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European Union Law

EU Treaties

The European Union is based on the rule of law. Every action taken by the EU is founded on treaties that have been approved voluntarily and democratically by all EU member countries. EU treaties are binding agreements between EU member countries. They include founding treaties, amending and accession treaties, and protocols. Treaties set out EU objectives, rules for EU institutions, how decisions are made and the relationship between the EU and its member countries. Every action taken by the EU is founded on treaties. Under the treaties, EU institutions can adopt legislation, which the member countries then implement. 

All EU treaties are available in the EUR-Lex Treaties collection (open access) and are published in the Official Journal of the European Union on Eur-Lex (open access). The Eur-Lex Treaties collection can be browsed or searched, and there is a handy Chronological Overview. The treaties in the Treaty Collection link to the treaties in the Official Journal.

See the EU's Treaties page for a list of the main EU Treaties and links to the full text.


The founding treaties provide the legal basis for the European Union, and are frequently referred to as 'primary legislation'. The founding treaties are:

International Agreements

The Eur-Lex International Agreements collection covers all the instruments produced by the EU in the exercise of its international responsibilities:

  • agreements concluded by the European Union with non-member countries or with international organisations in their specific areas of responsibility
  • agreements concluded jointly by the Member States and the European Union in areas of shared responsibility (‘mixed type’ agreements)
  • decisions of joint committees set up pursuant to an international agreement and comprising representatives of the signatories for the purpose of administering the agreement.

The database can be browsed or searched.

Recent articles on EU Treaties

Open-access full text on SSRN

Shaw, Jo, 'The European Union and Global Constitutionalism' (January 30, 2017) (chapter in forthcoming book - Anthony F Lang, and Antje Wiener (eds), Handbook on Global Constitutionalism (Edward Elgar, 2017)

Abstract: This chapter examines narratives of constitutionalism and the ebb and flow of constitutional ideas and practices within and across the European Union and its Member States from the inception of the treaties to the present day. It seeks to establish to what extent the European Union manifests a ‘constitutional’ legal and political order. It focuses on the contribution of legal rules to developing constitutional structures, as well as the role of ideas in relation to legal rules. The original objectives of the so-called ‘founding fathers’ of European integration concerned the promotion of peace, prosperity and a form of non-nationalist supranationalism. In many respects, the EU has been remarkably successful, given the history of the European continent right through to the middle of the twentieth century. The ‘constitutionalised treaties’ have been at the heart of that success. But now we must pay attention to recent challenges, resulting from the financial crisis, the travails of the Eurozone, problems in the EU’s near abroad, and the arrival of large numbers of refugees at and beyond the external borders of the EU. In an era of national reactions against neo-liberalism and globalisation, the role of the EU and specifically of the Court of Justice of the EU is increasingly under question.