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European Union: Primary law

A guide to researching the law of the EU

Abourt primary law

Primary law, also known as the primary or original source of law, can be seen as the supreme source of law in the European Union (EU). It is at the apex of the European legal order. It consists mainly of the founding treaties of the European Union.

The primary law concerns also:

  • the major Treaties amending the EU;
  • the Protocols annexed to those Treaties;
  • additional Treaties making changes to specific sections of the founding Treaties;
  • the Treaties of accession of new Member States to the EU.

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Official Journal of the European Union

The founding Treaties (original versions and later updatings), the amending Treaties and the Accession Treaties for each of the six enlargements are published in the Official Journal of the European Union. You will find the Official Journal in the European Documentation Centre from 1992 - 1997.

EUR-Lex  contains electronic copies of all Official Journals since the first edition. Effective 1 July 2013, the electronic edition of the OJ (e-OJ) is authentic and produces legal effects.

Databases and websites

From the page Treaties in Eur-Lex you can access the basic legal texts on which the European Union and the European Communities are founded: the founding Treaties (original versions and later updatings), the amending Treaties, the Accession Treaties for each of the six enlargements, plus other essential documents.


The site EU Treaties gives you access to the full text of the main treaties with additional information.

The European Union Constitution brings together facts, official documents, analysis, bibliographies, links and other resources relevant to the main steps in the European constitutional process.

See for yourself below.