I want to pay tribute to Mrs Miller, because her determination in the face in particular of quite outrageous racist and sexist abuse has ensured that we have the opportunity to debate whether—and, if so, on what terms—Article 50 is invoked. The whole House should be very grateful to Mrs Miller.
The Divisional Court and the Supreme Court carried out their constitutional responsibilities by affirming the supremacy of Parliament. It is now for this House to live up to our constitutional responsibility. It is for us to scrutinise a Bill of enormous importance to the future of this country.
I think that the Bill requires amendment, in particular to ensure parliamentary sovereignty as the process of withdrawal occurs over the next two years. Noble Lords know that the Prime Minister has promised that any agreement with the European Union on the terms of our withdrawal and our future relationship with the EU will require the agreement of both Houses of Parliament. She has said that the agreements will so require before any agreement is put to the European Parliament for its consent. That promise should be written into the Bill. A political promise, made by the Prime Minister in good faith, is no substitute for a clause—an obligation—in an Act of Parliament. The reason for that is that political circumstances can change; Prime Ministers can change over the next two years. On a matter of this importance, it is vital to ensure that there is a clear and binding obligation on the Government to return to Parliament at a defined time to seek the agreement of both Houses of Parliament for the terms of any agreement. As the noble Lord, Lord Kerr, said, this Parliament must have at least the same powers that the European Parliament has to disagree with the terms of any draft agreement.
In the course of this debate—I have listened to much of it and read the rest of it—I have heard only two arguments for why this political commitment should not be included in the Bill. The first is that we should get on with it—that is, get on with notification. The answer, of course, is that to amend the Bill in this way would not affect the Prime Minister’s deadline of the end of March for notification. The only other argument that has been made by noble Lords is that we must be very careful not to weaken the negotiating power of the Government in Europe. However, the Prime Minister has already promised to seek the consent of both Houses for any agreement that the Government reach with the EU. If there is any weakening of our negotiating position then it is the result of the Prime Minister giving that commitment, not the result of writing it into the Bill. In any event, and again the noble Lord, Lord Kerr, made this point, surely it will strengthen the Government’s hand for the Prime Minister to be able to say to the Europeans that she has to get the deal through Parliament. Of course Parliament has previously imposed legally binding duties on Ministers to secure parliamentary approval before a treaty is ratified—for example, Section 20 of the Constitutional Reform and Governance Act 2010 and Section 2 of the European Union Act 2011. The question is: why not in this Bill?
I am also concerned about what happens if there is no draft agreement between the UK and the EU on the terms of our withdrawal. In my opinion, parliamentary sovereignty must also apply in those circumstances. Surely it must be for Parliament to decide whether we prefer no deal or the deal offered by the EU. It is for those reasons that I have added my name to an amendment that would require parliamentary approval for an agreement or for no agreement. The Supreme Court recognised the constitutional requirement for Parliamentary sovereignty. I hope noble Lords will do likewise.