Brexit (/ˈbrɛksɪt, ˈbrɛɡzɪt/;^[4] a portmanteau of "British" and "exit") is the scheduled withdrawal of the United Kingdom (UK) from the European Union (EU). Following a June 2016 referendum, in which 51.9% voted to leave, the UK government formally announced the country's withdrawal in March 2017, starting a two-year process that was due to conclude with the UK withdrawing on 29 March 2019. As the UK parliament thrice voted against the negotiated withdrawal agreement, that deadline has been extended twice, and is currently 31 October 2019.^[5][6] An Act of Parliament requires the government to seek a third extension if no agreement is reached before 19 October.

Withdrawal is advocated by Eurosceptics and opposed by pro-Europeanists, both of whom span the political spectrum. The UK joined the European Communities (EC) in 1973, with continued membership endorsed in a 1975 referendum. In the 1970s and 1980s, withdrawal from the EC was advocated mainly by the political left, e.g. in the Labour Party's 1983 election manifesto. From the 1990s, the eurosceptic wing of the Conservative Party grew, and led a rebellion over ratification of the 1992 Maastricht Treaty that established the EU. In parallel with the UK Independence Party (UKIP), and the cross-party People's Pledge campaign, it pressured Conservative Prime Minister David Cameron to hold a referendum on continued EU membership. Cameron, who had campaigned to remain, resigned after the result and was succeeded by Theresa May.

On 29 March 2017, the UK government invoked Article 50 of the Treaty on European Union, formally starting the withdrawal. May called a snap general election in June 2017, which resulted in a Conservative minority government supported by the Democratic Unionist Party. UK–EU withdrawal negotiations began later that month. The UK negotiated to leave the EU customs union and single market. This resulted in the November 2018 withdrawal agreement, but the UK parliament voted against ratifying it three times. The Labour Party wanted any agreement to maintain a customs union, while many Conservatives opposed the agreement's financial settlement on the UK's share of EU financial obligations, as well as the "Irish backstop" designed to prevent border controls in Ireland. The Liberal Democrats, Scottish National Party and others seek to reverse Brexit through a second referendum. The EU has declined a re-negotiation that omits the backstop. In March 2019, the UK parliament voted for May to ask the EU to delay Brexit until October. Having failed to pass her agreement, May resigned as Prime Minister in July and was succeeded by Boris Johnson. He sought to replace parts of the agreement and vowed to leave the EU by the new deadline, with or without an agreement.

Many effects of Brexit depend on how closely the UK will be tied to the EU, or whether it withdraws before terms are agreed – referred to as a no-deal Brexit. The broad consensus among economists is that Brexit will likely reduce the UK's real per capita income in the medium term and long term, and that the referendum itself damaged the economy.^[1] Brexit is likely to reduce immigration from European Economic Area (EEA) countries to the UK, and poses challenges for UK higher education, academic research and security. Following Brexit, EU law and the EU Court of Justice will no longer have supremacy over UK laws or its Supreme Court, except to an extent agreed upon in a withdrawal agreement. The European Union (Withdrawal) Act 2018 retains relevant EU law as domestic law, which the UK could then amend or repeal.

In the wake of the referendum of 23 June 2016, many new pieces of Brexit-related jargon have entered popular use.^[20][21]

The "Inner Six" European countries signed the Treaty of Paris in 1951, establishing the European Coal and Steel Community (ECSC). The 1955 Messina Conference deemed that the ECSC was a success, and resolved to extend the concept further, thereby leading to the 1957 Treaties of Rome establishing the European Economic Community (EEC) and the European Atomic Energy Community (Euratom). In 1967, these became known as the European Communities (EC). The UK attempted to join in 1963 and 1967, but these applications were vetoed by the President of France, Charles de Gaulle.^[75]

Some time after de Gaulle resigned as president of France in 1969, the UK successfully applied for EC membership, and the Conservative prime minister Edward Heath signed the Treaty of Accession in 1972.^[76] Parliament passed the European Communities Act later that year^[77] and the UK joined Denmark and Ireland in becoming a member of the EC on 1 January 1973.^[78]

The opposition Labour Party won the February 1974 general election without a majority and then contested the subsequent October 1974 general election with a commitment to renegotiate Britain's terms of membership of the EC, believing them to be unfavourable, and then hold a referendum on whether to remain in the EC on the new terms.^[79] Labour again won the election (this time with a small majority), and in 1975 the UK held its first ever national referendum, asking whether the UK should remain in the EC. Despite significant division within the ruling Labour Party,^[80] all major political parties and the mainstream press supported continuing membership of the EC. On 5 June 1975, 67.2 percent of the electorate and all but two^[81] UK counties and regions voted to stay in;^[82] support for the UK to leave the EC in 1975 appears unrelated to the support for Leave in the 2016 referendum.^[83]

The Labour Party campaigned in the 1983 general election on a commitment to withdraw from the EC without a referendum,^[84] although after a heavy defeat Labour changed its policy.^[84] In 1985, the second Margaret Thatcher government ratified the Single European Act—the first major revision to the Treaty of Rome—without a referendum.

In October 1990, under pressure from senior ministers and despite Thatcher's deep reservations, the UK joined the European Exchange Rate Mechanism (ERM), with the pound sterling pegged to the deutschmark. Thatcher resigned as Prime Minister the following month, amid Conservative Party divisions arising partly from her increasingly Eurosceptic views. The UK and Italy were forced to withdraw from the ERM in September 1992, after the pound sterling and the lira came under pressure from currency speculation ("Black Wednesday").^[85]

Under the Maastricht Treaty, the EC became the EU on 1 November 1993,^[86] reflecting the evolution of the organisation from an economic union into a political union.^[87] Denmark, France, and Ireland held referendums to ratify the Maastricht Treaty. In accordance with British constitutional convention, specifically that of parliamentary sovereignty, ratification in the UK was not subject to approval by referendum. Despite this, the British constitutional historian Vernon Bogdanor wrote at the time that there was "a clear constitutional rationale for requiring a referendum" because although MPs are entrusted with legislative power by the electorate, they are not given authority to transfer that power (the UK's previous three referendums all concerned the transfer of parliamentary powers). Further, as the ratification of the treaty was in the manifestos of the three major political parties, voters opposed to ratification had no way to express that opposition. For Bogdanor, while the ratification of the treaty by the House of Commons might be legal, it would not be legitimate—which requires popular consent. The way in which the treaty was ratified, he judged, was "likely to have fundamental consequences both for British politics and for Britain's relationship with the [EC]."^[88][89] This perceived democratic deficit directly led to the formation of the Referendum Party and the UK Independence Party.

Thatcher, who had supported the common market and the Single European Act, in the Bruges speech of 1988 warned against "a European super-state exercising a new dominance from Brussels". She influenced Daniel Hannan, who in 1990 founded the Oxford Campaign for Independent Britain; "With hindsight, some see this as the start of the campaign for Brexit", Financial Times later wrote.^[90] In 1994, Sir James Goldsmith formed the Referendum Party to contest the 1997 general election on a platform of providing a referendum on the nature of the UK's relationship with the rest of the EU.^[91][92] The party fielded candidates in 547 constituencies at that election, and won 810,860 votes—2.6 per cent of the total votes cast^[93]—but failed to win a parliamentary seat due to the vote being spread across the country. The Referendum Party disbanded after Goldsmith's death in 1997.

