Anti-Brexit campaigners protest outside government buildings in Dublin.Clodagh Kilcoyne / Reuters

On at least one crucial issue when it comes to Brexit, Boris Johnson has a point, though not entirely for the reasons many of his supporters claim.

The new British prime minister has threatened to take Britain out of the European Union on October 31, the deadline by which the country must exit the bloc, without a deal unless a contentious clause is removed wholesale from the exit package negotiated by his predecessor, Theresa May. This clause, known as the backstop, aims to ensure that no matter what, the border remains open between Northern Ireland, which is part of the United Kingdom and thus set to leave the EU, and the Republic of Ireland, a separate EU member state.

This clause became the focus of Brexit supporters’ opposition to May’s negotiated withdrawal agreement, ensuring that she would never get it passed by Parliament, and thus leading to her resignation. Johnson has claimed that the backstop is “antidemocratic” and something no British government could ever accept. His opening position dramatically increases the chances of Britain leaving the bloc without a deal this autumn, sparking an economic and diplomatic crisis at the heart of the Western alliance. Whereas May’s team sought to downplay any concerns over the backstop, the Johnson administration has flipped that strategy on its head, seeking to highlight flaws in an attempt to delegitimize the backstop.

So what is the backstop, and why has it galvanized Brexiteer anger? On its face, the backstop is a legal device, largely drawn up in Brussels but significantly tweaked at London’s request, to ensure that the border on the island of Ireland remains free of physical infrastructure checking the people and goods that cross back and forth each day (as it has been for two decades, and in contrast to most international borders outside the EU, such as the one between the United States and Canada).

It does so in two main ways: First, by ensuring that Northern Ireland (and not the U.K. as a whole) continues to be bound by EU regulations on food, farming, and industrial goods, so that products in these areas don’t have to be checked moving across the land border. Instead, they will be checked at the internal U.K. sea border with mainland Britain. Second, the backstop keeps the whole of the U.K. in the EU’s customs zone, meaning goods moving within the country or into Ireland are not subject to tariffs.

At its heart, however, the backstop is no mere technical fix—it poses fundamental questions of law and sovereignty, national identity and representation. The backstop is a policy proposal designed to maintain the status quo in Northern Ireland that has kept the peace for 20 years, but its critics claim that it inadvertently risks untipping that same careful balance.

Do those critics have a point? Even some key figures in May’s administration, including two senior government officials I spoke with, who asked not to be identified, admitted that there are fundamental problems with the backstop that have not been addressed. Here are five of them:

Democracy

Johnson’s attack on the backstop correctly identifies one of its most significant flaws: its patent democratic deficit.

Under the backstop’s provisions, Northern Ireland will be bound by EU law, without its ongoing democratic consent: No elected officials from Northern Ireland will be able to vote on new EU laws that will apply in Northern Ireland. It is regulation without representation. Whether this is a price worth paying for stability in Northern Ireland and an orderly Brexit is a different question than whether it is democratic, which it is not.

Where Johnson’s supporters are on far less solid ground is with the claim that the backstop is antidemocratic for the U.K. as a whole. Their argument goes that because, under the backstop, the U.K. remains in the EU’s customs territory, this amounts to staying in the EU, thereby undermining the 2016 referendum result. It does not. By definition, the U.K. will have left the EU, even if some of the EU’s laws continue to apply to part of the U.K’s territory.

Power-sharing

Irish Prime Minister Leo Varadkar and others have claimed that the backstop has public support in Northern Ireland, which therefore gives it democratic legitimacy. Varadkar cites the elections to the European Parliament in May, which saw explicitly pro-backstop parties win 57 percent of the vote.

Yet this is not how politics works in Northern Ireland under the terms of the Good Friday Agreement. The central achievement of the 1998 peace deal, which brought the Troubles to an end—and which the backstop is supposed to protect—was the trade-off by which Northern Ireland would remain part of the U.K. until a majority in Northern Ireland said otherwise. In exchange, direct rule from London was brought to an end and all sides agreed that power would be shared between nationalists, who support unifying Northern Ireland with the Republic of Ireland, and unionists, who support staying part of the United Kingdom. In other words, majority rule, which had governed Northern Ireland until the Troubles, was replaced.

Citing simple majority support for the backstop now misses the point about how Northern Ireland functions in the post–Good Friday Agreement era: Decisions must be agreed on by both sides in there. How many U.S. representatives now warning about jeopardizing the Good Friday Agreement—or indeed, British or EU politicians opining on the matter—understand this core achievement of the peace agreement remains unclear.

