Danish opt-outs and opt-ins
The Danish and British Governments have opt-in arrangements for home and justice affairs allowing these countries to decide whether they want to participate in joint EU legislation.
The Danish opt-outs from the Treaty of Nice have been upheld under the revised EU constitution in the Lisbon Treaty.
The Danish derogations relate to defence, citizenship, the euro and home and justice affairs. The vast majority of members in the Danish Parliament want to abolish the derogations. However, it must be decided by referendum.
A Danish referendum in 2000 went wrong for the government so that Denmark still has its national currency.