The negotiations between the United Kingdom and the remaining 27 nations of the European Union (EU27) have deadlocked over one topic: the backstop.
So what is the backstop? It’s designed as an insurance policy to one of the challenges of Brexit: the future of the Irish border.
Thanks to Britain’s Out vote, for the first time since 1973, the United Kingdom and Ireland will be in different trade and legal arrangements (both nations joined the then-European Community on the same day).
Although having a shared customs and regulatory framework did not prevent the development of a heavily militarised border between Northern Ireland and Ireland, it did help to end it. If, after Brexit, the United Kingdom wishes to have different regulations to the European Union, there will be checks when goods and other products move from one regulatory area to another.
Although most borders have a degree of checks and the EU’s land borders with Norway and Switzerland are relatively free of checks, the Irish border is the only border in the EU to have been the subject of a violent civil war over a still-contested constitutional settlement in living memory, so the border is more politically sensitive and border checks on it are more politically inflammatory.
Both the British and Irish governments have committed to avoid the creation of “physical infrastructure” on the Irish border (that means cameras and checkpoints and so on) and the aim is to do so through negotiating a free trade agreement with the European Union.
But trade talks sometimes break down, or stall, due to political differences between the negotiating countries or trouble at home for one or both sides. The Doha trade round of talks between the nations of the World Trade Organisation started in 2001, stalled in 2008 and has yet to restart. Although that is the most extreme example, neither government wants a situation in which a delay in the Brexit talks means the emergence of border infrastructure on the island of Ireland.
So the backstop is an insurance policy, that, in the event that the two sides cannot reach an agreement, Northern Ireland will remain within the European Union’s regulatory and customs arrangements indefinitely to prevent the emergence of a hard border.
But the political problem for Theresa May is that the Democratic Unionist Party, whose 10 MPs she needs the votes of to stay in office, opposes this arrangement as it would result in a border between Northern Ireland and the rest of the United Kingdom.
One solution would be for the whole of the United Kingdom to remain in the regulatory and customs orbit of the European Union indefinitely, but Conservative MPs oppose this because they fear that it would mean that the United Kingdom would remain within that orbit forever. But May cannot agree to a time-limited backstop as that would defeat the point: the whole objective is that it needs to insure that, whatever happens, and however long it takes to reach agreement, there will never be a hard border on the island of Ireland.
With none of the political players able to reach an agreement, it looks likely that the issue may cause the United Kingdom to leave without a deal.