What Johnson’s supporters are less keen to point out, however, is that this logic could also easily apply to any decision to take Northern Ireland out of the EU with no deal (or at all), something fiercely opposed by the nationalist community and a majority of voters in Northern Ireland—56 percent of people there supported remaining in the EU in the 2016 referendum. Brexit, in and of itself, is a form of U.K. majoritarianism imposed on Northern Ireland. The irony is, if a simple majority is unhappy about this and decides it wants to join the Republic of Ireland, the Good Friday Agreement gives it this right. This is the inherent gamble of Northern Ireland’s unionists.

Partition

Nothing in domestic or international law forbids border checks between the U.K. and Ireland. Nothing in the Good Friday Agreement prohibits economic checks taking place between the two sovereign states that jut up against each other on the island of Ireland. The question of erecting physical infrastructure along their border is not a legal one, but a political one rooted in history, identity, and violence. Indeed, the Good Friday Agreement reaffirmed Northern Ireland’s legitimate constitutional place in the U.K. and, by extension, the border that exists on the island of Ireland.

One of the many leaps of faith that ended the Troubles was the Republican movement—the hard-line wing of Irish nationalism that sought to reunify Ireland through violence—agreeing to work within the existing constitutional structures to achieve Irish unity, implicitly accepting the border as it had existed since the island was partitioned into two separate jurisdictions in 1921. (For much of the Republican movement’s history, as a matter of principle, Sinn Féin, its main party in Northern Ireland fighting for Irish unification, refused to stand candidates for elections in either Belfast or Dublin, because to do so—it believed—was inherently partitionist.)

The corollary is that for many unionists, it is one thing for the U.K. and Ireland to agree that there should be no physical controls policing the border, something London has committed to. But many senior unionists have voiced fury that, by agreeing to the backstop and its conditions of Northern Ireland being bound by EU and not U.K. law, the May government appeared to accept that Northern Ireland and the Republic of Ireland could not even be two distinct jurisdictions in principle. In effect, in their view, May had traded away that principle in response to threats of violence against anything that polices the border.

This gets to Brexit’s most basic question: Whose law applies in whose territory? The backstop means that even after Britain leaves the EU, the bloc’s law extends beyond its borders into another jurisdiction.

Practicalities

According to one of the May-administration officials I spoke with, there are two main practical problems on top of the problems of principle.

The first centers around the scale and scope of the checks that will be required under the terms of the backstop. These checks, on industrial goods, animals, and agricultural produce, will be carried out within the U.K., at the sea border between the British mainland and Northern Ireland, so as to avoid them taking place at the land border with the Republic of Ireland.

In this scenario, to move industrial goods from, say, London to Belfast, businesses will have to produce a document (a U.K. movement certificate) to prove the goods’ origin, an onerous new requirement on both companies and the authorities, in the view of its critics. But not as onerous as that for food, which will be checked in full to ensure that they are properly documented, and undergo physical inspection rates of up to 100 percent. Remember: This is for produce moving within the United Kingdom.

What frustrated the May government was the fact that the scale of the proposed checks was far greater than that of checks on goods from some non-EU countries, such as New Zealand, which struck a “veterinary agreement” with Brussels that means only 1 to 10 percent of its agrifood exports to the EU are physically checked (they still have documentation checks).

The second practical area of concern is that the backstop includes Northern Ireland in the EU’s value-added-tax (VAT) zone, which means that if the rest of the U.K. overhauls its VAT system, a financial gulf would be created within the country. Under EU rules, no country can lower its standard VAT rate below 15 percent. The VAT rate in the U.K. is currently 20 percent, but if the government wanted to move outside the EU band, it could not apply its new rules to Northern Ireland.

Leverage

Finally, and perhaps the core problem of the backstop, is that it is indefinite. Many of the above problems could be swallowed, its critics say, if it were just a stopgap, and legally limited in how long it would last. Critics argue that it completely untips the balance in what comes after Brexit: negotiations over the future relationship between Britain and the EU, and the arrangement that replaces the backstop.

At its crudest, why would the Republic of Ireland agree to anything less than the backstop, which indefinitely binds Northern Ireland to the same rules that apply south of the border? To unionists, whose priority is to maintain the sovereignty of U.K. law in Northern Ireland, unless the Republic of Ireland knows that the backstop is temporary, it will never engage in efforts to find a solution that works for both communities in Northern Ireland. The trust has gone.

It is for this reason, Varadkar’s more thoughtful critics in London and Belfast suggest, the Irish government should have accepted a time limit on the backstop when May was prime minister. This would have bought both sides time to find a solution acceptable to all. Now Johnson has said that even a time limit is not enough, and that the backstop has to be removed entirely.

None of this means the U.K. government should reject the backstop. The decision for Johnson, and Britain’s Parliament, is a political one that must be balanced against the very real problems of not accepting the backstop.

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