Federalisation of the European Union in the context of "Sui generis"

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 (with less precision) for common foreign and security policies, and a number of changes to the European institutions and their decision-making 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 (see below), culminating in the 2007 Treaty of Lisbon.

In the wake of the Eurozone debt crisis unfolding from 2009, the most enduring reference to the Maastricht Treaty has been to the rules of compliance – the "Maastricht criteria" – for the currency union.

Volt Europa (known mononymously as Volt) is a transnational pro-European and federalist European political movement. It operates as a pan-European umbrella for subsidiary parties sharing the same name and branding.

Volt aligns its political positions across Europe, presenting a common, pan-European manifesto. In the 2019 European Parliament elections, Volt ran in eight member states with a shared platform, emphasising solutions to supranational challenges, such as climate change, defense, energy policy, migration, economic inequality, terrorism, welfare, and the technological evolution of the labor market. The party advocates for a stronger, more integrated European Union, with the long-term goal of creating a federal Europe. Additionally, Volt endorses the formation of a European army, joint European debt and taxes, nuclear energy including the construction of new nuclear power plants, and stronger economic solidarity between the EU member states.

Pan-European identity is the sense of personal identification with Europe, in a cultural or political sense. The concept is discussed in the context of European integration, historically in connection with hypothetical proposals, but since the formation of the European Union (EU) in the 1990s increasingly with regard to the project of ever-increasing federalisation of the EU. The model of a "pan-European" union is the Carolingian Empire, which first defined "Europe" as a cultural entity as the areas ruled by the Roman Catholic Church, later known as "Medieval Western Christendom" (which extended its scope further eastwards to the shores of the Baltic Sea during the course of the Middle Ages). The original proposal for a Paneuropean Union was made in 1922 by Count Richard von Coudenhove-Kalergi, who defined the term "pan-European" as referring to this historical sense of the western and central parts of continental Europe encompassing the cultures that evolved from medieval Western Christendom (i.e. Catholic and Protestant Europe, with the exception of the British Isles) instead of the modern geographic definition of the continent of Europe. Coudenhove-Kalergi saw the pan-European state as a future "fifth great power", in explicit opposition to the Soviet Union, "Asia", Great Britain and the United States (as such explicitly excluding both the British Isles and the areas that were influenced by Byzantine Christendom, which are usually considered a part of geographical Europe, from his notion of "pan-European").

After 1948, an accelerating process of European integration culminated in the formation of the EU in 1993. In the period from 1995–2020, the EU has been enlarged from 12 to 27 member states, far beyond the area originally envisaged for the "pan-European" state by Coudenhove-Kalergi (with the exception of Switzerland), its member states accounting for a population of some 447 million, or three-fifths of the population of the entire continent. In the 1990s to 2000s, there was an active movement towards further consolidation of the European Union, with the introduction of symbols and institutions usually reserved for sovereign states, such ascitizenship, a common currency (used by 20 out of 27 members), a flag, an anthem and a motto (In Varietate Concordia, "United in Diversity"). An attempt to introduce a European Constitution was made in 2004, but it failed to be ratified; instead, the Treaty of Lisbon was signed in 2007 in order to salvage some of the reforms that had been envisaged in the constitution.