The UK Independence Party (UKIP), a Eurosceptic political party, was formed in 1993. It achieved third place in the UK during the 2004 European elections, second place in the 2009 European elections and first place in the 2014 European elections, with 27.5 per cent of the total vote. This was the first time since the 1910 general election that any party other than Labour or the Conservatives had taken the largest share of the vote in a nationwide election.^[94] UKIP's electoral success in the 2014 European election is documented as the strongest correlate of the support for the Leave campaign in the 2016 referendum.^[95]

UKIP won two by-elections (triggered by defecting Conservative MPs) in 2014; in the 2015 general election, the party took 12.6 percent of the total vote and held one of the two seats won in 2014.^[96]

Both pro- and anti-EU views have had majority support at different times since 1977.^[97] In the EC membership referendum of 1975, two-thirds of British voters favoured continued EC membership. There is Euroscepticism both on the left and right of British politics.^{[98][99][100]}

According to a statistical analysis published in April 2016 by Professor John Curtice of Strathclyde University, surveys showed an increase in Euroscepticism (defined as a wish to sever or reduce the powers of the EU) from 38% in 1993 to 65% in 2015. Euroscepticism should, however, not be confused with the wish to leave the EU: the BSA survey for the period July–November 2015 showed that 60 per cent backed the option to continue as an EU member and 30 percent backed the option to withdraw.^[101]

In 2012, Prime Minister David Cameron initially rejected calls for a referendum on the UK's EU membership,^[102] but then suggested the possibility of a future referendum to endorse his proposed renegotiation of Britain's relationship with the rest of the EU.^[103] According to the BBC, "The prime minister acknowledged the need to ensure the UK's [renegotiated] position within the [EU] had 'the full-hearted support of the British people' but they needed to show 'tactical and strategic patience'."^[104] On 23 January 2013, under pressure from many of his MPs and from the rise of UKIP, Cameron announced that a Conservative government would hold an in-or-out referendum on EU membership before the end of 2017, on a renegotiated package, if elected in the 7 May 2015 general election.^[105] This was included in the Conservative Party manifesto for the election.^[106][107]

The Conservative Party won the election with a majority. Soon afterwards, the European Union Referendum Act 2015 was introduced into Parliament to enable the referendum. Cameron favoured remaining in a reformed EU, and sought to renegotiate on four key points: protection of the single market for non-eurozone countries, reduction of "red tape", exempting Britain from "ever-closer union", and restricting immigration from the rest of the EU.^[108]

In December 2015, opinion polls showed a clear majority in favour of remaining in the EU; they also showed support would drop if Cameron did not negotiate adequate safeguards for non-eurozone member states, and restrictions on benefits for non-British EU citizens.^[109]

The outcome of the renegotiations was announced in February 2016. Some limits to in-work benefits for new EU immigrants were agreed, but before they could be applied, a member state such as the UK would have to get permission from the European Commission and then from the European Council, which is composed of the heads of government of every member state.^[110]

In a speech to the House of Commons on 22 February 2016, Cameron announced a referendum date of 23 June 2016, and commented on the renegotiation settlement.^[111] He spoke of an intention to trigger the Article 50 process immediately following a Leave vote and of the "two-year time period to negotiate the arrangements for exit."^[112]

After the original wording for the referendum question was challenged,^[113] the government agreed to change the official referendum question to "Should the United Kingdom remain a member of the European Union or leave the European Union?"

The official campaign group for leaving the EU was Vote Leave^[114] after a contest for the designation with Leave.EU.^[115][116] Vote Leave was later found to have exceeded its allowed spending limit during the campaign.^[117]

The official campaign to stay in the EU, chaired by Stuart Rose, was known as Britain Stronger in Europe, or informally as 'Remain'. Other campaigns supporting remaining in the EU included Conservatives In,^[118] Labour in for Britain,^[119] #INtogether (Liberal Democrats),^[120] Greens for a Better Europe,^[121] Scientists for EU,^[122] Environmentalists for Europe,^[123] Universities for Europe^[124] and Another Europe is Possible.^[125]

The result was announced on the morning of 24 June: 51.89 percent voted in favour of leaving the EU, and 48.11 percent voted in favour of remaining a member of the EU.^[126][127] Comprehensive results are available from the UK Electoral Commission Referendum Results site. A petition calling for a second referendum attracted more than four million signatures,^[128][129] but was rejected by the government on 9 July.^[130]

According to researchers based at the University of Warwick, areas with "deprivation in terms of education, income and employment were more likely to vote Leave". The Leave vote tended to be greater in areas which had lower incomes and high unemployment, a strong tradition of manufacturing employment, and in which the population had fewer qualifications.^[131] It also tended to be greater where there was a large flow of Eastern European migrants (mainly low-skilled workers) into areas with a large share of native low-skilled workers.^[131] Those in lower social grades (especially the 'working class') were more likely to vote Leave, while those in higher social grades (especially the 'upper middle class') more likely to vote Remain.^[132]

According to Thomas Sampson, an economist at the London School of Economics, "Older and less-educated voters were more likely to vote 'leave' [...] A majority of white voters wanted to leave, but only 33 per cent of Asian voters and 27 per cent of black voters chose leave. There was no gender split in the vote [...] Leaving the European Union received support from across the political spectrum [...] Voting to leave the European Union was strongly associated with holding socially conservative political beliefs, opposing cosmopolitanism, and thinking life in Britain is getting worse".^[8] Econometric studies show that "education and, to a lesser extent, age were the strongest demographic predictors of voting behaviour". Support for leaving was linked with "poor economic outcomes at the individual or area level" and with "self-reported opposition to immigration, but not with exposure to immigration".^[8]

Opinion polls found that Leave voters believed leaving the EU was "more likely to bring about a better immigration system, improved border controls, a fairer welfare system, better quality of life, and the ability to control our own laws", while Remain voters believed EU membership "would be better for the economy, international investment, and the UK's influence in the world". Polls found that the main reasons people voted Leave were "the principle that decisions about the UK should be taken in the UK", and that leaving "offered the best chance for the UK to regain control over immigration and its own borders". The main reason people voted Remain was that "the risks of voting to leave the EU looked too great when it came to things like the economy, jobs and prices".^[133]

After the result was declared, Cameron announced that he would resign by October.^[134] He stood down on 13 July 2016, with Theresa May becoming Prime Minister after a leadership contest. George Osborne was replaced as Chancellor of the Exchequer by Philip Hammond, former Mayor of London Boris Johnson was appointed Secretary of State for Foreign and Commonwealth Affairs, and David Davis became Secretary of State for Exiting the European Union. Labour leader Jeremy Corbyn lost a vote of confidence among his parliamentary party, and an unsuccessful challenge of his leadership was launched. On 4 July, Nigel Farage announced his resignation as leader of UKIP.^[135]

Irregularities have been alleged in the conduct of the referendum campaign.

On 11 May 2018, the UK Electoral Commission found against Leave.EU, which ran a separate campaign to the official pro-Brexit group Vote Leave, following its investigations into alleged irregularities during the referendum campaign.^[136][137] Leave.EU's co-founder Arron Banks has stated that he rejects the outcome of the investigation and will be challenging it in court.^[138]

In July 2018, the UK Electoral Commission found Vote Leave to have broken electoral law, spending over its limit.^[139] Also, the House of Commons Culture, Media and Sport Select Committee released an interim report on Disinformation and ‘fake news’, stating that the largest donor in the Brexit campaign, Arron Banks, had "failed to satisfy" the Committee that his donations came from UK sources, and may have been financed by the Russian government.^[140][141]

There has been litigation to explore the constitutional footings on which Brexit stands after R (Miller) v Secretary of State for Exiting the European Union (simply known as the "Miller case") and the 2017 Notification Act:

Below is the timeline of major events concerning Brexit.^[149]

Withdrawal from the European Union is governed by Article 50 of the Treaty on European Union, which was introduced by the Treaty of Lisbon at the insistence of the United Kingdom. Under the Article 50 invocation procedure, a member notifies the European Council, whereupon the EU is required to "negotiate and conclude an agreement with [the leaving] State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the [European] Union". The negotiation period is limited to two years unless extended, after which the treaties cease to apply.^[167] There was a discussion on whether parallel negotiation of withdrawal terms and future relationships under Article 50 are appropriate (Chancellor Merkel's initial view) or whether Britain did not have the right to negotiate future trade with the 27 remaining countries of the EU (also known as the EU27), as this power is arguably reserved to the EU as long as the UK is a member (the view of a European Commission lawyer).^[168]

Although the 2015 Referendum Act did not expressly require Article 50 to be invoked,^[169] the UK government stated that it would expect a leave vote to be followed by withdrawal.^[170][171] Following the referendum result, Cameron resigned and said that it would be for the incoming Prime Minister to invoke Article 50.^[172][173]

The UK Supreme Court ruled in the Miller case in January 2017 that the government needed parliamentary approval to trigger Article 50.^[174][175] Subsequently, the House of Commons overwhelmingly voted, on 1 February 2017, for a government bill authorising the prime minister to notify an intention to leave under Article 50,^[176] and the bill passed into law as the European Union (Notification of Withdrawal) Act 2017. Theresa May then signed a letter invoking Article 50 on 28 March 2017, which was delivered on 29 March by Tim Barrow, the UK's ambassador to the EU, to European Council President Donald Tusk.^{[177][178][179]}

