My Lords, first, I thank all the contributors to this debate. It is right that we have taken the time to discuss it at length, because this amendment has potentially serious implications for delivering a successful Brexit. Of course, I understand why this amendment might look notionally appealing, at least—it triggers a greater role for Parliament should any of the deadlines set by the amendment pass without their terms being met—but let me be very clear; this is not an innocuous, measured amendment. It contains a number of constitutional, practical, legal and political difficulties, all of which we should seek to avoid if we are to leave the EU with the best deal possible, which is what the Government want to achieve. Indeed, this amendment would create a profound constitutional shift in terms of which branch of the state holds the prerogative to act in the international sphere, a point so well made by my noble friends Lord Lamont and Lord Howard and by the noble Lord, Lord Howarth, from the Labour Benches.
I do not suppose that those who are proposing this amendment are making this suggestion lightly, but I cannot support such a move, as I do not believe that it is in the best interests of the country to redefine the nature of our democracy in this way. It is a well-established feature of our constitution that the Executive represent the country in international diplomacy, and this constitutional arrangement exists for very good practical reasons. In any negotiation, there are judgments to be made as to what can reasonably be achieved. Those judgments can be made only by those engaged on the detail. It would be impossible for negotiators to demonstrate the flexibility necessary for an effective negotiation if they are stripped of their authority to make decisions. That will do nothing but guarantee a bad deal for the UK, which is something I hope we all wish to avoid. If the UK is to be a trusted and effective negotiator, with the EU or anybody else, the Executive branch must be competent to negotiate, just as they are competent to act on their own judgment in other areas of international relations. I speak in strong terms, because I want to demonstrate the seriousness with which the Government take this amendment, its implications and the precedent it will set.
The drafting of the amendment itself is of further concern. It states that a draft of the withdrawal agreement must be approved by the Commons before it can be concluded, but it is not clear what “conclude” means in this context. This may seem a lesser point but noble Lords will understand that we need legal certainty to ensure that the vote occurs at the right time in relation to the process of withdrawing from the EU. We would not want to end up in a perverse situation in which a vote must be offered while negotiations are ongoing, for instance. The vote must happen once the final text has been agreed. Until that point, there would be nothing for Parliament to vote upon, given that ultimately, of course, nothing is agreed until everything is agreed.