A government legal team has argued in the Supreme Court that the Northern Ireland Protocol does not change the constitutional position of Northern Ireland within the UK.
It comes on the final day of a legal challenge to the lawfulness of the protocol that is being heard at the UK's highest court.
The protocol was struck by the EU and UK to prevent a hardening of the border between NI and the Republic. It has, however, created a border down the Irish Sea.
A legal team for the coalition of unionists who took the case to the UK's highest court argue Northern Ireland's constitutional position has significantly changed because of the protocol.
But Tony McGleenan KC for the government told the court that Parliament had known what it was doing.
He said that there was nothing “duplicitous or sinister" about the Withdrawal Agreement that brought the protocol info effect.
On Wednesday John Larkin KC, for those who took the case, said "Northern Ireland has sufficiently, in substance, ceased to be part of the UK" because it is now “a separate customs territory".
That was totally rejected by the Government's legal team who argued that parts of the Act of Union have been "disapplied" by the Protocol, not breached or repealed.
Mr Tony McGleenan KC said the arguments of those who took this case were "seriously overplayed".
"The idea that there has been a de facto termination of the union is not a tenable proposition. It's a modest disapplication subject to a democratic vote."
The panel of Supreme Court justices will now consider the arguments and make their ruling in the new year.
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