The Democratic Unionists have rejected fresh Government assurances on the Irish border backstop as “cosmetic and meaningless”.
Deputy leader Nigel Dodds said the series of commitments from Downing Street had not altered his party’s strong opposition to Theresa May’s Brexit deal.
In a 13-page paper published on Wednesday morning, the Government pledged to enact a raft of new domestic laws to assuage concerns that Northern Ireland would be treated differently to the UK if the backstop was ever enacted.
The backstop, which would come into effect if a wider UK-EU trade deal fails to materialise by the end of the Brexit Implementation Period, would see Northern Ireland continue to adhere to a number of EU rules.
It is designed to maintain a free-flowing Irish border regardless of the outworking of Brexit, but the DUP and other Brexiteers claim it would undermine the constitutional integrity of the UK by creating barriers between Northern Ireland and Great Britain.
The Government has now pledged to give the currently defunct Northern Ireland Assembly a “strong role” if the contentious backstop is ever triggered.
It has offered a legally binding commitment to “consult” with Stormont before deciding to either enter the backstop or ask for an extension of the Implementation Period, which will currently expire at the end of 2020.
However, the ultimate decision would be taken by Parliament.
If the backstop does come into effect, the Government said the Stormont Assembly and Executive would then be given a “strong” oversight role in its operation.
If the EU proposed changing any laws that impacted the operating of the backstop, the Government said it would have to consent to such a measure applying to Northern Ireland. Downing Street has now committed to seek the agreement of the Assembly for any such changes.
Criticising the Government proposals, Mr Dodds insisted that any amendments to domestic UK law would always be trumped by the provisions of the Withdrawal Agreement, because it was an international treaty.
“We reject the backstop and have previously, and consistently, indicated we will not support an internationally legally binding withdrawal agreement that contains its provisions,” he said.
“Such an international treaty supersedes and overrides any contrary domestic legal provisions.”
He added: “The Assembly would not be able to override UK international legal obligations as the backstop provisions would be in the treaty.”
Mr Dodds highlighted that the EU-UK Joint Report on Brexit in December 2017 contained a commitment that the Stormont Assembly would ultimately decide if specific Northern Ireland arrangements would be required.
“Consultation cannot replace the Assembly determining these matters,” he added.
“Furthermore, it is clear that under these proposals providing a law for a mandatory process of consultation with the Assembly on whether to bring the backstop into effect would ultimately have no bearing on the decisions to be taken by Parliament.
“Were we to find the backstop being brought into effect then in such circumstances there would be no exit mechanism from the backstop and consequently these series of measures outlined by the Government would not be sufficient to deal with the major and significant flaws of an internationally binding backstop arrangement.”
Sinn Fein has also rejected the proposal to hand the Assembly a role determining the future functioning of the backstop, claiming it would hand the DUP a “veto”.
The Assembly has been in cold storage for almost two years following the collapse of the last Sinn Fein/DUP-led powersharing administration.
If it was to be resurrected, the institution’s voting structures mean large groupings of unionist or nationalist Assembly members can effectively wield a veto – using a device called the ‘petition of concern’ – even if a majority of other MLAs are in favour of a particular course of action.
Ahead of a visit to Brussels on Wednesday, Sinn Fein vice president Michelle O’Neill stressed that a majority of MLAs in Northern Ireland were Remainers.
“It’s important to put in context that the majority of elected representatives are opposed to Brexit. So in terms of giving the Assembly and the DUP a veto on any of those things in the future, that will not be acceptable to Sinn Fein and I dare say it’ll not be acceptable to the other (pro-Remain) parties,” she said at Stormont on Tuesday.