IAEA is an international organisation with a global membership and a separate legal foundation.
4.5. Nuclear safety and radiation protection
Euratom has also become an important legal framework for nuclear safety and radiation protection.
The treaty provides the basis for the adoption of common standards concerning protection against ionising radiation and the safe use of nuclear materials.
European legislation developed under Euratom covers areas including:
- Basic radiation protection standards.
- Protection of workers and members of the public.
- Nuclear installation safety.
- Radioactive waste management.
- Emergency preparedness and response.
- Nuclear safeguards and verification.
- Cooperation concerning nuclear materials and fuel supply.
One particularly important legislative instrument is Council Directive 2013/59/Euratom, which establishes basic safety standards for protection against the dangers arising from exposure to ionising radiation.
The regulatory framework demonstrates that Euratom’s role has evolved beyond its original ambition of promoting nuclear industrial development.
It now performs important public safety and environmental protection functions within its treaty competences.
4.6. The continuing legal existence of Euratom
Unlike the ECSC, Euratom was not established for a limited period.
Its treaty remains in force.
The Treaty of Lisbon did not abolish Euratom or merge it completely into the European Union.
Instead, the treaty introduced amendments to the Euratom framework while preserving its separate legal identity and institutional arrangements.
Euratom and the European Union share institutions, including the European Commission, the Council, the European Parliament in its relevant supervisory role and the Court of Justice.
However, Euratom continues to operate under its own treaty.
This distinction is important for understanding the legal structure of European integration.
The Union and Euratom are closely connected, but their legal foundations are not identical.
The continued existence of Euratom demonstrates that European integration did not produce a complete merger of every historical Community into one legal entity.
5. The Merger Treaty of 1965: Institutional Consolidation of the Three Communities
The existence of three separate European Communities created an increasingly complicated institutional arrangement.
Although the ECSC, EEC and Euratom had different legal foundations and policy responsibilities, their activities were closely connected. They also shared important institutional arrangements, particularly the Parliamentary Assembly and the Court of Justice.
The existence of separate executive bodies and councils, however, created administrative duplication and made coordination more difficult.
The participating states therefore decided to consolidate the institutional structure without abolishing the separate legal identities of the three Communities.
5.1. The Treaty establishing a Single Council and a Single Commission
On 8 April 1965, the Member States signed the Treaty establishing a Single Council and a Single Commission of the European Communities, commonly known as the Merger Treaty or Brussels Treaty.
It entered into force on 1 July 1967.
The treaty established:
- A single Council serving the three Communities.
- A single Commission replacing their separate executive bodies.
- A more unified administrative structure.
- A common framework for institutional coordination.
Before the reform, the ECSC had its High Authority and Special Council of Ministers, while the EEC and Euratom had their own Commissions and Councils.
The Merger Treaty consolidated these executive and governmental structures.
An important historical clarification is necessary: the Parliamentary Assembly and the Court of Justice were already common institutions under the Convention on Certain Institutions Common to the European Communities, signed alongside the Treaties of Rome in 1957. The Merger Treaty did not create these common institutions; it completed the consolidation of the principal executive and Council structures.
5.2. The creation of the European Communities as a collective institutional system
Following the Merger Treaty, the three organisations were increasingly referred to collectively as the European Communities.
However, their separate treaty foundations continued to exist.
The distinction between institutional unity and legal identity is fundamental.
The ECSC, EEC and Euratom had a common institutional structure, but they did not become one legal entity simply because they shared a Commission and Council.
Each Community continued to operate within its respective treaty-based competences.
For example, a measure concerning the common agricultural policy would fall within the EEC framework, whereas a measure concerning nuclear safeguards would be adopted under the Euratom framework.
The applicable legal basis determined the institutional powers, legislative procedure and judicial framework governing the measure.
5.3. The significance of institutional consolidation
The Merger Treaty demonstrated that European integration could develop through institutional reform without requiring the complete unification of the participating legal entities.
It simplified administration, strengthened coordination and contributed to the development of a more coherent European institutional system.
It also established an important precedent for later reforms: the European Communities could progressively consolidate their institutions while retaining different legal competences and treaty arrangements.
This distinction would remain relevant throughout the subsequent development of the European Union.europarl.europa.eu+2
6. The Legal Relationship Between the Three Communities
Although the three Communities were established as separate organisations, they were never entirely isolated from one another.
