The Irish backstop would continue to apply “unless and until it is superseded” by a subsequent agreement, government legal advice on Brexit has confirmed.
A document published by the UK Government in response to a demand from MPs to see the full legal advice on Brexit confirms the UK would need to stay within the backstop, tying it to EU trade rules.
It also says the UK faces making additional payments to Brussels if the Brexit implementation period is extended.
The document will do little to satisfy Brexiteers who oppose the Prime Minister’s deal on the basis it will undermine the UK’s sovereignty.
Publication of the legal paper came as Theresa May’s chief Brexit adviser told MPs the Northern Ireland border backstop was a “slightly uncomfortable necessity” for both the UK and the European Union.
Olly Robbins told the Exiting the European Union Committee the fallback plan agreed with Brussels was “not the future relationship that either the UK or the EU wants to have with one another”.
Mr Robbins said: “It is an uncomfortable position for both sides and the reality ... is that there is not a withdrawal agreement without a backstop.
“That reflects also, as I’ve said to this committee before, ministers’ commitments to Northern Ireland and to avoid a hard border on the island of Ireland, rather than being something imposed upon us.
“So it is a necessity and a slightly uncomfortable necessity for both sides.”
Asked if the Government had drafted a clause for the withdrawal agreement that would have allowed the UK to opt out of the backstop unilaterally, Mr Robbins said: “Ministers asked us to look at a whole range of options for how to bring the backstop to an end and so we did.
“And the Prime Minister and other ministers tested some of those out on European partners.
“But what we went into the negotiation with in the end was a text that delivered the termination clause very much as it is laid out there.”
The government’s 43-page Legal Position On The Withdrawal Agreement was released this afternoon in response to pressure from MPs.
The document states: “The main provisions of the protocol come into force from the end of the implementation period … in the event that a subsequent agreement is not in place by then, and the protocol will continue to apply unless and until it is superseded, in whole in or part, by a subsequent agreement establishing alternative arrangements.”
But if the implementation period is extended then the backstop will not apply until after the end of that period, the paper states.
Under the terms of the withdrawal agreement, the transition phase is due to run until the end of December 2020, but can be extended by up to two years if both sides agree.
The advice says that discussions on any extension would involve “reaching further agreement on the UK’s financial contribution”.