The Protocol on Ireland and Northern Ireland, which is included in the UK`s withdrawal agreement from the EU, confirmed that the Good Friday Agreement must be protected in all its parts. Unionist parties, including the Democatic Unionist Party (DUP) and the Ulster Unionist Party (UUP), oppose a vote on reunification. DUP chief Arlene Foster dismissed the prospect in February 2019 as part of the “fear of the project.” Naomi Long, chairwoman of the Intercommunal Alliance party, said she may be open to a referendum on Irish unity, but that “now is not the time.” In March 2019, the Irish Times/Ipsos MRBI poll reported that only 38% of public opinion in Northern Ireland thought there should be a referendum on Irish reunification, compared to 45% who thought it should not be the case. If there was a referendum now, 45% said they were against unity, and 32% said they would vote for it, while the remaining 23% said “don`t know”. Both views have been recognized as legitimate. For the first time, the Irish government agreed, in a binding international agreement, that Northern Ireland was part of the United Kingdom.  The Irish Constitution has also been amended to implicitly recognize Northern Ireland as part of the sovereign territory of the United Kingdom provided that the majority of the population of the island`s two jurisdictions has agreed to a unified Ireland. On the other hand, the language of the agreement reflects a change in the UK`s emphasis on the one-for-eu law to United Ireland.  The agreement therefore left open the question of future sovereignty over Northern Ireland.
 The two main political parties in the agreement were the Ulster Unionist Party (UUP), led by David Trimble, and the Social Democratic and Labour Party (SDLP), led by John Hume. The two heads of state and government together won the Nobel Peace Prize in 1998. The other parties to the agreement were Sinn Féin, the Alliance Party and the Progressive Unionist Party. The Democratic Unionist Party (DUP), which later became the largest Unionist party, did not support the agreement. When Sinn Féin and loyalist parties entered, they left the talks because republican and loyalist paramilitary weapons had not been decommissioned. In 1998, the British government enshrined the principle of self-determination in legislation and also repealed the Government of Ireland Act 1920, which first divided the island of Ireland. The Northern Ireland minister will call a referendum on a united Ireland if it is likely that a majority of the population would vote in favour of a united Ireland. If the referendum is rejected, it will take at least seven years before a new referendum can be held. The agreement called for the creation of an independent commission to review police rules in Northern Ireland, “including ways to promote broad community support” for these agreements. The UK government has also pledged to carry out a “large-scale review” of the criminal justice system in Northern Ireland.
However, their respective conceptions of the agreement brought their differences to the surface and, for a short period of time, the DUP and the organizations, under the banner of the Combined Loyalist Military Command, were vehemently opposed, the latter opposing nationalism and liberal unionism by vigorously supporting the agreement.