It had been argued that the Article 50 withdrawal process could be halted unilaterally by the British government,^[180] an opinion with which the author of Article 50 itself, Lord Kerr, expressed agreement.^[181] The European Parliament's Brexit committee said that unilateral revocation, regardless of its legality, poses a substantial moral hazard, with an EU member state potentially able to abuse it to blackmail the Union.^[182]

The reversibility of notifications under Article 50 was subject to litigation, which a cross-party group of Scottish politicians and the Good Law Project referred to the Court of Justice of the EU (ECJ).^[183] The UK government sought to block this referral, ultimately in the UK Supreme Court, but it was unsuccessful in this attempt.^[184] On 10 December 2018, the ECJ ruled that a country could unilaterally cancel its withdrawal from the EU, by simple notice, provided that it did so prior to actual departure, unconditionally and in good faith.^[185] However, the Government's immediate response was that it had no intention of exercising that right.^[185]

Both parties to the withdrawal negotiation are bound by Article 50 (3) of the Treaty, which states explicitly that the EU treaties will cease to apply "from the date of entry into force of the withdrawal agreement or, failing that, two years after" the withdrawal notification unless the EU Council and the UK agree to extend the two-year period.^[186]

The European Union (Withdrawal) Act 2018 (as amended by a UK Statutory Instrument on 11 April 2019), in section 20 (1), defines 'exit day' as 11:00 p.m. on 31 October 2019.^[187] Originally, 'exit day' was defined as 11:00 p.m. on 29 March 2019 GMT (UTC+0).^{[188][189][186][190][191]}

The European Commission said that it would not start any negotiation before the UK formally invoked Article 50.^[192] In October 2016, European Commission President Jean-Claude Juncker said the EU should not negotiate in such a way that Britain would have to hold a second referendum.^[193] On 28 June 2016, Chancellor Merkel, and on the following day European Council President Tusk, stated that the UK could remain in the European Single Market (ESM) only if the UK accepted its four freedoms of movement: for goods, capital, services, and labour.^[194] In October, Prime Minister May emphasised that ending the jurisdiction of EU law and free movement from Europe were the UK's priorities, along with British and EU companies having maximum freedom to trade in the UK and the ESM.^[195][196]

In November 2016, May proposed that Britain and the other EU member states mutually guarantee the residency rights of the 3.3 million non-British EU citizens in the UK and those of the 1.2 million British citizens living in the rest of the EU, in order to exclude their fates being bargained during Brexit negotiations.^[197] Despite initial approval from a majority of EU states, May's proposal was blocked by Council President Tusk alongside member state Germany.^[198]

In January 2017, the Prime Minister presented 12 negotiating objectives and confirmed that the UK government would not seek permanent single market membership.^[199] She also called for an end to ECJ jurisdiction, a new customs agreement excluding the common external tariff and the EU's common commercial policy, an end to free movement of people, co-operation in crime and terrorism, collaboration in areas of science and technology, engagement with devolved administrations, maintaining the Common Travel Area with Ireland, and preserving existing workers' rights. She also confirmed, "that the Government will put the final deal that is agreed between the UK and the EU to a meaningful vote in both Houses of Parliament, before it comes into force."^[200] The European Parliament's lead negotiator, Guy Verhofstadt, responded that there could be no "cherry-picking" by the UK in the talks.^[201]

The statutory period for negotiation began on 29 March 2017, when the UK formally submitted a letter notifying withdrawal. The letter called for a "deep and special relationship" between the UK and the EU, and warned that failure to reach an agreement would result in EU-UK trade under World Trade Organization (WTO) terms, and a weakening of the UK's co-operation in the fight against crime and terrorism. The letter suggested prioritising an early deal on the rights of EU citizens in the UK and vice versa, and stated that the UK would not seek to remain within the ESM. Instead, the UK would seek a free trade agreement with the EU.^[202] In response, Merkel insisted that the EU would not discuss future cooperation without first settling the terms of leaving the EU; Verhofstadt referred to the letter as "blackmail" with regard to the point on security and terrorism, and EU Commission President Juncker said the UK's decision to no longer be a part of the Union was a "choice they will regret one day".^[203]

The UK and EU negotiators agreed that initial negotiations, relating especially to residency rights, would commence in June 2017 (immediately after the French presidential and parliamentary elections), and full negotiations, relating especially to trading agreements, could commence in October 2017 (immediately after the 2017 German federal election).^{[204][205][206]} The first day of talks was 19 June 2017.^[205]

On 29 April 2017, immediately after the first round of French presidential elections, the remaining 27 member states' heads of government accepted negotiating guidelines prepared by Tusk.^[207] The guidelines took the view that Article 50 permitted a two-phased negotiation, in which the UK first agrees to a financial commitment and to lifelong benefits for EU citizens in Britain, and then negotiations on a future relationship could begin.^[208] In the first phase, the member states would demand the UK pay a "divorce bill", initially estimated as amounting to £52 billion^[209] and then, after additional financial demands from Germany, France, and Poland, to £92 billion.^[210] A report of the European Union Committee of the British House of Lords, published on 4 March 2017, stated that if there were to be no post-Brexit deal at the end of the negotiating period, the UK could withdraw without payment.^[211]

On 22 May 2017, the European Council authorised its negotiators to start the Brexit talks and it adopted its negotiating directives.^[212] The first day of talks took place on 19 June, where Davis and Michel Barnier, European Chief Negotiator for Brexit, agreed to prioritise the question of residency rights, while Davis conceded that a discussion of the Northern Irish border would have to await future trade agreements.^[213]

On 22 June 2017, Prime Minister May guaranteed that no EU citizen living legally in the UK would be forced to leave, and offered that any EU citizen who lived in the UK for more than five years until an unspecified deadline between March 2017 and March 2019 would enjoy the same rights as a UK citizen, conditional on the EU providing the same offer to British citizens living legally in the EU.^[214] The Prime Minister detailed her residency proposals on 26 June, but drew no concessions from EU negotiators,^[215] who had declined to expedite agreement on expatriates by the end of June 2017,^[216] and who are hoping for European courts to continue to have jurisdiction in the UK with regards to EU citizens, according to their negotiation aims published in May 2017.^[217][218]

The second round of negotiations began in mid-July 2017. Progress was made on the Northern Irish border question; UK negotiators requested a detailed breakdown of the "divorce bill" demand; and the EU negotiators criticised the UK's citizenship rights offer.^[219] David Davis did not commit to a net payment by the UK to the EU with regards to the requested divorce bill, while Michel Barnier would not compromise on his demand for the ECJ to have continuing jurisdiction over the rights of EU citizens living in the UK after Brexit,^[220] rejecting the compromise proposal of a new international body made up of UK and EU judges.^[221]

On 16 August 2017, the UK government disclosed the first of several papers detailing British ambitions following Brexit, discussing trade and customs arrangements.^[222] On 23 August Prime Minister May announced that Britain would leave the ECJ's direct jurisdiction when the planned transition period ended, but that both the British courts and the ECJ would also keep "half an eye" on each other's rulings afterwards as well.^[223] One of the UK government's position papers published in August called for no additional restrictions for goods already on the market in the UK and EU.^[224]

The third round of negotiations began on 28 August 2017. There was disagreement over the financial settlement; The Irish Times explained that British negotiators referred to the seven-year Multi-annual Financial Framework (MFF or Maff) for the period 2014–2020 agreed by member states and the European parliament as a "planning tool" for the next period rather than a legally-binding financial obligation on member states. The British case is that the MFF sets ceilings on spending under various headings and is later radically revised during the annual budget process when real legal obligations on each state arise. This contrasts with the EU Commission's methodology for calculating the UK Brexit bill which involves dividing the MFF into the shares historically agreed by each member state.^[225] On the Irish border question there was a "breakthrough", with the British side guaranteeing free movement of EU citizens within the common travel area constituting Ireland and the UK.^[226]

