Maastricht Treaty

The treaty transformed existing European cooperation into the European Union while preserving the European Communities as its institutional core. It organized cooperation through a three-pillar structure: the European Communities, a common foreign and security policy, and justice and home affairs.

The first pillar used supranational institutions and Community law, while the other two initially relied more heavily on intergovernmental decision-making. This distinction shaped the balance between the European Commission, the Council of the European Union, the European Parliament, and national governments. The treaty also introduced the principle of subsidiarity, under which the Union should act only when objectives could be achieved more effectively at European level than by member states individually.

The Maastricht Treaty established the legal and economic route toward a single currency. It set convergence criteria covering price stability, public finances, exchange-rate stability, and long-term interest rates; these conditions were intended to limit economic divergence before countries adopted the euro.

The treaty divided economic and monetary union into stages. It strengthened coordination of national economic policies, created the institutional framework for the European System of Central Banks, and committed participating states to a common monetary policy. The euro was introduced for accounting and financial purposes in 1999 and entered circulation as notes and coins in 2002. Not every member state joined: the United Kingdom and Denmark secured treaty-based opt-outs, while other states remained outside after not meeting, or not choosing to meet, the conditions for participation.

Union citizenship gave nationals of member states additional rights that complemented national citizenship. These included the right to move and reside within the Union subject to treaty conditions, vote and stand in European Parliament and municipal elections in the member state of residence, receive consular protection from another member state where their own country was unrepresented, and petition the European Parliament or appeal to the European Ombudsman.

The treaty also increased the European Parliament’s role through the cooperation and assent procedures, although Parliament did not yet possess the extensive legislative powers later associated with the ordinary legislative procedure. Its ratification exposed a democratic and constitutional tension: national electorates were being asked to approve deeper integration even as decision-making shifted toward European institutions. In Denmark, an initial referendum rejected the treaty in June 1992; a second referendum approved it in May 1993 after negotiated opt-outs.¹

The treaty’s title reflected a deliberate political change: the European Union was created as an overarching framework, but it was not itself a single legal personality in the modern sense. That distinction remained significant until the Treaty of Lisbon abolished the pillar structure and gave the Union a unified legal personality.

Several provisions had effects beyond the headline creation of the euro. The treaty formalized cooperation on education, vocational training, culture, public health, consumer protection, and trans-European networks, while generally limiting the Union’s power to harmonize national laws in these fields. It also created the Committee of the Regions and strengthened the idea that European decisions should be taken as openly and closely as possible to citizens. The treaty therefore combined market integration, monetary discipline, citizenship rights, and a cautious expansion of political cooperation rather than functioning solely as a currency agreement.

Economic and monetary union

A framework for coordinating member states’ economic policies and, for participating countries, sharing a single currency and common monetary policy.

Convergence criteria

Economic conditions concerning inflation, public finances, exchange rates, and interest rates used to assess eligibility for adopting the euro.

Subsidiarity

The principle that the Union should act at European level only when an objective cannot be sufficiently achieved by member states acting alone.

Union citizenship

A status held by every national of an EU member state, providing additional rights alongside national citizenship.