On November 25, 2018, Britain and the EU agreed on a 599-page withdrawal agreement, a Brexit deal that touches on issues such as civil rights, divorce law and the Irish border. Parliament voted for the first time on this agreement on Tuesday 15 January 2019. MPs voted by 432 votes to 202 to reject the deal, the biggest defeat for a government in the House of Commons in recent history. Gov.UK. “Agreement on the withdrawal of the United Kingdom of Great Britain and Northern Ireland from the European Union and the European Atomic Energy Community, as approved by the Heads of State and Government at an extraordinary European Council of 25 November 2018”, pages 20 and 28. The backstop turned out to be the main reason for the Brexit impasse. It was a guarantee that there would be no “hard border” between Northern Ireland and Ireland. It was an insurance policy that Britain held in the EU`s customs union with Northern Ireland under EU internal market rules. The backstop, which was to be temporary and to be replaced by a subsequent deal, could only be cancelled if Britain and the EU agreed. Eurosceptic MEPs wanted it to add legally binding changes, fearing it would jeopardise the country`s autonomy and take an indefinite duration. So far, EU heads of state and government have refused to withdraw them and have also ruled out a time limit or given Britain the power to withdraw it.
On 11 March 2019, the two sides signed a pact in Strasbourg that did not change the Withdrawal Agreement, but added “useful legal assurances”. This was not enough to convince Brexiteers. After an unprecedented vote, on 4 December 22, 2018, MPs decided that the UK government was not respecting Parliament because it had refused to give Parliament the full legal advice it had received on the consequences of its proposed withdrawal conditions.  The central point of the opinion concerned the legal effect of the Backstop Agreement on Northern Ireland, the Republic of Ireland and the rest of the United Kingdom with regard to the customs border between the European Union and the United Kingdom and its impact on the Good Friday Agreement that led to the end of the unrest in Northern Ireland, and in particular on the security of the United Kingdom, to be able to leave the EU in practice, in accordance with the draft proposals. . . . .