Their relationship developed through common institutions, shared political objectives, treaty amendments and the gradual expansion of European integration.
Understanding their legal relationship requires distinguishing three different concepts: separate legal personality, common institutional arrangements and the development of a broader European legal order.
6.1. Separate legal personalities
The ECSC, EEC and Euratom were established through separate treaties.
Each possessed its own legal framework and defined institutional competences.
The European Coal and Steel Community exercised authority over the industries and activities covered by the Paris Treaty.
The European Economic Community exercised broader economic competences under the Treaty of Rome.
Euratom operated under its own treaty governing nuclear energy and related activities.
These separate foundations meant that the Communities were not simply departments of one overarching European organisation.
Each could exercise legal powers within its respective treaty framework.
The distinction was particularly important when determining which treaty provision authorised a particular institutional action.
6.2. Common institutions and institutional continuity
Despite their separate legal foundations, the Communities developed common institutional arrangements.
The Convention on Certain Institutions Common to the European Communities, signed in Rome in 1957, established common arrangements for the Parliamentary Assembly and Court of Justice.
The Merger Treaty subsequently created a single Commission and Council.
As a result, the three Communities operated through an increasingly unified institutional structure.
This arrangement produced an interesting constitutional situation.
The same institution could exercise different legal powers depending on the Community and treaty framework under which it was acting.
The Commission, for example, exercised responsibilities under the EEC Treaty and the Euratom Treaty, but the legal basis of its action determined the applicable rules and procedures.
Institutional unity therefore did not eliminate legal differentiation.
6.3. The relationship between Community law and national law
The development of the Communities also transformed the relationship between European rules and national legal systems.
The treaties established binding obligations for Member States, while the Court of Justice developed doctrines governing the legal effects of Community law within domestic legal systems.
The principles of direct effect and primacy became particularly important.
Direct effect allowed certain provisions of Community law to be invoked by individuals before national courts where the relevant legal conditions were satisfied.
Primacy established that conflicting national rules could not prevent the application of applicable Community law.
These principles were developed through judicial interpretation rather than being expressed in the original treaties in the same comprehensive form in which they are understood today.
They helped transform the Communities into an autonomous legal system.
6.4. The development of a common European legal order
The separate Communities increasingly became part of a wider process of European integration.
The EEC, in particular, developed an extensive body of legislation and case law.
Its regulatory activities affected trade, employment, agriculture, competition, transport, taxation and the movement of people and capital.
The Court of Justice also helped ensure that Community law was interpreted consistently across participating states.
Consequently, although the three Communities retained distinct legal foundations, they contributed to the development of a common European legal order.
This legal order would later become the foundation of the European Union.
7. The Maastricht Treaty and the Transformation of the European Communities
The Treaty on European Union, signed at Maastricht on 7 February 1992 and entering into force on 1 November 1993, fundamentally changed the structure of European integration.
It established the European Union as a broader political and legal framework.
However, the Maastricht Treaty did not immediately abolish the three Communities.
Instead, it established a relationship between the newly created European Union and the existing Community structures.
7.1. The European Community replaces the EEC
One of the most important changes was the renaming of the European Economic Community as the European Community.
This change reflected the expansion of European integration beyond purely economic objectives.
The Community increasingly exercised responsibilities in areas such as consumer protection, environmental policy, public health, education and other fields established by the treaties.
The change in terminology therefore reflected a broader evolution in the legal and political character of European integration.
The European Community continued to possess legal personality and retained its own treaty-based competences.
7.2. The three-pillar structure and the continued existence of Euratom and ECSC
Under Maastricht, the European Union operated through three pillars.
The first pillar consisted of the European Communities, including the European Community and Euratom, while the second and third pillars concerned foreign and security policy and justice and home affairs.
The ECSC also continued to exist as a separate Community under its own treaty.
This distinction is important because the establishment of the European Union did not immediately transform every pre-existing Community into a single legal organisation.
The three Communities continued to have different treaty foundations, although they operated within an increasingly integrated political and institutional framework.
7.3. The expiration of the ECSC and the continued existence of Euratom
The ECSC Treaty expired on 23 July 2002, fifty years after entering into force.
Its remaining activities and financial arrangements were addressed through the wider European Community framework and the protocol concerning the financial consequences of the expiration of the ECSC Treaty and the Research Fund for Coal and Steel.
Euratom, by contrast, continued to operate under its own treaty.
