Britain could therefore be outside the European Union, with no voice in shaping its rules, but remain closely tied to the bloc indefinitely. To Mrs. May’s hard-line, pro-Brexit colleagues, that is a nightmare scenario that could leave Britain permanently powerless to determine its own trade destiny.
The prime minister could ignore the pro-Brexit factions in her party and cut a deal with the Labour Party for a “soft” Brexit that would, at minimum, leave Britain in the customs union. But that would risk alienating those who voted in the referendum to leave, and it would risk tearing the Conservatives apart, an outcome that many believe is Mrs. May’s greatest fear.
European officials have suggested that Britain could largely avoid the single market standards by having only Northern Ireland abide by those listed in the backstop, while a different set of rules could be adopted for the rest of the country. British lawmakers have rejected that out of hand because they say that it would create a virtual border in the Irish Sea, cutting off Northern Ireland from the rest of the United Kingdom and moving it closer to unification with the Republic of Ireland.
Mrs. May argues that the backstop might never go into effect, and that, even if it did, it would not be in place for long. Her government envisions a future system that would allow customs and standards checks without actually stopping and inspecting trucks or people at the Irish border — technology that does not yet exist.
What happens next?
This month, Parliament rejected Mrs. May’s agreement by a crushing margin, 432 to 202. Primarily because of the backstop, 118 of the 317 lawmakers from her Conservative Party voted against it, as did all 10 of the Democratic Unionists of Northern Ireland, whose support Mrs. May relies upon for her parliamentary majority.
On Tuesday, Parliament voted to direct the prime minister to return to European negotiators and demand an expiration date to the backstop, or a clause that would allow Britain to withdraw from it without the bloc’s approval.
But Brussels has insisted that it will not budge, and even if it made such a concession, it is not clear that a change would ensure passage of Mrs. May’s deal in the British Parliament.