I am grateful.
I note the court also has a timetable as to the submissions that will be made, and I know that all counsel will do their best to keep to that.
There are, if I may, two points I wish to make at the outset on which I believe all parties are agreed, and they follow from what my Lord President has just said. The first is that this is a case of great constitutional significance in which there is understandable and legitimate interest, both inside and outside this courtroom and, second, in light of what followed the divisional court's judgment, it should be said with clarity that this is a case which the claimants brought perfectly properly and which it is now perfectly proper for this court to decide.
That is so because there is a clear question of law before the court, namely, whether the Government has the legal power to give notice under Article 50 of the Treaty on European Union to begin negotiations for the UK's withdrawal from the EU, or whether further specific legislative authority is required to do so.
That, we submit, is a clear question. But it is not a narrow one. It raises issues going to the very heart of our constitutional settlement. The question arises, of course, because the United Kingdom is about to leave the European Union, as a result of a course of events which I submit is worth restating.
At the last general election, the Government was elected with a manifesto commitment to hold an in/out referendum on the UK's membership of the EU. Parliament provided for that referendum through the European Union Referendum Act of 2015. The referendum was conducted, we say, in the universal expectation, including in Parliament, that the Government would implement its result. As the foreign secretary told the House of Commons at second reading of the bill, and I quote:
"This is a simple but vital piece of legislation. It has one clear purpose: to deliver on our promise to give the British people the final say on our EU membership in an in/out referendum by the end of 2017."
My Lords, I don't propose to ask you to turn to that, but if you wish to find it, it is at volume 18 of the bundles, tab 203.
A majority of those who voted in the referendum wanted the UK to leave the European Union, and Article 50 provides the specific legal mechanism to begin doing so.
Now, my Lords, the divisional court treated all of that as legally irrelevant and concluded that the process could not lawfully be begun by the Government using prerogative powers but only by further legislation in Parliament. We say, respectfully, that the divisional court was wrong about that. We say that use of the prerogative in these circumstances would not only be lawful but fully supported by our constitutional settlement, in line with parliamentary sovereignty and in accordance with legitimate public expectations.
So in opening this appeal, I make three submissions by way of introduction to our case from this fundamental constitutional perspective. My learned friend Mr Eadie will then develop our case and the Advocate General for Scotland will deal with the devolution and other issues raised in relation to the Scottish, Northern Irish and Welsh jurisdictions.
My three submissions are these. First, that the foreign affairs prerogative is not an ancient relic but a contemporary necessity. Including the powers to make and withdraw from treaties, it is a fundamental pillar of our constitution as a sovereign state and it is essential to the effective conduct of public business.
Second, that the prerogative operates as part of a dualist system, including in the EU context.
Third, that the prerogative operates wholly in accordance with parliamentary sovereignty. Parliament has a clear understanding of the constitutional function and usefulness of these powers, and where it chooses to limit them, it does so carefully and specifically.
So, my first submission is on the importance of the foreign affairs prerogative. The powers to make and unmake treaties, conduct diplomacy and take part in multilateral decision-making do not, we say, reside with the executive as unfinished business or as a result of historical oversight, but because there are good constitutional and practical reasons why they should. The need for the Government to maintain control over strategy, policy and operational matters in conducting our bilateral or multilateral international relationships is, we say, clear and compelling.
That has long been true. I want to read from Blackstone's Commentaries on this matter. Again, I don't invite your Lordships to turn it up for these purposes, but it can be found at volume 27 of the bundle at tab 329.
At that point, describing the foreign affairs prerogative as, and I quote "wisely placed in a single hand by the British constitution for the sake of unanimity, strength and dispatch". It goes on to say, and again I quote:
"With regard to foreign concerns, the King is the delegate or representative of his people. It is impossible that individuals of a state in their collective capacity can transact the affairs of that state with another community equally numerous as themselves. Unanimity must be wanting to their measures and strength to the execution of their counsels."
My Lords, we submit that remains the case. Ours is not the only constitutional system where this is accepted. Other common law jurisdictions recognise similar power for their own governance. In the United States, in Canada and in Australia, the executive branch holds the power to make and unmake treaties, and these are powers that are used often.
In the last 12 months the Government has signed 31 new treaties on a range of subjects, including transport, mutual legal assistance, defence, prisoner transfer and the environment.
They have been used too by the Government in playing our full part as a member state of the European Union, including in the process of shaping the development of the EU legal order, and all the ebb and flow of EU law rights and obligations that that entails.
The Government has been doing this since 1972 by participating in Council of Ministers' decision-making as well as in the day-to-day transaction of Commission negotiations in Brussels, and diplomatically with other member states. All this, we say, is done using prerogative powers and with Parliament's acceptance.
My second submission is that all this is done as part of the functioning of the UK's dualist legal system. Mr Eadie will develop this submission in more detail, but I want to give the court a flavour of it at this stage.
It is common ground that treaties are not self-executing. Prerogative actions of the Government on the international law plane on the one hand, and on the other, Parliament giving effect as necessary to rights and obligations on the domestic plane are legally and constitutionally separate. The EU legal order, we say, is not an exception to that dualist system; it is a clear example of it.
To implement the UK's original treaty obligations, the 1972 European Communities Act provided for a conduit for the inflow of the EU legal order; that was its purpose. But the existence of a mechanism such as the 1972 Act for implementing the consequences of EU membership in domestic law has no bearing, we say, in a dualist system on the existence or use of the foreign affairs prerogative to remove the EU legal order at international level.
That is at least in part because the 1972 Act does not and cannot create EU rights and obligations. It says so in terms, and you will be taken to the relevant language. EU rights and obligations are negotiated and agreed by Government and are created and arise on the international law plane.
