Multi-speed Europe

The multi-speed Europe concept has been debated for years in European political circles, as a way to solve some institutional issues. The concept is that the more members there are in the Union, the more difficult it becomes to reach consensus on various topics, and the less likely it is that all would advance at the same pace in various fields.

Intermediate forms could be limited to some areas of close cooperation, as some historical examples are given below. It is also possible now for a minimum of eight EU member states to use enhanced co-operation, but this new framework has been used only once. A second proposal, a unified European patent, is nearing completion with only two countries (Italy and Spain) not participating.

This idea has been revived recently because of various events, such as

• the Euro with 17 EU member-states and three more in ERM II on track to joining. All but two states (Denmark, United Kingdom) have agreed by treaty to join but at least one of those treaty signatories (Sweden) has made no further steps to do so.
• the Schengen area Treaty leading to a common border for many EU states (it currently excludes Bulgaria, Cyprus, Ireland, Romania and the United Kingdom) but which includes four non-EU members - Norway, Switzerland, Iceland and Liechtenstein. It is often asserted that Ireland only reluctantly agreed to stay out of the treaty to avoid creating a physical border between the Republic and Northern Ireland because the UK had refused to sign.
• other initiatives limited to some states, such as the European Defence initiative and Prüm Convention.
• the enlargement of the European Union to 27 member-states, with the prospect of accepting Croatia in 2013 and in the forthcoming years other candidates (Turkey, Montenegro, Macedonia, Serbia and Iceland among others) where new members initially don't join the Schengen area and the Eurozone for some time.
• the European Convention that led to the European Constitution that was signed in 2004 by the 25 Heads of State, but was not ratified by all national parliaments or assemblies and so failed. Later most of its provisions were adopted trough the Treaty of Lisbon that included additional opt-outs for some states.
• differences of view between EU members on some foreign diplomatic and military issues.

The Economist in a 2004 article compared the variances of Europe to a lake that has many deep parts (areas in which countries are similar) and many shallow parts (areas in which countries have major differences).

Currently in the EU there are the following cases of non-uniform application of the European Union law: