Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

European Union Law: Institutions and Sources

This guide provides an overview of the structure and lawmaking activities of the EU Institutions as well as resources for EU research.

The Treaty of Lisbon

The Treaty of Lisbon (initially known as the Reform Treaty) is an international agreement that amends the treaties governing the European Union. The Lisbon Treaty was signed by the EU member states on 13 December 2007, and entered into force on 1 December 2009. It amends the Treaty of European Union (more commonly known as the Maastricht Treaty) and the Treaty establishing the European Union (the Treaty of Rome). In this process, the Rome Treaty was renamed to the Treaty of the Functioning of the European Union (TFEU).

For detailed information about the Treaty of Lisbon and access to the full text, click here.

The Founding Treaties

The text of the treaties are published in the Official Journal of the European Union, the official gazette of the EU. Other treaty series and commercial publications described below are also sources for the text of the EU treaties.

The founding treaties are frequently referred to as “primary legislation.” In contrast, “secondary legislation” refers to directives, regulations and other forms of law described later in the section on Legislation.  To access the text of the treaties listed below, click here.

Following is a list of the founding treaties that provide the legal basis for the EU:

  • Treaty Establishing the European Coal and Steel Community, Apr. 18, 1951, 261 U.N.T.S. 140 (ECSC Treaty or Treaty of Paris). This treaty expired by its own terms on July 23, 2002.
  • Treaty Establishing the European Economic Community, Mar. 25, 1957, 298 U.N.T.S. 3, 4 Eur. Y.B. 412 (EEC Treaty or Treaty of Rome).
  • Treaty Establishing the European Atomic Energy Community, Mar. 25, 1957, 298 U.N.T.S. 259, 5 Eur. Y.B. 454 (Euratom Treaty).
  • Treaty Establishing a Single Council and a Single Commission of the European Communities, Apr. 8, 1965, 1967 J.O. 152/1 (Merger Treaty).
  • Single European Act, Feb. 17, 1986, 1987 O.J. (L 169) 1, 25 I.L.M. 506.
  • Treaty on European Union, Feb. 7, 1992, 1992 O.J. (C 191) 1, 31 I.L.M. 253 (Union Treaty or Maastricht Treaty).
  • Treaty of Amsterdam Amending the Treaty on European Union, the Treaties Establishing the European Communities and Certain Related Acts, Oct. 2, 1997, 1997 O.J. (C 340) 1, 37 I.L.M. 56 (Treaty of Amsterdam).
  • Treaty of Nice Amending the Treaty on European Union, the Treaties Establishing the European Communities and Certain Related Acts, Feb. 26, 2001, 2001 O.J. (C 80) 1 (Treaty of Nice). 

Consolidated versions of the treaties incorporating the changes through the Treaty of Nice are available in the Official Journal of the European Union:

  • Treaty on European Union, 2006 O.J. (C 321) 5.
  • Treaty Establishing the European Community, 2006 O.J. (C 321) 37.

The Treaty of Amsterdam renumbered the articles of the founding treaties. Citations to specific articles of the founding treaties prior to the ratification of the Treaty of Amsterdam in 1997 will be to the old numbering scheme of the treaty articles. For example, the article on the creation of the internal market is cited as Article 14 (ex Art. 7a). The ex number refers to the numerical sequence of the treaty articles prior to the Treaty of Amsterdam. A table of equivalences showing the correspondence between the old and new numbering scheme was published in the Official Journal on October 11, 1997.

Accession Treaties

The EU has grown since its founding by admitting additional nations. New members of the EU must sign and ratify an accession treaty in order to join the EU. To access the full text of these treaties, click here.

  • Accession to the European Communities of the Kingdom of Denmark, Ireland, and the United Kingdom of Great Britain and Northern Ireland, Jan. 22, 1972, 1972 O.J. (L 73) 5 (First Accession Treaty).
  • Accession to the European Communities of the Hellenic Republic, May 28, 1979, 1973 O.J. (L 291) 9 (Second Accession Treaty).
  • Accession to the European Economic Communities of the Kingdom of Spain and the Portuguese Republic, June 12, 1985, 1985 O.J. (L 302) 9 (Third Accession Treaty).
  • Accession to the European Union of the Republic of Austria, the Republic of Finland, and the Kingdom of Sweden, June 24, 1994, 1994 O.J. (C 241) 9 (Fourth Accession Treaty).
  • Treaty concerning the Accession of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia, and the Slovak Republic to the European Union, April 16, 2003, 2003 O.J. (L 236) 33
  • Treaty concerning the Accession of the Republic of Bulgaria and Romania, April 25, 2005, 2005 O.J. (L 157) 11