Doing so we say involves and has always involved the use of prerogative powers. The 1972 Act provides for the rights and obligations from time to time existing on the international plane to be part of domestic law. Those rights and obligations in domestic law are therefore inherently liable to change, to be expanded, shrunk or withdrawn altogether by action at the EU level.
An action which has that effect, an effect which can include the removal of previously existing treaty-dependent rights, is action taken in the exercise of prerogative powers. That, we say, is the logical consequence of the conduit mechanism which Parliament brought into being with the 1972 Act.
Which brings me to my third submission. Parliament is sovereign. Parliament can, if it chooses, legislate to limit the prerogative and it has done so, but where it has done so, it has done it sparingly and explicitly, conscious, as it has always been, of the need for prerogative powers and the effective conduct of Government business.
So Parliament has considered carefully the proper extent of its involvement in the making of treaties. The provisions in part 2 of the Constitutional Reform and Governance Act 2010 were the culmination of a lengthy process of dialogue between Parliament and the executive and of wider public consultation.
That Act introduced a series of controls in relation to the ratification of treaties, but it did not introduce a requirement for primary legislative authority, nor did it seek to control the prerogative power to make or significantly to withdraw from treaties.
Parliament has also considered, with particular care and in detail, what the balance of legislation and prerogative power should be in the specific context of the European Union. Parliament has done so in a series of acts, beginning with the 1972 European Communities Act and ending with the 2015 European Union Referendum Act. We will take you to the details of that sequence.
But I would make two points at this stage: first, there is nothing in the wording of the European Communities Act, or indeed in the later legislation to which Mr Eadie will take you, to inhibit withdrawal from the European Union treaties or subject it to a requirement of prior legislative authority. That therefore remains to be done by the Government in exercise of well-established prerogative powers. It is not as though Parliament has been short of opportunities to impose such restrictions if it had wanted to.
There has been legislation in 1978, in 2002, in 2008, in 2011 and in 2015, where it could have done so and did not.
Secondly, nowhere in the three acts that followed the Lisbon treaty in 2008, 2011 and 2015 is there any basis for inferring a legislative restriction on the prerogative in relation to Article 50, to begin negotiation of withdrawal.
On the contrary, we say, close attention to the respective roles of Government and legislature in this context has been given by Parliament in each of these acts, and the Government's role on Article 50 has been consciously conserved.
The last of these acts is the 2015 European Union Referendum Act. That Act was passed in the clear expectation inside and outside Parliament that the final decision, made by the people in the referendum it provided for, would be implemented by the Government. At the heart of the referendum campaign between remainers and leavers was the proposition that the referendum would provide the definitive answer to the question of our future inside or outside the European Union, and the assumption that this was so was surely clear from the vigour with which the campaign was fought by both sides.
Parliament passed the 2015 Act and provided for the referendum, we say, in full knowledge that the Government had publicly and repeatedly committed to implement the outcome and fully expecting it to do so. We say, too, that because implementation of a decision by the people to leave the EU would require withdrawal from treaty obligations, Parliament expected also that this would be done in the normal way, by use of prerogative powers. We say Parliament definitively and deliberately assigned to the public vote and to prerogative action, the very question it is said it now needs to ask itself again in precisely the same terms.
Parliament passed the 2015 Act in the clear knowledge, and expectation, that the process by which the exit from the EU would take place was set out in Article 50 of the Treaty on European Union.
It knew what would happen when that process was begun, and it took no step, made no provision, imposed no constraint, to prevent the Government giving notice to do so in the usual exercise of prerogative power.
So, my Lords, the triggering of Article 50, we say, will not be an exercise of prerogative power on a whim, or out of a clear blue sky. It is the logical conclusion of a process in which Parliament has been fully and consciously involved, a process in which Parliament resolved to put a clear and decisive question about our nation's future to the British people, and in which Parliament expected the Government to act on the answer they gave.
None of this means, of course, that Parliament will not be closely involved in the process of the UK's withdrawal from the EU over the coming months and years. Through parliamentary debate and scrutiny, through the procedures set out in the Constitutional Reform and Governance Act for scrutinising the withdrawal agreement which Article 50(2) envisages, and through legislation in the form of the Great Repeal Bill to deal to the extent necessary with the domestic law consequences for former treaty-dependent rights and obligations, Parliament will continue to exercise its sovereignty as it does these things, both when it legislates and when it chooses not to, because Parliament can demonstrate its sovereignty, we say, as much when it decides not to act as when it acts. Parliament is sovereign to impose whatever legal controls it wishes on the prerogative, and it is sovereign to choose not to, or to rely on political rather than legal controls on the Government. That must be what parliamentary sovereignty means.
The position of the respondents and others in this case has always been that they have no interest in derailing Brexit but only in defending Parliament's role in the process.
But if this is all about standing up for Parliament, I say Parliament can stand up for itself. When it comes to leaving the European Union, Parliament has had full capacity and multiple opportunities to restrict the executive's ordinary ability to begin the Article 50 process and it has not chosen to do so.
However much they may wish it had, those who support parliamentary sovereignty should, we submit, respect this exercise of parliamentary sovereignty too.
So, my final submission, my Lords, is that in the context of this case, the imposition of a legislative precondition by the courts which Parliament did not choose to impose itself, cannot be supportive of parliamentary sovereignty, but must be positively inconsistent with it. In the delicate balance of our constitutional settlement, this court should, we submit, resist the invitation to make such an imposition.
My Lords, as I indicated, there are some further submissions that the appellant wishes to make. Mr Eadie and Lord Keen will make them. Unless there is anything further I can assist with on what I have said, those are the submissions I wish to make at this stage.