This difference is fundamental to understanding the present legal structure.
The ECSC was a time-limited experiment in sectoral integration. Euratom was established without a comparable fifty-year termination clause and remains legally active.
7.4. The Treaty of Lisbon and the disappearance of the European Community
The Treaty of Lisbon, which entered into force on 1 December 2009, brought about another major constitutional transformation.
It abolished the formal pillar structure and established the European Union as the successor to the European Community.
Article 1 TEU provides that the Union replaces and succeeds the European Community.
The European Union acquired express legal personality under Article 47 TEU.
The EEC and the European Community therefore no longer exist as separate legal entities.
However, the Euratom Treaty was not incorporated into the Treaty on European Union or the Treaty on the Functioning of the European Union.
Instead, Euratom retained its separate treaty framework and legal personality.
This means that the modern European legal order includes the European Union and the European Atomic Energy Community, which share institutions but remain distinct legal entities.
The historical transition can be summarised as follows:
1952–1958: Three separate Communities
ECSC
Coal and steel
EEC
Common market
Euratom
Nuclear energy
Merger Treaty: common executive and Council structures
1993–2002: European Union and Communities
European UnionBroader political and legal framework
European CommunityFormer EEC
EuratomSeparate treaty
ECSC remains separate until 2002
Lisbon Treaty – 2009
Present legal structure
European UnionTEU and TFEU
Active
EuratomSeparate Euratom Treaty
Active
Simplified institutional and legal evolution. The ECSC expired in 2002; the European Community was succeeded by the EU in 2009.
The result is a legal structure that preserves the historical significance of the founding Communities while reflecting the more unified institutional framework of the modern European Union.EUR-Lex+2
8. The Constitutional and Legal Significance of the Founding Communities
The three founding Communities were important not only because of their economic achievements but also because they introduced institutional and legal principles that fundamentally influenced the development of European public law.
Their establishment marked the beginning of a new form of international cooperation in which states accepted that certain public powers could be exercised through institutions operating independently of national governments.
This development raised fundamental questions concerning sovereignty, democratic legitimacy, judicial authority and the relationship between international and domestic law.
8.1. The development of supranational authority
The ECSC, EEC and Euratom demonstrated that an international organisation could possess institutions with powers extending beyond conventional diplomatic coordination.
The High Authority of the ECSC was particularly significant because it could adopt binding decisions within its treaty competences.
The EEC subsequently developed a more extensive legislative system, while Euratom established a specialised regulatory framework.
The resulting model combined national governmental participation with independent European decision-making.
This became one of the defining characteristics of supranational governance.
8.2. The emergence of an autonomous European legal order
The Communities also created the conditions for the development of a legal system distinct from traditional international law.
Two judgments of the Court of Justice are particularly important.
Van Gend en Loos v Nederlandse Administratie der Belastingen (Case 26/62, 1963)
The case concerned the interpretation of a provision of the EEC Treaty prohibiting Member States from introducing new customs duties or increasing existing ones.
The Court recognised that Community law constituted a new legal order under which individuals could acquire rights that national courts were required to protect.
This principle became known as direct effect.
Costa v ENEL (Case 6/64, 1964)
The case concerned the relationship between Community law and conflicting national legislation.
The Court established that the Member States had accepted limitations on the exercise of their sovereign rights within the fields covered by Community law and that subsequent national legislation could not override applicable Community obligations.
This judgment became the foundation of the principle of primacy, also known as supremacy, of EU law.
These judgments were central to the constitutional development of the Communities.
They demonstrated that European integration was not merely a political agreement between governments. It was also a legal system operating within national jurisdictions.
8.3. The importance of treaty-based competences
The three Communities were established through treaties that defined their objectives, institutions and powers.
Their authority was therefore limited by the competences conferred upon them by the participating states.
This principle remains fundamental to the modern European Union.
Under the principle of conferral, the Union may act only within the competences attributed to it by the Member States through the treaties.
The original Communities therefore established an important constitutional principle: supranational authority could be exercised independently, but only within a legally defined mandate.
8.4. Institutional balance and the distribution of powers
The institutional architecture of the founding Communities also contributed to the development of the principle of institutional balance.
The Commission, Council, Parliamentary Assembly and Court of Justice performed different functions within the common legal framework.
The Commission represented the general interests of the Community, the Council represented national governments, the Assembly provided parliamentary supervision and the Court ensured legality.