On 5 September 2017, Davis said that "concrete progress" had been made over the summer in areas such as protecting the rights of British expats in the EU to access healthcare and over the future of the Irish border, while significant differences over the "divorce bill" remained.^[227] On 9 September, the EU Commission published several negotiating papers, including one in which the EU concedes/declares that it is the responsibility of the UK to propose solutions for the post-Brexit Irish border. The paper envisages that a "unique" solution would be permissible here; in other words, any such exceptional Irish solution would not necessarily be a template for post-Brexit relationships with the other EU member states.^[228]

On 22 September 2017, May announced further details of her Brexit proposal.^[229][230] In addition to offering €20 billion over a two-year transition period and continued acceptance of European immigrants,^[231] she also offered a "bold new security relationship" with the EU which would be "unprecedented in its depth" and to continue to make "an ongoing contribution" to projects considered greatly to the EU and UK's advantage, such as science and security projects.^[230][229] She also confirmed that the UK would not "stand in the way" of Juncker's proposals for further EU integration.^[230][229] Barnier welcomed May's proposal as "constructive,"^[232] but that it also "must be translated into negotiating positions to make meaningful progress".^[232] Similarly, President of France Emmanuel Macron was adamant that the EU would not begin negotiations on future EU-UK relationships until "the regulation of European citizens, the financial terms of the exit, and the questions of Ireland" were "clarified" by the UK.^[233]

The fourth round of talks began on 25 September, with Barnier declaring he had no mandate from the EU27 to discuss a transition deal suggested by Prime Minister May. Davis reiterated that the UK could honour commitments made during its EU membership only in the context of a future "special partnership" deal with the EU.^[234]

At the European Council meeting of 19/20 October 2017, the 27 leaders of the EU states were to decide whether or not to start trade negotiations with the UK.^[224] However, Davis has conceded that so soon after the German elections on 24 September, a German coalition government may not be in place in time for making this decision in October, delaying any European Council decision until their December meeting.^[235][236]

EU negotiators have stated that an agreement must be reached between Britain and the EU by October 2018 in order to leave time for national parliaments to endorse Brexit.^[232]

On 9 October 2017, May announced to the British Parliament that Britain could operate as an "independent trading nation" after Brexit if no trade deal is reached with the EU.^[237]

In December 2017, EU leaders announced an agreement to begin the next phase of negotiations, with talks on a transition period after March 2019 to begin in early 2018 and discussions on the future UK–EU relationship, including trade and security, to begin in March.^[238]

On 10 June 2018, the Irish Prime Minister Leo Varadkar cleared the path for the June negotiations by postponing the Irish border question until the final Brexit deal in October 2018.^[239]

On 19 June 2018, the UK and the EU published a joint statement outlining agreements at the negotiators' level. Michel Barnier praised the "dedication and commitment" of the negotiating teams, and said progress had been made in issues like customs, VAT and the European nuclear agreement, Euratom.^[240][241]

On 12 July 2018, Prime Minister May and part of the cabinet published a proposal for an agreement on future relations between the UK and EU. Its nickname came to be known by various British media outlets as the Chequers plan. It was finalised at a meeting of the UK Cabinet held at Chequers on 6 July. Brexit Secretary David Davis resigned over the agreement on 8 July,^[242] while former Foreign Secretary Boris Johnson followed him the next day,^[243] saying that the government allowed "a fog of self-doubt" to fall on its negotiations.^[244]

On 14 November 2018, a lengthy meeting of the Cabinet approved a Draft Withdrawal Agreement.^[245][246] The following day, Brexit Secretary Dominic Raab, his Cabinet colleague Esther McVey and several junior ministers resigned their posts because of their disagreement with the contents of the document.^[247]

On 19 December 2018, the EU Commission announced its "no-deal" Contingency Action Plan in specific sectors, in respect of the UK leaving the EU "in 100 days' time."^[248]

In the wake of the United Kingdom's vote to leave the European Union, the Department for International Trade (DIT) for striking and extending trade agreements between the UK and non-EU states was created by Prime Minister May, shortly after she took office on 13 July 2016.^[249] By 2017, it employed about 200 trade negotiators^[250] and was overseen by the Secretary of State for International Trade, currently Liam Fox. In March 2019, the UK government announced that it would cut many import tariffs to zero, in the event of a no-deal Brexit.^[251] The Confederation of British Industry said the move would be a "sledgehammer for our economy",^{[252][253][254]} and the National Farmer's Union was also highly critical.^[255] Additionally, the plan appeared to breach standard WTO rules.^{[256][252][257][258][259][260]}

Following an unprecedented vote on 4 December 2018, MPs ruled that the UK government was in contempt of parliament for refusing to provide to Parliament the full legal advice it had been given on the effect of its proposed terms for withdrawal.^[261] The key point within the advice covered the legal effect of the "backstop" agreement governing Northern Ireland, the Republic of Ireland and the rest of the UK, in regard to the customs border between the EU and UK, and its implications for the Good Friday agreement which had led to the end of the Troubles in Northern Ireland, and specifically, whether the UK would be certain of being able to leave the EU in a practical sense, under the draft proposals.

The following day, the advice was published. The question asked was, "What is the legal effect of the UK agreeing to the Protocol to the Withdrawal Agreement on Ireland and Northern Ireland in particular its effect in conjunction with Articles 5 and 184 of the main Withdrawal Agreement?" The advice given was that:^[261]

On 10 December 2018, the Prime Minister postponed the vote in the House of Commons on her Brexit deal. The announcement came minutes after the Prime Minister's Office confirmed the vote would be going ahead.^[262] Faced with the prospect of a defeat in the House of Commons, this option gave May more time to negotiate with Conservative backbenchers and the EU, even though they had ruled out further discussions.^[263] The decision was met with calls from many Welsh Labour MPs for a motion of no confidence in the Government.^[264] The Leader of the Opposition, Jeremy Corbyn, described the government as being in "disarray".

The European Research Group (ERG), the segment of the Conservative Party that favours a "hard" Brexit, opposed the Prime Minister's proposed Withdrawal Agreement treaty. Its members objected strongly to the Withdrawal Agreement's inclusion of the Irish backstop.^[265][266] ERG members also objected to the proposed £39 billion financial settlement with the EU and stated that the agreement would result in the UK's agreement to continuing to follow EU regulations in major policy areas; and to the continuing jurisdiction of the ECJ over interpretation of the agreement and of European law still applicable to the UK.^[267][268]

Sir Ivan Rogers, the UK ambassador to the EU at the time of the 2016 referendum, publicly commented on 13 December 2018 that the EU was always adroit at reframing things that have already been agreed, such as the Irish backstop, in ways that "make the medicine slip down".^[269]

On 15 January 2019, the House of Commons voted 432 to 202 against the deal, which was the largest majority against a United Kingdom government ever.^{[270][271][272]} Soon after, a motion of no confidence in Her Majesty's Government was tabled by the opposition,^[273] which was rejected by 325 votes to 306.^[274]

On 24 February, Prime Minister May announced that the next vote on the withdrawal agreement would be on 12 March 2019, 17 days away from Brexit.^[275] The deal was voted against 391 to 242, a loss of 149 votes down from 230 from when the deal was proposed in January.^[276]

On 20 March 2019, the Prime Minister wrote to European Council President Tusk requesting that Brexit be postponed until 30 June 2019.^[277] On 21 March 2019, May presented her case to a European Council summit meeting in Brussels. After May left the meeting, a discussion amongst the remaining EU leaders resulted in the rejection of 30 June date and offered instead a choice of two new alternative Brexit dates. On 22 March 2019, the extension options were agreed between the UK government and the European Council.^[187] The first alternative offered was that if MPs rejected May's deal in the next week, Brexit would be due to occur by 12 April 2019, with, or without, a deal—or alternatively another extension be asked for and a commitment to participate in the 2019 European Parliament elections given. The second alternative offered was that if MPs approved May's deal, Brexit would be due to occur on 22 May 2019. The later date was the day before the start of European Parliament elections.^[278] After the government deemed unwarranted the concerns over the legality of the proposed change (due to its containing two possible exit dates) the previous day,^[279][280] on 27 March 2019 both the Lords (without a vote)^[281] and the Commons (by 441 to 105) approved the statutory instrument changing the exit date to 22 May 2019 if a withdrawal deal is approved, or 12 April 2019 if it is not.^[282] The amendment was then signed into law at 12:40 p.m. the next day.^[187]

