Brexit withdrawal agreement in the context of "Withdrawal from the EU"

The European single market, also known as the European internal market or the European common market, is the single market comprising mainly the 27 member states of the European Union (EU). With certain exceptions, it also comprises Iceland, Liechtenstein, Norway (through the Agreement on the European Economic Area), and Switzerland (through sectoral treaties). The single market seeks to guarantee the free movement of goods, capital, services, and people, known collectively as the four freedoms of the European Union. This is achieved through common rules and standards that all participating states are legally committed to follow.

Any potential EU accession candidates are required to make association agreements with the EU during the negotiation, which must be implemented prior to accession. In addition, through three individual agreements on a Deep and Comprehensive Free Trade Area (DCFTA) with the EU, Georgia, Moldova, and Ukraine have also been granted limited access to the single market in selected sectors. Turkey has access to the free movement of some goods via its membership in the European Union–Turkey Customs Union. The United Kingdom left the European single market on 31 December 2020. An agreement was reached between the UK Government and European Commission to align Northern Ireland on rules for goods with the European single market, to maintain an open border on the island of Ireland.

The impact of Brexit on the Irish border and its adjacent polities involves changes in trade, customs, immigration checks, local economies, services, recognition of qualifications, medical cooperation, and other matters, as it is the only land border between the United Kingdom and the European Union.

After the UK Parliament voted to leave the European Union, all parties said that they want to avoid a hard border in Ireland, due particularly to the border's historically sensitive nature. Border issues were one of three areas of focused negotiation in the Withdrawal Agreement. Following the United Kingdom's exit from the European Union on 31 January 2020, this border is also the frontier between the EU and an external country.

Article 50 of the Treaty on European Union (TEU) provides for the possibility of an EU member state leaving the European Union "in accordance with its own constitutional requirements".

Currently, the United Kingdom is the only state to have withdrawn from membership of the European Union. The process to do so began when the UK Government triggered Article 50 to begin the UK's withdrawal from the EU on 29 March 2017 following a June 2016 referendum, and the withdrawal was scheduled in law to occur on 29 March 2019. Subsequently, the UK sought, and was granted, a number of Article 50 extensions until 31 January 2020. On 23 January 2020, the withdrawal agreement was ratified by the Parliament of the United Kingdom, and on 29 January 2020 by the European Parliament. The UK left the EU on 31 January 2020 at 23:00 GMT, ending 47 years of membership.

The Republic of Ireland–United Kingdom border, sometimes referred to as the Irish border or British–Irish border, runs for 499 km (310 mi) from Lough Foyle in the north-west of Ireland to Carlingford Lough in the north-east, separating the Republic of Ireland from Northern Ireland.

Border markings are inconspicuous, in common with many inter-state borders in the European Union. As the two states share a Common Travel Area and (as of 2021) Northern Ireland (the only exception within the UK and only in some respects) and the Republic of Ireland are participants in the European Single Market, the border is essentially an open one, allowing free passage of people since 1923 and of goods since 1993. There are circa 270 public roads that cross the border. Following the United Kingdom's exit from the European Union, this border is also the frontier between the EU and a non-member country. The Brexit withdrawal agreement commits all involved parties to maintaining an open border in Ireland, so that (in many respects) the trade frontier is the Irish Sea between the two islands. This de facto division of the United Kingdom is described, especially by Unionists, as "the Irish Sea border".