Although their powers were not equivalent, the institutional structure demonstrated that supranational governance required a distribution of responsibilities between different bodies.
The modern European Union retains this principle, although its institutions have evolved considerably.
8.5. The development of European citizenship and individual rights
The founding Communities were initially concerned primarily with economic integration.
Nevertheless, their legal development increasingly affected individuals directly.
Workers, businesses and other economic actors acquired rights under Community law, while national courts became responsible for protecting certain European legal entitlements.
The introduction of European Union citizenship through the Maastricht Treaty represented a further stage in this development.
The transformation from economic cooperation to a broader system of individual rights was one of the most important consequences of the original Community framework.
8.6. The constitutional significance of Euratom’s continued existence
Euratom occupies a particularly interesting position in the contemporary European legal system.
Its continued existence demonstrates that the integration of European institutions does not necessarily require the complete unification of all legal entities operating within the European framework.
Euratom shares important institutions with the European Union, but its legal authority continues to derive from a separate treaty.
This arrangement is an example of differentiated institutional and legal integration.
It also demonstrates why an understanding of the historical Communities remains necessary when examining contemporary EU institutional law.
9. The Three Founding Communities Compared
The following comparison identifies the principal differences between the three Communities and their respective contributions to European integration.
| Legal characteristic | ECSC | EEC | Euratom |
|---|---|---|---|
| Founding treaty | Treaty of Paris | Treaty of Rome | Treaty of Rome |
| Signed | 1951 | 1957 | 1957 |
| Entered into force | 1952 | 1958 | 1958 |
| Founding members | Six states | Six states | Six states |
| Principal objective | Coal and steel market | General economic integration | Peaceful nuclear cooperation |
| Original executive institution | High Authority | Commission | Commission |
| Council structure | Special Council of Ministers | Council | Council |
| Parliamentary body | Common Assembly | Parliamentary Assembly | Parliamentary Assembly |
| Judicial institution | Court of Justice | Court of Justice | Court of Justice |
| Legal personality | Yes | Yes | Yes |
| Present status | Expired in 2002 | Succeeded by EU in 2009 | Continues separately |
The principal differences in their economic and legal functions
The ECSC was a sectoral economic community.
It concentrated on strategic industrial production and established a common market in coal and steel.
Its principal historical contribution was demonstrating that independent supranational institutions could exercise binding regulatory powers within a defined economic sector.
The EEC was a general economic integration community.
It established the foundations for the common market, the customs union, common policies and the four fundamental freedoms.
Its legal framework became the most influential foundation of the modern European internal market.
Euratom was a specialised technological and regulatory community.
It focused on nuclear research, the peaceful use of nuclear energy, safeguards, supply arrangements and radiation protection.
Its separate legal identity continues to exist alongside the European Union.
These differences explain why the three Communities should not be treated as interchangeable organisations, even though they formed part of the same historical integration process.
10. The Founding Communities in Contemporary European Union Law
Although two of the three original Communities no longer exist as separate legal entities, their legal and institutional contributions remain relevant.
The modern European Union continues to operate through a treaty-based legal system whose foundations were established during the first decades of European integration.
The original Community treaties influenced the structure of the Treaty on European Union and the Treaty on the Functioning of the European Union.
Their institutional arrangements also contributed to the development of the present European Commission, European Parliament, Council and Court of Justice.
The continuing relevance of the ECSC
The ECSC no longer exists, but its historical influence remains visible in the principles of supranational governance, common market regulation and institutional independence.
Its former treaty competences were absorbed into the broader European Community framework, while its remaining assets and financial arrangements were addressed through the Research Fund for Coal and Steel.
The continuing relevance of the EEC
The EEC is no longer a separate legal entity, but its legal and economic achievements remain central to EU law.
The internal market, customs union, common commercial policy, competition law and the four fundamental freedoms developed from the framework established by the Treaty of Rome.
Many provisions of the original EEC Treaty were amended, renumbered and incorporated into the Treaty on the Functioning of the European Union.
The historical connection remains particularly evident in the development of Articles 26–66 TFEU, which govern the internal market and its fundamental freedoms.
The continuing relevance of Euratom
Euratom continues to operate under its own treaty.
Its legal framework remains important for nuclear safety, radiation protection, nuclear safeguards, research cooperation and the regulation of nuclear materials.
It is therefore not merely a historical institution.
It remains an active component of the wider European legal framework.