On 18 March 2019, the Speaker informed the House of Commons that a third meaningful vote could only be held on a motion that was significantly different from the previous one, citing parliamentary precedents going back to 1604.^[283]

The Withdrawal Agreement was brought back to the House without the attached understandings on 29 March.^[284] The Government's motion of support for the Withdrawal Agreement was lost by 344 votes to 286, a loss of 58 votes down from 149 from when the deal was proposed on 12 March.^[285]

Following the failure of the UK Parliament to approve the Withdrawal Agreement by 29 March, the UK was required to leave the EU on 12 April 2019. On 10 April 2019, late-night talks in Brussels resulted in a further extension, to 31 October 2019; Theresa May had again only requested an extension until 30 June. Under the terms of this new extension, if the Withdrawal Agreement were to be passed before October, Brexit would occur on the first day of the subsequent month. However, the UK would be obligated to hold European Parliament elections in May, or leave the EU on 1 June without a deal.^[154][155]

The UK Parliament has passed a bill obliging the Prime Minister to seek a third extension if no agreement has been reached at the next European Council meeting.^[286]

In October 2016, Theresa May promised a "Great Repeal Bill", which would repeal the European Communities Act 1972 and restate in UK law all enactments previously in force under EU law. Subsequently renamed the European Union (Withdrawal) bill, it was introduced to the House of Commons on 13 July 2017.^[287]

On 12 September 2017, the bill passed its first vote and second reading by a margin of 326 votes to 290 votes in the House of Commons.^[288] The bill was further amended on a series of votes in both Houses of Parliament. After the Act became law on 26 June 2018, the European Council decided on 29 June to renew its call on Member States and Union institutions to step up their work on preparedness at all levels and for all outcomes.^[289]

The Withdrawal Act fixed the period ending 21 January 2019 for the government to decide on how to proceed if the negotiations have not reached agreement in principle on both the withdrawal arrangements and the framework for the future relationship between the UK and EU; while, alternatively, making future ratification of the withdrawal agreement as a treaty between the UK and EU depend upon the prior enactment of another act of Parliament for approving the final terms of withdrawal when the current Brexit negotiations are completed. In any event, the act does not alter the two-year period for negotiating allowed by Article 50 that ends at the latest on 29 March 2019 if the UK has not by then ratified a withdrawal agreement or agreed a prolongation of the negotiating period.^[188]

The Withdrawal Act which became law in June 2018 allows for various outcomes including no negotiated settlement. It authorises the government to bring into force, by order made under section 25, the provisions that fix "exit day" and the repeal of the European Communities Act 1972, but exit day must be the same day and time as when the EU Treaties are to cease to apply to the UK.^[290]

A report published in March 2017 by the Institute for Government commented that, in addition to the European Union (Withdrawal) bill, primary and secondary legislation will be needed to cover the gaps in policy areas such as customs, immigration and agriculture.^[291] The report also commented that the role of the devolved legislatures was unclear, and could cause problems, and as many as 15 new additional Brexit Bills may be required, which would involve strict prioritisation and limiting Parliamentary time for in-depth examination of new legislation.^[292]

In 2016 and 2017, the House of Lords published a series of reports on Brexit-related subjects, including:

The Nuclear Safeguards Act 2018, relating to withdrawal from Euratom, was presented to Parliament in October 2017. The act makes provision about nuclear safeguards, and for connected purposes. The Secretary of State may by regulations (“nuclear safeguards regulations”) make provision for the purpose of — (a) ensuring that qualifying nuclear material, facilities or equipment are only available for use for civil activities (whether in the UK or elsewhere), or (b) giving effect to provisions of a relevant international agreement.^[293]

A general election was held on 8 June 2017, announced at short notice by the new Prime Minister May. The Conservative Party, Labour and UKIP made manifesto pledges to implement the referendum, although the Labour manifesto differed in its approach to Brexit negotiations, such as unilaterally offering permanent residence to EU immigrants.^{[294][295][296][297]} The Liberal Democrat Party and the Green Party manifestos proposed a policy of remaining in the EU via a second referendum.^{[298][299][300]} The Scottish National Party (SNP) manifesto proposed a policy of waiting for the outcome of the Brexit negotiations and then holding a referendum on Scottish independence.^[301][302] Compared to the 2015 general election, the Conservatives gained votes (but nevertheless lost seats and their majority in the House of Commons). Labour gained significantly on votes and seats, retaining its position as the second-largest party. The Democratic Unionist Party (DUP) and Sinn Féin also made gains in votes and seats. Parties losing votes included the SNP, Liberal Democrats, Greens, and especially UKIP.^[303]

On 26 June 2017, Conservatives and the DUP reached a confidence and supply agreement whereby the DUP would back the Conservatives in key votes in the House of Commons over the course of the parliament. The agreement included additional funding of £1 billion for Northern Ireland, highlighted mutual support for Brexit and national security, expressed commitment to the Good Friday Agreement, and indicated that policies such as the state pension triple lock and Winter Fuel Payments would be maintained.^[304]

Opinion polling tended to show a plurality of support for Brexit after the referendum and until the 2017 General Election. Since then, opinion polls have tended to show a plurality of support for remaining in the EU or for the view that Brexit was a mistake. This seems to be largely due to a preference for remaining in the EU among those who did not vote in 2016's referendum (an estimated 2 million of whom, as of March 2019, were too young to vote at the time^[305]).^[306] In March 2019, a petition submitted to the UK Parliament petitions website, calling on the government to revoke Article 50 and stay in the EU, reached a record-level of over six million, one hundred thousand signatures.^[307][308]

Whether the UK leaves with a withdrawal agreement or alternatively without any withdrawal agreement ("no-deal" Brexit) will affect future impacts, particularly in connection with the location of EU agencies and the regulation and control of cross-border outward and inward movements of persons and animals, of goods for export and import, and of financial and other transactions.^[68]

According to a 2016 study by Ken Mayhew, Emeritus Professor of Education and Economic Performance at Oxford University, Brexit posed the following threats to higher education: "loss of research funding from EU sources; loss of students from other EU member states; the impact on the ability of the sector to hire academic staff from EU member states; and the impact on the ability of UK students to study abroad."^[309] The UK received more from the European agencies and institutions for research than it financially contributed^[310][311] with universities getting just over 10% of their research income from the European agencies and institutions.^[312] All funding for net beneficiaries from European agencies and institutions, including universities, was guaranteed by the British government in August 2016.^[313] Currently, the UK is part of the European Research Area and the UK is likely to wish to remain an associated member.^[314]

The United Kingdom and Republic of Ireland have been part of the Common Travel Area since before the EU was formed. This allows their citizens freedom of movement within the area, with only passport checks at airports and seaports. Their membership of the EU Customs Union and Single Market means there are no customs checks or tariffs. Since 2005, the border has been essentially invisible.^[315]

After Brexit, the border between Northern Ireland (part of the UK) and the Republic of Ireland (part of the EU) will become the only UK–EU land border. There is concern about whether this becomes a "hard border" with fewer, controlled crossing points and customs checks.^[316] This could compromise the Good Friday Agreement that ended the Northern Ireland conflict,^{[317][318][319]} and lead to violence.^[320] All involved parties agree a hard border should be avoided.^[321] To forestall this, the EU proposed a "backstop agreement" (the Northern Ireland Protocol) that would keep the UK in the Customs Union and keep Northern Ireland in some aspects of the Single Market also, until a lasting solution is found.^[322] The backstop is supported by the Irish government and Irish nationalists, but opposed by Ulster unionists and many Conservatives. They say it undermines the UK's territorial integrity, prevents it making its own trade deals, and fear it could keep the UK (or part of it) under EU rules indefinitely.^[322] The backstop is part of the Withdrawal Agreement, but the UK parliament overwhelmingly voted down the agreement and the government seeks to replace it with other arrangements.^[322]

