1992 Danish Maastricht Treaty referendum

A referendum on the Maastricht Treaty for the founding of the European Union was held in Denmark on 2 June 1992. The treaty was rejected by 50.7% of voters with a turnout of 83.1%. This meant a serious hurdle on the way in the process of further European integration, which nevertheless did continue because all twelve member states did want to ratify.

The result of the referendum, along with the "petit oui" in the French Maastricht referendum did however signal a new stadium in European integration, away from the "permissive consensus" which had existed in most of the memberstates until then. Integration mainly did occur through strategic negotiations between the Member States or through functional adaptation of the system. Now the question of democracy as an explanatory variable had to be taken into consideration. This was expressed by Pascal Lamy, chef de cabinet for Jacques Delors, the president of the European Commission, who rafter the Danish referendum remarked that, "Europe was built in a Saint-Simonian [i.e., technocratic] way from the beginning, this was Monnet's approach: The people weren't ready to agree to integration, so you had to get on without telling them too much about what was happening. Now Saint-Simonianism is finished. It can't work when you have to face democratic opinion."

From this point forward issues relating to European integration were subject to deeper discussions across much of Europe. Some years later overt euroscepticism gained prominence. Besides Denmark only France and Ireland held referendums on the Maastricht Treaty ratification.

As the Maastricht Treaty could only come into effect if all members of the European Union ratified it, negotiations were set up in the months following the referendum. This resulted in the Edingburgh Agreement, providing Denmark with four exceptions or opt-outs from close co-operation in certain policy fields which eventually led to Denmark ratifying the Maastricht Treaty in a 1993 referendum.

Edinburgh agreement: opt-outs
The opt-outs are outlined in the Edinburgh Agreement and concern the EMU, the Common Security and Defence Policy (CSDP), Justice and Home Affairs (JHA) and the citizenship of the European Union. With these opt-outs the Danish people accepted the treaty in a second referendum held in 1993.

The EMU opt-out meant Denmark was not obliged to participate in the third phase of the European Exchange Rate Mechanism, i.e. to replace the Danish krone with the euro. The abolition of the euro opt-out was put to a referendum in 2000 and was rejected. The CSDP opt-out originally meant Denmark would not be obliged to join the Western European Union (which originally handled the defence tasks of the EU). Now it means that Denmark does not participate in the European Union's foreign policy where defence is concerned. Hence it does not take part in decisions, does not act in that area and does not contribute troops to missions conducted under the auspices of the European Union. The JHA opt-out exempts Denmark from certain areas of home affairs.

Significant parts of these areas were transferred from the third European Union pillar to the first under the Amsterdam Treaty; Denmark's opt-outs from these areas were kept valid through additional protocols. Acts made under those powers are not binding on Denmark except for those relating to Schengen, which are instead conducted on an intergovernmental basis with Denmark. The citizenship opt-out stated that European citizenship did not replace national citizenship; this opt-out was rendered meaningless when the Amsterdam Treaty adopted the same wording for all members. Under the Treaty of Lisbon, Denmark can change its opt-out from a complete opt-out to the case-by-case opt-in version that applies to Ireland whenever they wish.

Aftermath
The June Movement, a Danish eurosceptic party and political organization was founded immediately after the referendum, and takes its name from the event.