The founding Communities as a model of European integration
The three Communities demonstrate how European integration developed through a combination of sectoral cooperation, general economic integration and specialised technological regulation.
Their separate legal identities, common institutions and successive treaty reforms established a model of governance that remains distinctive in contemporary international law.
They also illustrate a broader principle of European constitutional development: integration can advance through the gradual pooling of specific competences without requiring the immediate creation of a single federal state.
The founding Communities therefore remain essential to understanding both the historical origins and the contemporary operation of European Union law.
11. Key Takeaways
1. The European Union developed from three separate Communities established through international treaties: the ECSC, EEC and Euratom.
2. The European Coal and Steel Community was established by the Treaty of Paris, signed in 1951 and effective from 23 July 1952.
3. The ECSC was the first major supranational European organisation and introduced an independent High Authority capable of adopting binding decisions.
4. The European Economic Community and Euratom were established through separate Treaties of Rome, signed on 25 March 1957 and effective from 1 January 1958.
5. The EEC sought to establish a common market, customs union and broader economic integration through the development of the four fundamental freedoms.
6. Euratom was established to promote peaceful nuclear energy, scientific cooperation, nuclear safeguards and common safety standards.
7. The three Communities possessed separate legal foundations and legal personalities, although they developed common institutional arrangements.
8. The Merger Treaty of 1965, effective from 1967, established a single Commission and Council for the three Communities. The Parliamentary Assembly and Court of Justice were already common institutions.
9. The Maastricht Treaty transformed the EEC into the European Community and established the broader European Union, while the ECSC and Euratom initially retained their separate legal identities.
10. The ECSC Treaty expired on 23 July 2002, after its fifty-year duration.
11. The Treaty of Lisbon abolished the formal pillar structure and established the European Union as the legal successor to the European Community.
12. Euratom continues to exist under its own treaty and retains a separate legal personality, despite sharing important institutions with the European Union.
13. The founding Communities established the institutional and legal foundations for the modern European legal order, including the development of direct effect, primacy and supranational governance.
12. Frequently Asked Questions
1. What were the three founding Communities of the European Union?
The three founding Communities were the European Coal and Steel Community (ECSC), the European Economic Community (EEC) and the European Atomic Energy Community (Euratom). They were established through the Treaty of Paris of 1951 and the two Treaties of Rome of 1957.
2. Which European Community was established first?
The ECSC was established first. Its founding treaty was signed on 18 April 1951 and entered into force on 23 July 1952. It represented the first major institutional experiment in supranational European integration.
3. What was the difference between the ECSC and the EEC?
The ECSC concentrated on coal and steel production, establishing a common market in strategically important industrial resources. The EEC pursued broader economic integration, including a customs union, a common market and common policies covering a much wider range of economic activities.
4. Why was Euratom established?
Euratom was established to promote the peaceful development and use of nuclear energy through scientific cooperation, research, nuclear safeguards, common safety standards and the development of a European nuclear industry.
5. Were the three European Communities separate legal entities?
Yes. Each Community was established through a separate treaty and possessed its own legal personality and defined competences. They nevertheless shared important institutional arrangements, which were progressively consolidated through the Merger Treaty.
6. Did the Merger Treaty combine the three Communities into one organisation?
No. The Merger Treaty, signed in 1965 and effective from 1967, consolidated their principal executive and Council structures by creating a single Commission and a single Council. It did not eliminate their separate legal personalities or treaty foundations.
7. What happened to the European Coal and Steel Community?
The ECSC Treaty expired on 23 July 2002, following its fifty-year duration. Its remaining activities and financial arrangements were transferred into the broader European Community framework, including the establishment of the Research Fund for Coal and Steel.
8. Does the European Economic Community still exist?
No. The EEC was renamed the European Community under the Maastricht Treaty. Following the entry into force of the Treaty of Lisbon in 2009, the European Union replaced and succeeded the European Community.
9. Does Euratom still exist?
Yes. Euratom continues to operate under its own treaty, which remains in force. It has a separate legal personality and shares important institutions with the European Union.
10. Is Euratom part of the European Union?
Euratom is closely connected with the EU institutional framework, but it is not simply another name for the European Union. It remains a separate legal entity governed by its own treaty. Its membership is the same as that of the EU.
