On June 1, voters in Denmark will take part in a referendum on whether to end the country’s opt-out from EU defence policy, which prohibits Denmark from participating in EU defence matters. This means that when the EU deploys personnel under its common security and defence policy, Denmark participates in civilian but not military operations.
This was one of four arrangements secured when Danes voted “no” to the 1992 Maastricht treaty to establish the EU. Along with defence policy, Denmark opted out of the euro, justice and home affairs. The European Council also agreed to a Danish declaration that EU citizenship could only ever complement national citizenship – not replace it. These four arrangements for Denmark persuaded voters to support the Maastricht treaty in a second referendum in 1993.
The citizenship arrangement later became the norm for all member states through the 1997 Amsterdam treaty, which ratified that EU citizenship is supplementary to citizenship of a member state and cannot replace it.