Following opposition from the Democratic Unionist Party (DUP) to the backstop, Theresa May agreed to keep the whole UK in the customs union, should it come in effect.^[322] When Boris Johnson became Prime Minister, he promised to remove the backstop from the withdrawal agreement and replace it with "alternative arrangements".^[323] One proposed option is for Northern Ireland alone continuing to follow EU food standards. Under EU rules, food products must be checked at their point-of-entry to the EU, which would mean food products coming from Great Britain to Northern Ireland would be subject to new checks. Unionists have not ruled this out, but the Irish government said it is "not enough on its own".^[322] Other proposed options include trusted traders schemes and using GPS to track lorries. Some trade experts have said trusted-trader schemes would not be enough alone to end all border checks, and the technological solutions including GPS tracking may increase the costs and complexity of trade. The EU has committed to working on alternative arrangements, and Angela Merkel said the withdrawal agreement would not need to be renegotiated if a practical solution to the backstop could be found, but such arrangements may take years to become fully operational, and would require agreement from the EU and the Irish government.^[323]

The UK government announced that it would not perform customs checks at the Irish border after a no-deal Brexit and acknowledged that that might present a smuggling risk.^{[256][324][325]} European Commission President, Jean-Claude Juncker, said if there was a no-deal Brexit the Republic of Ireland would have to implement border checks on the EU's behalf.^[326] On 17 March, the President of Ireland signed into law the Withdrawal of the United Kingdom from the European Union (Consequential Provisions) Act 2019.^[327]

The French and British governments say they remain committed to the Le Touquet Agreement, which lets UK border checks be completed in France, and vice-versa (juxtaposed controls).^[328] The two governments signed the Sandhurst Treaty in January 2018, which will shorten the time taken to process migrants attempting to reach the UK from Calais, from six months to one month. The UK also announced it will invest a further £44.5 million on border security at the English Channel.^[328]

If there is a "no-deal" Brexit, trade between the UK and France will default to World Trade Organization rules. To ensure the smooth flow of freight, France created a new "smart border" which will scan trucks' licence plates and automatically link them to shipping documents filled out online by exporters. Trucks travelling to Britain will either be waved through, or undergo checks if they carry food, plants or livestock. Gérald Darmanin, French Minister of Public Action and Accounts, said there would not be long queues in Calais.^[329] France is spending €50 million on expanding port infrastructure and plans to recruit 700 more customs staff by the end of 2020.^[330]

Economists expect that Brexit will have damaging immediate and longer term effects on the economies of the UK and at least part of the EU27. In particular, there is a broad consensus among economists and in the economic literature that Brexit will likely reduce the UK's real per capita income in the medium and long term, and that the Brexit referendum itself damaged the economy.^[2][331]

According to one study, the referendum result had pushed up UK inflation by 1.7 percentage points in 2017, leading to an annual cost of £404 for the average British household.^[332] Studies published in 2018, estimated that the economic costs of the Brexit vote were 2.1% of GDP,^[333][334] or 2.5% of GDP.^[335] According to a December 2017 Financial Times analysis, the Brexit referendum results had reduced national British income by between 0.6% and 1.3%.^[336] A 2018 analysis by Stanford University and Nottingham University economists estimated that uncertainty around Brexit reduced investment by businesses by approximately 6 percentage points and caused an employment reduction by 1.5 percentage points,^[337] and a September 2019 study by the same authors and others concluded that since the referendum there has been an increase in uncertainty amongst businesses and that this, in addition to time dedicated to Brexit planning, has reduced UK productivity by between 2% and 5%, and reduced investment by 11%.^[338] A number of studies found that Brexit-induced uncertainty about the UK's future trade policy reduced British international trade from June 2016 onwards.^{[339][340][341][342][343]} A 2019 analysis found that British firms substantially increased offshoring to the EU after the Brexit referendum, whereas European firms reduced new investments in the UK.^[344][345]

There is overwhelming or near-unanimous agreement among economists that leaving the EU will adversely affect the British economy in the medium- and long-term.^[3][331] Surveys of economists in 2016 showed overwhelming agreement that Brexit would likely reduce the UK's real per-capita income level.^[10][11][12] 2019 and 2017 surveys of existing academic research found that the credible estimates ranged between GDP losses of 1.2–4.5% for the UK,^[331] and a cost of between 1–10% of the UK's income per capita.^[8] These estimates differ depending on whether the UK exits the EU with a hard Brexit or soft Brexit.^[8] In January 2018, the UK government's own Brexit analysis was leaked; it showed that UK economic growth would be stunted by 2–8% in total over the 15 years following Brexit, the amount depending on the leave scenario.^[346][347]

According to most economists, EU membership has a strong positive effect on trade and as a result the UK's trade would be worse off if it left the EU.^{[348][349][350][351]} According to a study by University of Cambridge economists, under a "hard Brexit" whereby the UK reverts to WTO rules, one-third of UK exports to the EU would be tariff-free, one-quarter would face high trade barriers and other exports risk tariffs in the range of 1–10%.^[352] A 2017 study found that "almost all UK regions are systematically more vulnerable to Brexit than regions in any other country."^[353] A 2017 study examining the economic impact of Brexit-induced reductions in migration" found that there would likely be "a significant negative impact on UK GDP per capita (and GDP), with marginal positive impacts on wages in the low-skill service sector."^[354][8] It is unclear how changes in trade and foreign investment will interact with immigration, but these changes are likely to be important.^[8]

With Brexit, the EU would lose its second-largest economy, the country with the third-largest population and "the financial capital of the world", as the German newspaper Münchner Merkur put it.^[355] Furthermore, the EU would lose its second-largest net contributor to the EU budget (2015: Germany €14.3 billion, UK €11.5 billion, France €5.5 billion).^[356] Thus, the departure of Britain would result in an additional financial burden for the remaining net contributors, unless the budget is reduced accordingly: Germany, for example, would have to pay an additional €4.5 billion for 2019 and again for 2020; in addition, the UK would no longer be a shareholder in the European Investment Bank, in which only EU members can participate. Britain's share amounts to 16%, €39.2 billion (2013), which Britain would withdraw unless there is an EU treaty change.^[357]

All the remaining EU members (as well as EFTA countries – Switzerland, Norway, and Iceland) will also likely experience adverse effects (albeit smaller effects than the UK), in particular Ireland, the Netherlands and Belgium.^{[358][359][360]}

Short-term macroeconomic forecasts by the Bank of England and other banks of what would happen immediately after the Brexit referendum were also pessimistic.^[14][361] The assessments assumed that the referendum results would create greater uncertainty in markets and reduce consumer confidence more than it did.^[361] A number of economists noted that short-term macroeconomic forecasts are generally considered unreliable and that they are something that academic economists do not do, unlike banks.^{[362][363][361][8][14]} Economists have compared short-term economic forecasts to weather forecasts whereas the long-term economic forecasts are akin to climate forecasts: the methodologies used in long-term forecasts are "well-established and robust".^{[361][362][8][364]}

Studies on the economic impact that different forms of Brexit will have on different parts of the country indicate that Brexit will exacerbate regional economic inequality in the UK, as already struggling regions will be hardest hit by Brexit.^[365]

Early reports from economists warned that London's future as an international financial centre depended on whether the UK would obtain passporting rights for British banks from the EU, suggesting that if banks located in the UK were not able to obtain them, they would have strong incentives to relocate to alternative financial centres within the EU.^[366][367] According to John Armour, Professor of Law and Finance at Oxford University, in March 2017, "a 'soft' Brexit, whereby the UK leaves the EU but remains in the single market, would be a lower-risk option for the British financial industry than other Brexit options," since passporting rights would continue.^[367] In August 2019 a report prepared by the Central Bank of Ireland indicated that the impact of Brexit on London's financial sector could be very small due to the premium London enjoys, and that the City of London is likely to remain a very large global financial centre even in adverse Brexit scenarios.^[368]

According to a 2017 study by the University of Exeter and Chatham House researchers, there are considerable benefits for the UK to be integrated into the European energy market. The authors of the study said, "if the UK wants to enjoy the economic benefits of remaining part of what is an increasingly integrated European electricity market then, as European legislation is currently drafted, it will not only have to forgo an element of autonomy through accepting legislation and regulations made collectively at the EU level, but it will also lose much of its voice in that decision making process, effectively becoming a rule-taker rather than a rule-maker."^[369]

Analyses indicate that the departure of the relatively economically liberal UK will reduce the ability of remaining economically liberal countries to block measures in the Council of the EU.^[370][371] According to the Lisbon Treaty (2009), decisions of the Council are made by qualified majority voting, which means that a majority view can be blocked should at least four members of the Council, representing at least 35% of the population of the Union, choose to do so. In many policy votes, Britain, allied with other northern EU allies (Germany, Ireland, the Netherlands, and the Scandinavian and the Baltic states), had a blocking minority of 35%.^[372][373]