11. Which of the founding Communities contributed most to modern EU law?
The EEC made the broadest contribution to the development of modern EU law because its common market framework generated extensive legislation and judicial doctrines concerning trade, competition, establishment, services, employment and the movement of capital and persons. However, the ECSC was fundamental in establishing the supranational institutional model, while Euratom continues to provide a specialised legal framework.
12. What is the relationship between the founding Communities and the present European Union?
The ECSC and EEC no longer exist as separate legal entities. The European Union succeeded the European Community in 2009, incorporating its principal legal and institutional framework. Euratom, however, continues separately under its own treaty, while sharing important EU institutions.
13. What is the significance of the founding Communities for constitutional law?
The founding Communities demonstrated that states could confer defined public powers on independent supranational institutions. Their development established the foundations of the European legal order, including the principles of direct effect, primacy, institutional balance and the allocation of competences.
13. Conclusion
The establishment of the ECSC, EEC and Euratom represents the decisive institutional beginning of European integration.
Although the three Communities were created for different purposes, they shared a common political and legal ambition: to replace traditional forms of European rivalry with structured cooperation based on common rules, permanent institutions and binding legal commitments.
The ECSC demonstrated that states could place strategically important economic sectors under the supervision of an independent European authority. The EEC expanded this experiment into a general economic framework, establishing the foundations of the common market and the four fundamental freedoms. Euratom developed a specialised system of cooperation in nuclear research, energy regulation, safeguards and public safety.
Their institutional development was equally important. The creation of common parliamentary and judicial institutions, followed by the consolidation of the Commission and Council through the Merger Treaty, established the foundations of a coherent European institutional system.
Nevertheless, the three Communities should not be understood as three successive names for the same organisation. They possessed separate legal identities, different competences and distinct treaty frameworks. Their institutional cooperation did not immediately eliminate these legal differences.
The Maastricht Treaty subsequently created the European Union as a broader political and legal structure, while the Treaty of Lisbon established the Union as the successor to the European Community. Euratom, however, retained its separate legal personality and continues to operate under its own treaty.
The historical significance of these developments extends beyond the institutional history of Europe. The founding Communities helped create a new model of legal authority in which sovereign states participate in a common system capable of producing binding rules, protecting individual rights and influencing the operation of national legal systems.
The modern European Union cannot be fully understood without recognising this historical and constitutional inheritance.
The three Communities were not merely the predecessors of the Union. They were the institutional foundations upon which its distinctive legal order was constructed.
Principal legal and historical sources
The following official sources provide the documentary foundation for this article.
1. Treaty establishing the European Coal and Steel Community – EUR-Lex – Original treaty establishing the ECSC.
2. Treaty establishing the European Economic Community – EUR-Lex – Original Treaty of Rome establishing the EEC.
3. Treaty establishing the European Atomic Energy Community – EUR-Lex – Founding treaty of Euratom.
4. Treaties of the European Union – EUR-Lex – Historical development and legal significance of the founding treaties.
5. Founding Agreements – European Union – Official historical account of the founding agreements and subsequent treaty reforms.
6. Merger Treaty – European Parliament – Institutional consolidation of the three Communities.
7. Treaty of the European Atomic Energy Community – EUR-Lex – Legal status and continuing existence of Euratom.
8. Nuclear Energy – European Commission – Contemporary European nuclear energy policy and regulatory framework.
9. Treaty History – Council of the European Union – Historical development of European institutions and treaty structures.
Principal judgments:
- Van Gend en Loos v Nederlandse Administratie der Belastingen, Case 26/62 (1963).
- Flaminio Costa v ENEL, Case 6/64 (1964).
- Internationale Handelsgesellschaft mbH v Einfuhr- und Vorratsstelle für Getreide und Futtermittel, Case 11/70 (1970).
Principal legal instruments:
- Treaty of Paris (1951).
- Convention on Certain Institutions Common to the European Communities (1957).
- Treaty establishing the EEC (1957).
- Treaty establishing Euratom (1957).
- Merger Treaty (1965).
- Treaty on European Union (Maastricht, 1992).
- Treaty of Lisbon (2007).
- Protocol on the financial consequences of the expiry of the ECSC Treaty and on the Research Fund for Coal and Steel.
The information provided in this article ("The Founding Communities: The ECSC, EEC, and Euratom") is for general educational and informational purposes only and does not constitute formal legal advice. Reading this content does not create an attorney-client relationship. Laws vary by jurisdiction; consult a licensed attorney for specific legal matters.
Tsvety, LL.M., M.A.
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