There is ongoing discussion about the extent to which the European Union (EU) has already turned from a confederation into a federation over the course of decades, and more importantly, to what degree it should continue to evolve into a federalist direction. As of January 2024, the EU has no formal plans to become a federation.

The Treaty on European Union, commonly known as the Maastricht Treaty, is the foundation treaty of the European Union (EU). Concluded in 1992 between the then-twelve member states of the European Communities, it announced "a new stage in the process of European integration" chiefly in provisions for a shared European citizenship, for the eventual introduction of a single currency, and for common foreign and security policies, and a number of changes to the European institutions and their decision taking procedures, not least a strengthening of the powers of the European Parliament and more majority voting on the Council of Ministers. Although these were seen by many to presage a "federal Europe", key areas remained inter-governmental with national governments collectively taking key decisions. This constitutional debate continued through the negotiation of subsequent treaties, culminating in the 2007 Treaty of Lisbon.