UK MEPs are expected to retain full rights to participate in the European Parliament up to the Article 50 deadline. However, there have been discussions about excluding UK MEPs from key committee positions.^[374]

In April 2017, a group of European lawmakers discussed what should be done about the vacated seats when the UK leaves the EU. One plan, supported by Gianni Pittella and Emmanuel Macron, is to replace the 73 seats with a pan-European constituency list; other options which were considered include dropping the British seats without replacement, and reassigning some or all of the existing seats from other countries to reduce inequality of representation.^[375][376]

After Brexit, the UK will leave the Common Agricultural Policy (CAP),^[377] which provides financial support to farmers in the EU. Most of the payments to farmers comes from the EU budget, paid for by contributions from member states.^[378] However, the UK receives much less than it contributes, and the CAP has been criticised for encouraging farming which harms the environment, favouring big landowners and imposing high food prices.^[378]

Brexit allows the UK to develop its own agriculture policy.^[379] The UK government and devolved legislatures have set out plans to support farmers while enhancing the environment.^[379] The current UK government has committed to maintaining the same payments to farmers until the end of the current parliament, even without a withdrawal agreement.^[377] The Agriculture Bill is intended to replace the CAP with a new system based on paying farmers "public money for public goods" such as environmental protection, public access to the countryside and measures to reduce flooding. The UK government has also said it will ensure continued "access to seasonal agricultural labour" from abroad after Brexit.^[379] Farming unions have warned that a "no-deal" Brexit, however, could have "severe impacts" on farming.^[380]

After Brexit, the UK will leave the Common Fisheries Policy (CFP)^[381] that lets all EU countries fish within 12 nautical miles of the UK coast^[382] and lets the EU set catch quotas.^[383] The UK fishing industry has long criticised the CFP,^[384] arguing that it favours non-UK fishermen because the UK has a larger fishing zone than most of its neighbours.^[383] The combined EU fishing fleets land about 6 million tonnes of fish per year,^[385] about half of which are from UK waters.^[386] The UK's share of the overall catch is only 750,000 tonnes.^[387]

The UK will become an independent coastal state and be fully responsible for managing fisheries in its Exclusive Economic Zone (EEZ), extending 200 nautical miles (nm) from shore.^[381] It will still be bound by the UN Law of the Sea Convention, which requires it to co-operate with neighbours on managing shared fish stocks and prevent overfishing.^[381] By leaving the CFP, the UK could develop fisheries policy that better suits its needs.^[383] The UK will also leave the London Fisheries Convention that lets Irish, French, Belgian, Dutch and German vessels fish within six nautical miles of the UK's coast.^[388] This was welcomed by the National Federation of Fishermen's Organisations and the Scottish government,^[389] but the Irish fishing industry expressed concern as a third of its catch is from UK waters.^[390]

Access for foreign fishing vessels to UK waters will be a matter for negotiation.^[381] According to Wageningen Economic Research, if there was a "hard Brexit that banned EU fishermen from UK waters", British fishermen could catch more fish but the price of their fish would drop, while the resulting trade barriers would lead to higher seafood prices for consumers, because the UK imports most of its seafood. This would be a "lose-lose situation" for both the UK and the EU, and for both British consumers and the fishing industry.^[391] According to a 2018 study, "Brexit poses a major challenge to the stability of European fisheries management [...] potentially putting at risk recent recovery and future sustainability of shared fish stocks". It said that denying access to foreign fishing vessels would risk tariffs being imposed, while granting access and seeking a more modest re-balancing of fishing entitlements would lessen this risk.^[392]

Gibraltar, a British Overseas Territory, participated in the referendum and will leave the EU together with the UK, although 96% of those who participated in the referendum in Gibraltar voted to remain. Gibraltar is outside the EU Customs Union and Schengen Zone, meaning it has customs and identity checks at its border with Spain.

Spain asserts a territorial claim on Gibraltar. After the referendum, Spain's Foreign Minister renewed calls for joint Spanish–British control.^[393] This was rebuffed by Gibraltar's Chief Minister,^[394] and the UK government states it would only negotiate on Gibraltar's sovereignty with the consent of its people.^[395]

The European Council's guidelines for withdrawal negotiations stated that UK–EU agreements made after Brexit would not apply to Gibraltar without Spain's consent.^[396] Gibraltarian government minister (and former Chief Minister) Joe Bossano condemned the EU's attitude, suggesting that Spain was being offered a veto, adding "It's enough to convert me from a supporter of the European Union into a Brexiteer".^[397]

In late 2018, the British and Spanish governments agreed that any dispute over Gibraltar would not affect Brexit negotiations,^[398] and the British government agreed that UK–EU treaties made after Brexit would not automatically apply to Gibraltar.^[399] Spanish Prime Minister Pedro Sánchez said that "With Brexit we all lose, especially the United Kingdom, but when it comes to Gibraltar, Spain wins."^[400][401]

A 2019 study in the Lancet suggested that Brexit would have an adverse impact on health in the UK under every Brexit scenario, but that a no-deal Brexit would have the worst impact.^[402] The study found that Brexit would deplete the National Health Service (NHS) workforce, create uncertainties regarding care for British nationals living in the EU, and put at risk access to vaccines, equipment, and medicines.^[402] Supplies of life saving medications including cancer medication could be disrupted for up to six months under a no-deal Brexit. The Department of Health and Social Care stated in August 2019 that steps are being taken to ensure the supply of medicines and medical products remains uninterrupted after Brexit.^[403]

After Brexit, the UK will have the final say over the laws that govern it.^[404] Under the European Union (Withdrawal) Act 2018, which was passed by the British parliament, EU laws will no longer have supremacy over UK laws after Brexit.^[405] To maintain continuity, the Act converts EU law into UK law as "retained EU law". After Brexit, the British parliament (and the devolved legislatures) can decide which elements of that law to keep, amend or repeal.^[405] Furthermore, UK courts will no longer be bound by the judgments of the EU Court of Justice after Brexit. Its case law from before Brexit will still apply to UK courts, but the UK Supreme Court will not be bound by it.^[406] According to Catherine Barnard from UK in a Changing Europe, any future trade agreement between EU and UK will require part of EU law to take precedence over UK law.^[406]

The UK's exit from the EU will leave Ireland and Cyprus as the only two remaining common law jurisdictions in the EU. Paul Gallagher, a former Attorney General of Ireland, has suggested this will isolate those countries and deprive them of a powerful partner that shared a common interest in ensuring that EU legislation was not drafted or interpreted in a way that would be contrary to the principles of the common law.^[407] Lucinda Creighton, a former Irish government minister for legal affairs, has said that Ireland relies on the "bureaucratic capacity of the UK" to understand, influence and implement EU legislation.^[408]

After Brexit, the UK would be able to control immigration from the EU and EEA.^[409] Being part of the EU and EEA means that citizens of any member state can move to the UK to live and work with very little restrictions (freedom of movement). The European Union (Withdrawal) Act 2018 retains freedom of movement as UK law until it is repealed.^[410] The Immigration and Social Security Co-ordination (EU Withdrawal) Bill would repeal free movement and make EU immigration subject to UK law.^[411] The current UK government intends to replace it with a new system. The government's 2018 white paper proposes a "skills-based immigration system" that prioritizes skilled migrants, limits the length of time low-skilled migrants can work in the UK, and applies a stricter criminality threshold. EU and EEA citizens already living in the UK can continue living there after Brexit by applying to the EU Settlement Scheme, which began in March 2019. Irish citizens will not have to apply to the scheme.^{[412][413][414]} If there is a no-deal Brexit, EU citizens who arrive in the UK before the end of 2020 can apply to stay until the end of 2023.^[415]

Studies estimating the long-term impact of Brexit on immigration note that many factors affect future migration flows but that Brexit and the end of free movement will likely result in a large decline in immigration from EEA countries to the UK.^[416][417] The Migration Policy Institute estimated immediately after the referendum that the UK "would continue to receive 500,000 or more immigrants (from EU and non-EU countries taken together) per year, with annual net migration around 200,000".^[418] The decline in EEA immigration is likely to have an adverse impact on the British health sector.^[419]

