The first European Treaty, the one establishing the European Coal and Steel Community (ECSC), was signed in Paris on 18 April 1951 by France, Germany, Italy and the Benelux countries and entered into force on 23 July 1952. Its main objective was to eliminate the various barriers to trade and to create a common market in which coal and steel products from the Member States could move freely in order to meet the needs of all Community inhabitants, without discrimination on grounds of nationality. Capital and workers in both sectors should also circulate freely. In order that all this could be achieved, the Treaty laid down certain rules on investment and financial aid, on production and prices, on agreements and concentrations of businesses and on transport. These rules were to be implemented by Community institutions, which would exercise the powers previously held by the states in those sectors: namely a High Authority and a special Council (of Ministers), the decisions of which would be binding on all Member States. Ambitious despite its restricted scope, the ECSC Treaty instituted a European Assembly and a European Court of Justice. The avowed intentions of the founders of the ECSC were, indeed, that it should be an experiment, which could gradually be extended to other economic spheres, culminating in a "European Federation". For this reason, the duration of the ECSC Treaty was limited to fifty years. On 23 July 2002, when it expired, the specific rules concerning the coal and steel sectors were integrated in the Community law and their particular resources, programmes and international obligations were taken over by the European Community [Decisions 2002/234, 2002/595, 2002/596, 2003/76 and 2003/77]. The coal and steel sectors, previously covered by the ECSC Treaty, are dealt with respectively in the chapters on energy and industry.
The Treaty establishing the European Atomic Energy Community (EAEC, but more commonly known as Euratom) was signed in Rome on 25 March 1957 and came into force on 1 January 1958. Its aim was to create a common market for nuclear materials and equipment, establish common nuclear legislation, introduce a common system for supplies of fissile materials and establish a system for supervising the peaceful use of nuclear energy and common standards for nuclear safety and for the health and safety protection of the population and workers against ionising radiation. The key elements in this Treaty were, however, the coordination of the Member States’ research programmes and a joint research programme, implemented in a Joint Research Centre, which was to develop technology and stimulate nuclear production in Europe [see sections 18.2.4 and 18.3]. Although it was very much in the spotlight at the time of its establishment, Euratom has experienced many ups and downs as a result both of disillusionment as regards nuclear energy’s economic prospects and of the ambition of some Member States to develop their own nuclear industry, and not purely for civil purposes. Nevertheless, the EAEC Treaty is still in force and manages quite well the nuclear energy sector of the Community/Union. The subjects concerning it are examined mainly in the chapters on research and energy.
Signed at the same time as the Euratom Treaty on the Capitol Hill in Rome on 25 March 1957, the Treaty establishing the European Economic Community (EEC) was likewise brought into force on 1 January 1958. Although the EEC and EAEC treaties are sometimes referred to as the "Treaties of Rome", the "Treaty of Rome" is obviously the EEC Treaty. The essential task, which the Treaty of Rome assigned to the Community institutions, was the creation of a common market between the Member States. That involved: (a) the achievement of a customs union entailing, on the one hand, the abolition of customs duties, import quotas and other barriers to trade between Member States and, on the other hand, the introduction of a Common Customs Tariff (CCT) vis-à-vis third countries [see chapter 5]; and (b) the implementation, inter alia through common policies, of four fundamental freedoms: freedom of movement of goods, of course, but also freedom of movement of salaried workers, freedom of establishment and freedom to provide services by independent persons and companies and, finally, freedom of capital movements [see chapter 6].
Although in the preamble to the EEC Treaty the Member States declared that they were determined to lay the foundations of an ever closer union among the peoples of Europe, the Treaty itself constituted the charter for a common market. It set the objectives to be attained so as to arrive at that stage of European integration. However, through its Article 235 [Article 308 TEC = Article 352 TFEU], it gave Member States the possibility to act in the fields not provided by it by taking unanimously the measures required to attain one of its objectives. This allowed the Member States to implement a large number of common or, so called, Community policies without amending the Treaty.
Nevertheless, the EEC Treaty had a serious fault: although it had set a timetable for the abolition of customs barriers to trade, it had not done the same for the removal of trade barriers of equivalent effect. This vacuum was covered by the Single European Act, which came into force on 1 July 1987. Supplementing the EEC Treaty, the Single Act committed the Community to adopt measures with the aim of progressively establishing the internal market over a period expiring on 31 December 1992. At the same time it consecrated the European Council, European cooperation on foreign policy and social and economic cohesion between Member States. Lastly, it served as a legal base for numerous common policies, notably, social, environmental, research and technology.
The Treaties of Paris and Rome each set up different executive organs. The latter were merged by the Treaty of 8 April 1965 establishing a single Council and a single Commission of the European Communities, in order to better manage the expanding common policies. Since 1 July 1967 there has therefore been only a single Council of Ministers and a single Commission, with the latter inheriting the powers of the ECSC High Authority, of the EEC Commission and of the Euratom Commission.
The Treaties establishing the Communities were amended to some extent, notably as regards their provisions relating to the functioning of the institutions, by the Treaty concerning the Accession to the European Economic Community of Denmark, Ireland, the United Kingdom and Norway. That Treaty was signed in Brussels on 22 January 1972 and brought into force on 1 January 1973, but only for three countries, as a referendum in Norway had ruled out that country's accession.
In parallel with the creation of the Community's own resources by the Decision of 21 April 1970 [see section 3.4], the Member States agreed to amend the Treaties in order to increase the European Parliament's budgetary powers. In fact, a first Budget Treaty was signed on 22 April 1970 and entered into force on 1 January 1971, but the European Parliament felt that it did not increase its powers sufficiently. The Commission decided that the Parliament was right and put forward proposals for a further extension of the Parliament's budgetary powers. The second Budget Treaty, which governs the Community finances, was the result. That Treaty was signed on 22 July 1975 and entered into force on 1 June 1977. In addition to the creation of a new institution, the Court of Auditors, it conferred on the European Parliament the exclusive right to give a discharge to the Commission in respect of the implementation of the budget and, "if there are important reasons", to reject the budget as a whole [see section 4.1.3].
The Treaties establishing the Communities were once again amended as to their institutional clauses, by the Treaty concerning the Accession of the Hellenic Republic to the European Economic Community and to the European Atomic Energy Community, signed in Athens on 28 May 1979. By that Treaty the "Nine" became "Ten" from 1 January 1981. They became "Twelve" as from 1 January 1986 by virtue of the Acts of Accession of Spain and Portugal, signed in Madrid and Lisbon respectively on 12 June 1985.
Since the 1st January 1995, the Europe of Twelve became the Europe of Fifteen, with the accession of Austria, Finland and Sweden. The greatest enlargement of the European Community/Union came in 2004 with the accession of Poland, Hungary, the Czech Republic, Slovakia, Slovenia, Estonia, Latvia, Lithuania, Cyprus and Malta. With the accessions of Bulgaria and Romania, on 1 January 2007, and of Croatia, on 1 July 2013, we now speak of the Union of Twenty-eight.