Danish opt-outs from the European Union

One or more referendums on abolishing one or more the opt-outs were announced by Prime Minister Anders Fogh Rasmussen in his speech on 22 November 2007 after he won the 2007 parliamentary election.[4] It was not announced whether the referendum would only offer a full repeal of all opt-outs, or a case-by-case choice, and no date was announced, except that it would be before the 2011 Danish parliamentary election.[5] The V/K (Liberal-Conservative) government had been planning to hold a referendum on abolishing the opt-outs (or at least the euro opt-out) since at least 2004, following a favourable change in public opinion, but the discussions and controversy regarding the Treaty establishing a Constitution for Europe and the Treaty of Lisbon had delayed this.[6]

The referendum was originally expected to be held in the autumn of 2008[7][8][9][10] but following Ireland's rejection of the Treaty of Lisbon, Fogh Rasmussen stated that this would not happen.[11] In early 2009, it was announced that Fogh Rasmussen expected to hold a referendum on Denmark joining the Eurozone in 2010, as he believed it was possible to meet the demands of the Euro-sceptic Socialist People's Party.[12]

Following the appointment of Anders Fogh Rasmussen as Secretary General of NATO in 2009, his successor, Lars Løkke Rasmussen, announced that the opt-outs would be put to a referendum "when the time is right", which was seen as an indication that he did not necessarily intend to proceed with a referendum.[13]

A month later, in May 2009, Løkke Rasmussen stated that he hoped at least a referendum on the common currency would take place before the parliamentary elections in 2011 so that Denmark could become "a full member of the European Union",[14][15] and to give him a popular mandate in the negotiations over the Competitiveness Pact in the Summer of that year.[16] The Prime Minister's suggestion was criticised by Jens Ladefoged Mortensen, a political scientist, who claimed that the time for a referendum was ill-chosen, pointing out that Denmark was set to hold general elections later that year.[17]

In November 2009 the leaders of the three largest opposition parties Helle Thorning-Schmidt, Villy Søvndal and Margrethe Vestager suggested that a referendum on abolishing the opt-outs concerning the Common Security and Defence Policy and the Justice and Home Affairs be held on 23 March 2010.[18]

Ultimately, no referendum was held and Løkke Rasmussen's coalition lost the election in the autumn of 2011.

After the victory of the left-wing coalition under Thorning-Schmidt in the September 2011 elections, the new government announced that it planned to hold referendums on abolishing the defence opt-out and on either abolishing the justice opt-out or modifying it to a flexible opt-in like that of the United Kingdom and Republic of Ireland to allow Denmark to participate in measures which it chooses.[19][20] However, in June 2012 Thorning-Schmidt announced that she didn't anticipate holding a referendum before a certain amount of stability and order returned to the situation in Europe, possibly not before the end of the government's term, citing the "anxiety and uncertainty" surrounding the European project at the time.[21][22]

In August 2013, Lars Løkke Rasmussen, the leader of the opposition Venstre party proposed that a referendum on the opt-outs from EU defence and justice co-operation, as well as on the Unified Patent Court, leaving opt-outs from European citizenship and the euro, be held on the same date as the 2014 European election.[23] The proposal was rejected by the Minister for European affairs, Nick Hækkerup, who argued that the timing was not right.[24]

In October 2014 Thorning-Schmidt announced plans to hold a referendum on converting the inflexible opt-out on home and justice matters into a flexible opt-out following the next Danish general election due by September 2015, due to concerns that the opt-out would force Denmark to leave Europol.[25][26] Several parties, including the two largest in parliament, the Social Democrats and Liberals, reached an agreement in December 2014 to hold the referendum following the upcoming election, but before the end of the first quarter of 2016, if they secured enough seats in the election.[27] This was supplemented by an agreement in March 2015 amongst the parties that if the referendum is approved, Denmark would join 22 EU regulations it is currently not able to participate in, including the Rome Regulation.[28][29] To join additional Regulations, the agreement requires either consensus amounts the parties to the agreement, or that the proposal is made public as part of the party's platform prior to a subsequent election.[30]

Following the election in June 2015, Venstre formed government with Lars Løkke Rasmussen again becoming Prime Minister. He committed to holding the referendum on converting the justice opt-out into an opt-in by Christmas 2015.[31][32] On 21 August 2015, the Danish government announced that the referendum would be held on 3 December 2015.[1] The government has also said it is planning on holding a referendum on abolishing its opt-out from the EU defence policy following the justice opt-out referendum.[33] Danes rejected the proposal by a margin of 53.1% to 46.9%. In May 2019 Rasmussen again proposed a referendum on abolishing its defence opt-out during the following parliamentary term, though his party lost the general election the following month.[34]

Following the 2022 Russian invasion of Ukraine, Denmark held a referendum on abolishing its defence opt-out. The referendum took place on 1 June 2022, ending with the yes side winning by two thirds of the vote. Following the referendum Denmark formally notified the EU of its renunciation of its opt-out on defence matters, effective from 1 July.[35][36] Frederiksen stated that despite the approval of the eliminating the defence opt-out, she did not plan to hold referendums on the other remaining opt-outs.[37]