But in our submission, my Lords, my Lady, the UK Government's contentions on the extent of its prerogative power are, with respect, cavalier, perhaps in this context with both a small C and a large C; in respect, my Lords, my Lady, of the effect which the cessation of the EU treaties will have on the delicately balanced constitutional settlement in Northern Ireland.
I heard my learned friend Mr Eadie to say in his submissions that real clarity is required in a statute before the constitutional balance is upset. His submission, of course, was addressed to what he would suggest is the removal by statute of a well-established prerogative power, and on that, we agree with the claimants in Miller that that is to look at the matter from the wrong end of the telescope.
But my Lords, my Lady, Mr Eadie is right to say, where a constitutional balance is being upset, clear statutory authority is required. And where what we have called a pillar of the constitution set out in the Northern Ireland Act is being removed or hollowed out, that can only be done by an act of Parliament.
My Lords, my Lady, the third strand of issue one, this is an argument which is peculiar to the circumstances of Northern Ireland, it arises from the proves of the Northern Ireland Act giving rise to the Belfast agreement, which require -- sorry, giving effect to the Belfast agreement which require north/south cooperation in the context clearly, we say, of continued EU membership.
The submission is that continued membership of the EU is an integral part of the scheme of the Act, on this basis, as well as the two bases just mentioned, and the royal prerogative cannot be used in a manner inconsistent with that statutory purpose.
As the court will hopefully have seen from our written case, the British-Irish agreement, which we accept is unenforceable as a matter of domestic law but which forms the interpretative backdrop to the Northern Ireland Act, expressly envisaged that the UK and the Republic of Ireland would develop close cooperation between their countries as partners in the European Union. Your Lordships, and your Ladyship, will find that at MS 20373.
That partnership, we say, is necessary because the Belfast agreement not only envisaged but required, as part of the north/south cooperation it established, the implementation of EU policies and programmes on an all-Ireland basis and a cross-border basis, or at the very least the possibility of such implementation.
Now, we say that that is a core part of the scheme of the Northern Ireland Act, and the purpose for which the north/south machinery has been established in part 5.
My Lords, my Lady, the kernel of our case on that point is set out in paragraphs 46 to 51 of our written case. It may be helpful if the court would turn briefly to strand two of the Belfast agreement. Your Lordships will find that in Northern Ireland authorities, volume 1, tab 14, beginning at MS 20354.