To say the backstop is constitutionally impossible is a self-defeating lie being propagated by leavers and remainers who want the deal to fail for their own reasons. 1/
2/ Most obviously it was not impossible when the Prime Minister agreed to it in December and subsequently in March.
3/ There's already differentiation between Northern Ireland and the UK on abortion, taxes etc. What that differentiation should be can be a subject for debate.
4/ But it shouldn't be determined unilaterally by the DUP who only represent part of one community in NI, and at the cost of the national interest of the UK as a whole.
5/ In this case elevating this to a constitutional principle and risking no deal is the grave threat to the Union, because it's disastrous consequences would hand a decisive argument to Scottish and Irish nationalists - the ship is sinking: to the lifeboats!
6/ There is a view doing the rounds that Ireland will refuse to put up a border if there is no deal (there's also a view that the border is practically not sealable - this is untrue - it was closed during foot and mouth - doing so presents a rather a very hard political problem)
7/ Though Ireland maintains for public consumption that a border must be avoided, it knows it will be required by EU membership to do so, and blaming "British intransigence" will provide them the political cover amid emergency no deal conditions to do so.
8/ Serious Irish opinion knows this to be the case. Ireland is not strong enough to force the EU to abandon its primary objective, which is maintaining the integrity of the Single Market.
9/ The rest of the EU see offering the backstop as a *concession to Ireland* because of NI's history and small size.
10/ The EU overreached by trying to keep NI inside the full SM and CU - though popular in NI - the transfer to Scotland made it impossible for London to accept.
11/ The dedramatised backstop, involving few checks at ports however does not read across to Scotland: because Scotland has a land border. It would replicate the disruption of an Irish land border, but in Great Britain
12/ The SNP might welcome such disruption but it's not something a Unionist party could want.
13/ Which brings us back to the false constitutional principle. A new group of Leninist remainers is now promoting this because they want the deal to fail because they think it gives them a chance for a referendum to revoke Brexit
14/ So now both they and the hard brexiteers have United in presenting the dedramatised version of the backstop as an assault on the constitution.
15/ The consequences of this could well sink the deal, and provoke an unfathomably unpredictable political crisis whose most likely outcome is one no Unionist whether Tory Remainer or Brexiteer would want: a government led by Jeremy Corbyn.
