The Northern Ireland conflict first emerged in the 17th century for religious reasons. As is well known, Protestant Englishmen colonized Catholic Ireland under the leadership of Oliver Cromwell in 1653. Later on, in 1801, Ireland was incorporated into the Kingdom of Great Britain, by what is now the United Kingdom (the UK), following an unsuccessful uprising by the Irish nationalists. However, despite this merger, religious and cultural differences persisted and led to the Irish War of Independence in 1919. After the war, Ireland gained its independence in 1921 with the Anglo-Irish Treaty. However, according to the treaty, the Protestant-dominated region of Northern Ireland was left under the control of the United Kingdom.
Since the repartition of Ireland, in Northern Ireland, “separatist and unionist” factions emerged, which continue to exist to this day. The separatists are predominantly Catholics who support the reunification of Northern Ireland with the Republic of Ireland. Unionists, on the other hand, are largely composed of Protestants and are in favor of remaining in the UK.
Such polarization in Northern Ireland, soon known as the Northern Ireland Troubles, led to violence that began in the late 1960s and lasted until a ceasefire was declared between the sides in 1994. The acts of violence almost escalated into a civil war, with hot conflicts between unionist paramilitary organizations and the Provisional Irish Republican Army.
In 1998, four years after the ceasefire of 1994, separatists and unionists signed the Good Friday Agreement. The Agreement established new institutions for cooperation between the United Kingdom, Northern Ireland and the Republic of Ireland creating a system of shared government in Northern Ireland. Thus, European single market, which was introduced in the European Union (EU) in 1993 but could not be implemented amidst the turmoil between the sides in Northern Ireland, was brought into practice between Northern Ireland and the Republic of Ireland.
As it may be recalled, the United Kingdom and the Republic of Ireland became members of the EU concurrently in 1973. As European single market entered into force in the EU, in 1993, and became operational between Northern Ireland and the Republic of Ireland, after the end of the turmoil in Northern Ireland, Northern Ireland was included in this common market as a member of the United Kingdom.
Since the introduction of the common market system, the border between Northern Ireland and the Republic of Ireland has been virtually invisible. Transit between the regions has been smooth, with no customs clearance. Many people living in Northern Ireland have been able to cross the Irish border to go to work every day, take vacations in the summer and visit relatives on special occasions. However, with the Brexit process that started in 2020, the UK’s departure from the EU, and thus from European single market, raised the issue of how the borders between two Ireland should be managed. Hence, the most challenging dispute of the Brexit process.
Leading up to Brexit, the issue was addressed for the first time by the then Prime Minister of the United Kingdom, Theresa May. According to the “Irish Backstop” submitted to parliament in 2019: if, at the end of the transition phase of Brexit, no agreement is reached on how the process in Northern Ireland will be managed, European single market legislation will remain in force until an agreement is finalized. The British Parliament rejected the bill three times and no consensus was reached. Indeed, this process led to May’s resignation.
Following May’s resignation, Boris Johnson became the Prime Minister of the United Kingdom and drafted the Northern Ireland Protocol, which paved the way for the approval of the Brexit Agreement in 2020. The Northern Ireland Protocol is designed to achieve the main objective of Brexit -the UK’s departure from the European single market- while respecting the exceptionalism of the border between Northern Ireland and the Republic of Ireland and the practices arising from it.
After leaving the EU, the UK will be a third country subject to customs controls in its trade with the EU. However, the border between the two Irish regions must remain open. A customs mechanism between Northern Ireland and the rest of the United Kingdom therefore needs to be put in place. The protocol requires all goods entering or likely to enter Northern Ireland to comply with the EU customs protocols. Goods that do not fulfill this requirement will not be subject to the corresponding customs protocols. Thus, the UK will be able to successfully exit the European single market.
The 2020 Northern Ireland Protocol is also coherent with the 1998 Good Friday Agreement. While the Good Friday Agreement does not include a clause to keep the border between Northern Ireland and the Republic of Ireland open, the spirit of the agreement envisages strengthening ties between separatists and unionists in Northern Ireland. Therefore, closing the border would be contrary to this very spirit.