Official figures for June 2017 (published in February 2018) showed that net non-British EU immigration to the UK slowed to about 100,000 immigrants per year (corresponding to the immigration level of 2014) while immigration from outside the European Union increased. Taken together, the two inflows into the UK resulted in an only slightly reduced net immigration of 230,000 newcomers in the year to June 2017. The Head of the Office of National Statistics suggested that Brexit could well be a factor for the slowdown in EU immigration, but cautioned there might be other reasons.^[420] The number of non-British EU nurses registering with the NHS fell from 1,304 in July 2016 to 46 in April 2017.^[421]

Since the referendum, British citizens have attempted to ensure their retention of EU citizenship via a number of different mechanisms, including applying to other EU member states for citizenship,^[422][423] and petitioning the European Commission.^[424]

Currently, EEA sportspersons face minimal bureaucracy to play or perform in the UK. After Brexit, any foreigner wanting to do so more than temporarily could need a work permit. Such work permits can be tricky to obtain, especially for young or lower ranked players. Conversely, British nationals playing in EEA states may encounter similar obstacles where none exist today.^[425][426]

Brexit requires the offices and staff of the European Medicines Agency and European Banking Authority, currently based in London, to move out of the UK.^[427] The agencies, which together employ more than 1,000 people, will respectively move to Amsterdam and Paris.^[428]

By leaving the EU, the UK would leave the European Common Aviation Area (ECAA), a single market in commercial air travel.^[429] The UK will negotiate a future relationship with the EU on the "basis of equivalence of traffic rights and a level playing field".^[430] It could negotiate an agreement to re-join as a non-EU member (like Bosnia and Herzegovina), negotiate access through a bilateral agreement (like Switzerland), or negotiate a new 'open skies' bilateral deal with the EU.^[429] If there is a "no-deal" Brexit, UK airlines will still have permission to operate within the EU with no restrictions, and vice-versa. UK airlines licensed before Brexit will still have permission to operate provided they are majority owned and effectively controlled by nationals of the UK and/or nationals of the EU and EEA.^[430]

The UK government seeks continued participation in the European Aviation Safety Agency (EASA). If there is a "no-deal" Brexit, the UK's Civil Aviation Authority would take on the role of regulator for UK airlines. A substantial increase in CAA staff and resources would be needed to meet the demands of its new role.^[429]

The UK has its own air service agreements with 111 countries, which permit flights to-and-from the country, and these will continue after Brexit. It has air service agreements with a further 17 countries through its EU membership, and it has sought to replace these.^[431] By July 2019, the UK had concluded air service agreements with the United States,^[432] Canada^[432] Switzerland,^[433] Albania, Georgia, Iceland, Israel, Jordan, Kosovo, Moldova, Montenegro, Morocco, North Macedonia and Norway.^[434]

The EU announced that the Channel Tunnel rail link will remain open on current terms for three months if there is a "no-deal" Brexit. The EU Commission said this should be enough time for new permanent arrangements to be agreed.^[435]

The Vienna Convention on Road Traffic is written by the UN, not the EU, allowing road traffic between the UK and EU even without a deal.

The UK will remain in the European Common Transit Convention (CTC) after Brexit.^[436] This would apply to any new trading relationship with the EU, including after exit with no Withdrawal Agreement treaty.^[437] The CTC applies to moving goods between the EU member states, the EFTA countries (Iceland, Norway, Liechtenstein and Switzerland) as well as Turkey, Macedonia and Serbia. The CTC, with its supplementary Convention on the Simplification of Formalities in the Trade of Goods, reduces administrative burdens on traders by removing the need for additional import/export declarations when transiting customs territories, and provides cash flow benefits by allowing the movement of goods across a customs territory without the payment of duties until the final destination.^[438]

In the event of a "no-deal" Brexit, the number of permits available to haulage drivers will be "severely limited": the Department for Transport proposes to allocate these by lottery.^[439] Even with a customs union, the experience of Turkish hauliers suggests that significant difficulties and delays will occur both at the border and within some countries.^[440]

Ferries will continue, but with obstacles such as customs checks.^[441] New ferry departures between the Republic of Ireland and the European mainland have been established in anticipation of the Great Britain land bridge becoming congested, mainly with France, Spain, Belgium and the Netherlands.^[441]

As suggested by the Scottish Government before the referendum,^[442] the First Minister of Scotland announced that officials were planning an independence referendum due to the result of Scotland voting to remain in the European Union when England and Wales voted to leave.^[443] In March 2017, the SNP leader and First Minister Nicola Sturgeon requested a second Scottish independence referendum in 2018 or 2019 (before Britain's formal exit from the EU).^[444] The UK Prime Minister immediately rejected the requested timing, but not the referendum itself.^[445] The referendum was approved by the Scottish Parliament on 28 March 2017. Sturgeon called for a "phased return" of an independent Scotland back to the EU.^[446]

After the referendum, First Minister Sturgeon suggested that Scotland might refuse consent for legislation required to leave the EU,^[447] though some lawyers argued that Scotland cannot block Brexit.^[448]

On 21 March 2018, the Scottish Parliament passed the Scottish Continuity Bill.^[449] This was passed due to stalling negotiations between the Scottish Government and the British Government on where powers within devolved policy areas should lie after exit day from the European Union. This Act allows for all devolved policy areas to remain within the remit of the Scottish Parliament and reduces the executive power upon exit day that the UK Withdrawal Bill provides for Ministers of the Crown.^[450] The bill was referred to the supreme court which found that it could not come into force as the European Union (Withdrawal) Act 2018, which received royal assent between the Scottish parliament passing its bill and the supreme court's judgement, designated itself under schedule 4 of the Scotland Act 1998 as unamendable by the Scottish Parliament.^[451] The bill has therefore not received royal assent.^[452]

Concerns have been raised that Brexit might create security problems for the UK. In particular in law enforcement and counterterrorism where the UK could use the European Union's databases on individuals crossing the British border. Security experts have credited the EU's information-sharing databases with helping to foil terrorist plots. British leaders have expressed support for retaining access to those information-sharing databases, but it could be complicated to obtain that access as a non-member of the EU. Brexit would also complicate extradition requests. Under a hard Brexit scenario, the UK would lose access to basic law enforcement tools, such as databases comprising European plane travel records, vehicle registrations, fingerprints, and DNA profiles.^[453]

The Financial Times said that there were approximately 759 international agreements, spanning 168 non-EU countries, that the UK would no longer be a party to upon leaving the EU.^[454] This figure does not include WTO or United Nations opt-in accords, and excludes "narrow agreements", which may also have to be renegotiated.^[454]

The UK's post-Brexit relationship with the EU could take several forms. A research paper presented to the UK Parliament in July 2013 proposed a number of alternatives to being a member state which would continue to allow access to the EU internal market. These include remaining in the European Economic Area,^[455] negotiating deep bilateral agreements on the Swiss and Norwegian model,^[456][455] or exit from the EU without EEA membership or a trade agreement under the WTO Option. There may be an interim deal between the time the UK leaves the EU and when the final relationship comes in force.

Pro-Brexit activists and politicians have argued for negotiating trade and migration agreements with the "CANZUK" countries—those of Canada, Australia, New Zealand and the United Kingdom.^[457][458] Numerous academics have criticised this alternative for EU membership as "post-imperial nostalgia".^{[459][460][461]} Economists note that distance reduces trade, a key aspect of the gravity model of trade, which means that even if the UK could obtain similar trade terms with the CANZUK countries as it had as part of the Single Market, it would be far less valuable to the UK.^{[462][463][464]}

In August 2019 the President Donald Trump pledged to negotiate a "very big trade deal" with the UK after Brexit.^[465]

Questions have arisen over how existing international arrangements with the EU under WTO terms should evolve. Some countries—such as Australia and the US—wish to challenge the basis for division (i.e., division between the UK and the continuing EU) of the trade schedules previously agreed between them and the EU, because it reduces their flexibility.^[466]

Brexit has inspired many creative works, such as murals, sculptures, novels, plays, movies and video games. The response of British artists and writers to Brexit has in general been negative, reflecting a reported overwhelming percentage of people involved in Britain's creative industries voting against leaving the European Union.^[467]