NEWRY, NORTHERN IRELAND - MARCH 29: A former customs guard hut directly situated on the north south Irish border stands disused as Brexit is triggered on March 29, 2017 in Newry, Northern Ireland. The northern Irish border is the United Kingdom’s only land border with the rest of Europe. British Prime Minister Theresa May will address the Houses of Parliament later today as Article 50 is triggered and the process that will take Britain out of the European Union will begin. (Photo by Charles McQuillan/Getty Images)

The boundary between the Republic of Ireland and Northern Ireland, long the scene of tense checkpoints and violent protest, is once again caught up in a bitter division. When British and European Union leaders carry out the split -- Brexit -- that British voters ordered up, the border between Ireland’s north and south will be the only land crossing between the two jurisdictions. The need to keep the border invisible, so that people and goods are free to cross back and forth, has shaped the Brexit talks and led to an impasse over a controversial solution known as the backstop.

1. Why is the Irish border such a problem?

Both sides agree that no physical border can be allowed to emerge between Northern Ireland, which is part of the U.K., and the Republic of Ireland, which remains in the EU. That’s because a reintroduction of customs controls would impose delays and costs on cross-border trade that’s worth more than 3 billion euros ($3.5 billion) a year. Moreover, a return to checkpoints and watchtowers could endanger the region’s hard-won peace.

2. What is the backstop?

Simply put, it’s a guarantee that the border remains open regardless of the outcome of trade negotiations on the future EU-U.K. relationship, which have yet to begin. The U.K. has pledged to remain in a customs union with the EU, abiding by the bloc’s trade and tariff policies, after a transition period ends, unless and until the two sides agree on some better arrangement. Under the backstop, Northern Ireland would be tied more closely to the EU’s rules and standards than the rest of the U.K.

3. What’s the problem with the backstop?

Many U.K. lawmakers say the backstop risks binding the U.K. to EU rules forever, especially since the U.K. cannot exit it unilaterally. They argue that Prime Minister Theresa May caved in to the EU and betrayed the electorate’s call to regain sovereignty while treating Northern Ireland differently from the rest of the country. To be sure, Northern Ireland already diverges from the rest of the U.K. on some issues, including its ban on abortion and its rules on animal health. The EU has offered written assurances that the backstop would only be temporary, and that the bloc doesn’t want it ever to come into effect. But that probably won’t be enough to bring U.K. lawmakers onside.

4. Could there be a better solution?

There’s been discussion about whether a high-tech border, using cameras, drones and a system for pre-clearing goods, could provide a solution. As of now, few on either side think such technology exists. More relevantly, the U.K. hopes to eventually reach such a deep and wide-ranging free-trade deal with the EU that checks on the Irish border become unnecessary. Negotiating that trade deal, however, is expected to take years.

5. What is the border like now?

It meanders through countryside for some 310 miles (500 kilometers), dividing rivers, fields and even some houses; a change in road signs and accepted currency is pretty much the only indication that a person has moved into a different jurisdiction. The island was partitioned in 1921 as part of a peace agreement between the U.K. government and Irish rebels seeking independence. As part of the deal, Northern Ireland, where the population is majority Protestant, remained part of the U.K. with England, Scotland and Wales. The mostly Catholic southern part of the island became the Irish Free State and gained full independence in 1948.

6. How does the open border work?

Businesses are able to work across the entire island. Diageo Plc, the maker of Guinness and other beverages, has brewing operations on both sides of the border and sends its trucks across about 18,000 times a year. Similarly, the free movement of horses has helped make Ireland a world leader in the bloodstock industry, which includes racing and breeding, adding about 1 billion euros to the economy. As for humans, an estimated 30,000 people pass through 300 different crossings every day.

7. What does this fight mean to Ireland?

At the very least, it brings back bad memories. The border has been a symbol of British rule almost since it was created, with customs and later military checkpoints positioned at crossings over the course of decades. The Irish Republican Army, which wants a united Ireland, waged a bombing campaign along the border in the 1950s and 1960s. Violence between republican and unionist paramilitary groups claimed about 3,500 lives from the 1970s onward before the arrival of the European single market and a peace accord in the 1990s, when border controls largely melted away.

8. Could a hard border lead to the return of violence?

Customs and security checks would likely hurt the economy on both sides of the border, and perhaps offer a daily reminder of British rule of Northern Ireland. While the province has been at peace for almost two decades, Martin McGuinness, Northern Ireland’s former deputy leader, warned a year before his death in 2017 that the reintroduction of a border following Brexit could aid those who oppose the region’s peace process. Other politicians argue that peace is now so deeply rooted that it would take more than a few border posts to disrupt the island.

To contact the reporter on this story: Peter Flanagan in Dublin at

To contact the editors responsible for this story: Dara Doyle at, Laurence Arnold

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