Why do the EU treaties matter?

The EU has developed through a series of treaties that define its rules.

They also define the institutions that carry out the work of the EU.

These treaties must be agreed by each member country, and when ratified according to its own national processes establish the basic rules and institutions that the union needs to function, and which members are expected to follow.

The key treaties in the development of the EU (including the dates they were signed) are set out below.

The Treaty of Rome (signed 1957, entered into force 1958)
This Treaty established the European Economic Community (EEC), the forerunner of the EU with six original members.

The Single European Act (signed 1986, entered into force 1987)
This treaty was designed to give the power to the EEC to make laws in areas that supported the goal of free flow of goods and services across Europe.

The Maastricht Treaty (signed 1992, entered into force 1993)
The Maastricht Treaty established the European Union which encompasses the European Community and co-operation in common foreign and security policy and justice and home affairs. The Treaty also established the groundwork for a single European currency.

There have been other treaties, such as Amsterdam (signed 1977, entered into force 1999) and Nice (signed 2001, entered into force 2003), which address particular issues and amend previous treaties.

The proposed Constitutional Treaty (signed 2004)
At the end of 2004 the governments of member states agreed a new treaty, known as the Constitutional Treaty, designed to rationalise and streamline the operation of the union. The Constitutional Treaty would have replaced all existing EU treaties and re-founded the EU.

The Treaty was ratified by Austria, Cyprus, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Malta, Slovakia, Slovenia and Spain. The French and Dutch people voted against ratification of the Treaty on 29 May and 1 June 2005 respectively. The Treaty required the ratification of all member states in order to come into force.

The Lisbon Treaty (signed 2007)
The Lisbon Treaty will make the changes needed for an EU of 27 to work more effectively. It will allow the EU to move on from debating institutional changes and focus on issues which matter to citizens: energy security, organised crime and terrorism, globalisation, further enlargement and making Europe’s voice more effective internationally.

The mandate for a new Treaty was agreed by the leaders of all 27 EU member states at the European Council on June 2007. The Lisbon Treaty is not a free-standing document, like the Constitutional Treaty, but instead like the Single European Act and the Treaties of Maastricht, Nice and Amsterdam, will only amend existing EU Treaties.

The Lisbon Treaty will have to be ratified by all Member States according to their own constitutional procedures. As with all Treaties, the UK Parliament must be satisfied that it is in the national interest, before it can be implemented in national law.

Read more here about why the Lisbon Treaty matters and what it means for the UK.