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Sources of European Union law

There are three sources of European Union law: primary law, secondary law and supplementary law.
The main sources of primary law are the Treaties establishing the European Union.
Secondary sources are legal instruments based on the Treaties and include unilateral secondary law and conventions and agreements.
Supplementary sources are elements of law not provided for by the Treaties. This category includes Court of Justice case-law, international law and general principles of law.

There are three sources of European Union (EU) law: primary sources, secondary sources and supplementary law.

Sources of primary law

Primary sources, or primary law, come mainly from the founding Treaties, namely the Treaty on the EU and the Treaty on the Functioning of the EU. These Treaties set out the distribution of competences between the Union and the Member States and establishes the powers of the European institutions. They therefore determine the legal framework within which the EU institutions implement European policies.

Moreover, primary law also includes:

  • the amending EU Treaties;
  • the protocols annexed to the founding Treaties and to the amending Treaties;
  • the Treaties on new Member States’ accession to the EU.

Sources of secondary law

Secondary law comprises unilateral acts and agreements.

Unilateral acts can be divided into two categories:

  • those listed in Article 288 of the Treaty on the Functioning of the EU: regulations, directives, decisions, opinions and recommendations;
  • those not listed in Article 288 of the Treaty on the Functioning of the EU, i.e. "atypical" acts such as communications and recommendations, and white and green papers.

Convention and Agreements group together:

  • international agreements, signed by the EU and a country or outside organisation;
  • agreements between Member States; and
  • interinstitutional agreements, i.e. agreements between the EU institutions.

Sources of supplementary law

Besides the case law of the Court of Justice, supplementary law includes international law and the general principles of law. It has enabled the Court to bridge the gaps left by primary and/or secondary law.

International law is a source of inspiration for the Court of Justice when developing its case law. The Court cites written law, custom and usage.

General principles of law are unwritten sources of law developed by the case law of the Court of Justice. They have allowed the Court to implement rules in different domains of which the treaties make no mention.

Last updated: 18.08.2010
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