Brexit’s Stickiest Point: The Irish Backstop

The Irish backstop is an attempt to avoid renewed instability in Northern Ireland, but opponents say it could keep the United Kingdom trapped in the European Union’s customs union forever. The dispute could determine the future of Brexit.

What’s happening?

As the March 29 deadline to leave the European Union approaches, the UK Parliament has not yet passed Prime Minister Theresa May’s deal with the EU. May’s biggest obstacle has been opposition from within her own coalition; many pro-Brexit members of Parliament (MPs) worry that the agreement’s so-called Irish backstop will keep the UK enmeshed in the EU.

What is the backstop?

The backstop is an effort to avoid a hard border between the Republic of Ireland and Northern Ireland. Northern Ireland is the only part of the UK that shares a land border with another country.

There are good reasons to worry about the Irish border. It was at the heart of the Troubles, a thirty-year period of sectarian violence that ended with the 1998 Good Friday Agreement. It was once heavily militarized, and militias targeted the border checkpoints patrolled by British soldiers. The peace process was able to all but abolish visible signs of the border, because both Northern Ireland and the Republic of Ireland were part of the EU customs union and single market, which provide for free movement of goods and people.

Brexit means Northern Ireland will leave the EU, bringing back the border. Violence could return along with it, especially if the border is reimposed suddenly. May agreed to the backstop to make sure that Northern Ireland remains in an arrangement with the EU akin to the single market until another trade deal is in place. If the backstop comes into force, Northern Ireland will continue to follow most of the single market’s rules. Mainland Great Britain will remain in a customs union and therefore have to keep following many EU regulations.

Meanwhile, under May’s plan, the UK and EU would continue negotiating a permanent arrangement. The UK hopes that technological advancements, such as a virtual customs system, could eventually sidestep the need for border checks altogether. It’s a hope the EU sees as unrealistic.

Why do Brexiteers oppose it?

There are two main arguments against the backstop.

First, Brexiteers worry it could become permanent, forcing the UK to follow the bloc’s rules without getting any say in making them. For MPs who want to take back control of trade and immigration, that’s untenable. They won’t support May’s deal without an explicit end date for the backstop, something the EU has flatly rejected.

Second, Northern Ireland’s unionists, who back a strong union with London, worry that the backstop could create a “two speed” UK if Northern Ireland remains subject to more EU regulations than the rest of the UK. An implicit border in the Irish Sea, they say, would isolate Northern Ireland. This argument carries particular weight because May’s parliamentary coalition relies on ten MPs from Northern Ireland’s main unionist party.

So what are the options?

Parliament has already voted down May's deal twice, both times by historic margins. With the deadline approaching, May will have to ask the EU for an extension, which requires the unanimous support of all twenty-seven other members. If the EU agrees, some believe the Labour Party will then team up with moderate Tories to pass a Brexit deal that permanently keeps the entire UK in the EU single market, resolving the border issue. If the EU doesn’t agree, a hard Brexit, including Irish border checks, could become a reality.

More radical eventualities are also on the table: Northern Irish nationalists have called for a referendum on whether Northern Ireland, whose residents voted against Brexit in the 2016 referendum, should unify with the Republic of Ireland. In that case, the border issue could end up threatening the United Kingdom itself.