On the other hand, the draft legislation (Northern Ireland Protocol Bill) presented by Johnson in 2022, to amend the terms of the Protocol, created tensions between London and Brussels. The draft provides for a dual regulatory regime allowing Northern Irish businesses to comply with either UK or EU standards for goods purchased in the UK and imported into Northern Ireland. Thus, there would be no need to establish a control mechanism to check whether goods coming from the UK into Northern Ireland cross the Irish border. However, Northern Ireland businesses strongly opposed the legislation, objecting that it would force them to opt between the UK and the EU. The EU, in turn, stated that the agreement was contrary to international law and urged Johnson to return to the Northern Ireland Protocol drafted in 2020.
Subsequently, in late 2022, Rishi Sunak became Prime Minister of the United Kingdom and a new resolution process began. On February 27, 2023, the UK Government announced its decision to halt the progress of the Northern Ireland Protocol Bill in the UK Parliament and its intention to allow it to lapse at the end of the current session.  This was followed on the same day by the announcement of the Windsor Framework, which sets out the customs regime for Northern Ireland under Brexit.
Under the Windsor Framework, two lanes will be created for goods entering the Northern Ireland borders from the UK. Green lane for goods that remain in Northern Ireland and red lane for goods that can be shipped to the EU, i.e. the Republic of Ireland. Control mechanisms and paperwork will be removed for products passing through the green lane. Products passing through the red lane will continue to be subject to control. This is intended to end the control mechanisms set out in the Northern Ireland Protocol, which in practice cover all goods that may enter the Republic of Ireland through Northern Ireland.
In addition, the Windsor Framework will introduce the “Stormont Brake”, whereby the Northern Ireland Assembly, which makes the laws in Northern Ireland, will be able to object to new EU rules, particularly in relation to the single market. However, such an objection shall not be available for “trivial reasons”, but shall be reserved only for “significantly different rules.” 
Opposition parties in the UK have announced that they will endorse Sunak’s bill. It is therefore considered virtually certain that the bill be adopted. Yet the reaction of the Democratic Unionist Party (DUP), Northern Ireland’s largest unionist party, to the bill is unclear. Having experienced the Northern Ireland Protocol Bill under the Johnson administration, the DUP refuse to take part in any customs protocol unless its concerns are addressed.  Therefore, the direction in which the Northern Ireland Question will evolve will largely depend on how the DUP and the Northern Irish approach the bill. All in all, it remains a matter of curiosity whether the Windsor Framework prepared by Sunak will be able to resolve the conflict.
 “UK MPs Vote Down Theresa May’s Brexit deal”, DW, https://www.dw.com/en/uk-mps-vote-down-theresa-mays-brexit-deal-by-391-to-242/a-47867378, (Date of Accession: 03.12.2022).
 “Implementing Brexit, The Northern Ireland Protocol”, Institute for Government, https://www.instituteforgovernment.org.uk/sites/default/files/publications/implementing-brexit-northern-ireland-protocol.pdf, (Date of Accession: 05.2020).
 “Reactions to the Northern Ireland Protocol Bill”, Indian Council of World Affairs, https://www.icwa.in/show_content.php?lang=1&level=3&ls_id=7583&lid=5062, (Date of Accession: 21.06.2022).
 “Political Declaration by the European Commission and the Government of the United Kingdom”, HM Government, https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1139420/Political_Declaration_by_the_European_Commission_and_the_Government_of_the_United_Kingdom.pdf, (Date of Accession: 27.02.2023).
 “Statement by President von der Leyen at the Joint Press Conference with UK Prime Minister Sunak”, European Commission, https://ec.europa.eu/commission/presscorner/detail/en/statement_23_1270, (Date of Accession: 27.02.2023).
 “Brexit: What is the Stormont Brake?”, BBC, https://www.bbc.com/news/uk-northern-ireland-64795902, (Date of Accession: 01.03.2023).
 “Windsor Framework: Sunak Urges Tory MPs Not to Create ‘Another Westminster Drama’ over Deal”, Irish Times, https://www.irishtimes.com/ireland/2023/02/28/windsor-framework-deal-will-make-positive-difference-to-people-in-northern-ireland-sunak-says/, (Date of Accession: 28.02.2023).
 “DUP ‘Won’t Be Pushed’ into Accepting UK-EU Deal on Northern Ireland-but Sees an Attractive Veto”, Politico, https://www.politico.eu/article/dup-wont-be-pushed-into-accepting-uk-eu-deal-on-northern-ireland-protocol-but-sees-an-attractive-veto/, (Date of Accession: 27.02.2023).