 I'm delighted to be joined by Professor Kenneth Armstrong, who is Professor of European Law here at the Faculty of Law at the University of Cambridge and Director for the Centre of European Legal Studies. Kenneth, you've written a paper basically analysing the Vote Leave campaign proposals. They've published a roadmap for withdrawal. As part of that proposal, they've talked about alternative methods of actually leaving. Can you tell me a little bit more about that and what your analysis of that is? Sure. In one of our other videos, we talked about what's called the Article 50 withdrawal process. This was a mechanism introduced in the Lisbon Treaty to actually allow a member state to withdraw from the European Union. It sets down certain rules and timeframes for that process. The Vote Leave campaign and their roadmap have suggested that that perhaps isn't the only mechanism for withdrawal and they've suggested two other possibilities. One is to use what is Article 48 of the Treaty, which is the normal method for revising the treaties. The other mechanism that they have talked about is to invoke general norms of international law, particularly the Vienna Convention on the Law of Treaties. If we just take those two in turn, looking at the first one, the use of Article 48, the analogy that they have drawn is with when Greenland was brought out of the European Union through a renegotiation of the treaties. There wasn't a formal withdrawal mechanism in place at the time under what is now the Lisbon Treaty. The Vote Leave campaign used that analogy to say, well, there's another mechanism for us to do, but there's two reasons why that's not going to work and one for the reason why it's not a really good idea anyway. Well, I don't think it's going to work is that Greenland was, of course, part of the territory of Denmark. It was simply renegotiating the boundaries of Denmark's membership. It wasn't the withdrawal of a complete member state from the European Union. So I don't think that analogy works anyway. But the second reason is that, of course, we now do have a specific mechanism in the treaty that is Article 50 and the European Court of Justice made it very clear that when we have a specific provision in a treaty that lays down the ground rules for an activity, then we need to use it rather than on any general legal provisions. So I don't think the Greenland analogy works. It's also perplexing that they would think about using Article 48 anyway because the voting rules are different from Article 50. That is to say every national government has a veto and potentially every national parliament has a veto in that any renegotiation of the treaties under Article 48 requires ratification in the member states. So I don't think the analogy works and I don't think it would, in fact, be more desirable to use that mechanism for the UK because of the possibilities of veto rights. The other mechanism then is the Vienna Convention of the Law of Treaties, which lays down, if you like, the general international law framework on treaties. Yes, there are provisions in the Vienna Convention that might allow for withdrawal from a treaty in a much shorter space of time, so you might think that might be desirable. But the Vienna Convention itself makes clear that its provisions only apply to international organisations to the extent that the rules of those international organisations themselves don't lay down more specific rules. And of course Article 50 is the more specific rule in the case of the European Union. So I think the arguments that suggest that the Vienna Convention can be invoked are somewhat implausible. And my experience of reading many judgments of the European Court of Justice is that it would be unlikely to support the use of a more general international law framework when there is a much more specific European law mechanism laid down in Article 50. So you said there about time, that's a very interesting point, because something else that the roadmap actually identified was a general principle of trying to get the withdrawal complete before May 2020. And how do you analyse the possibility of that? I think one of the interesting contributions that the roadmap makes is to say that following the vote on Thursday we then need to think about then what will happen both in terms of domestic law and European level over the course of the next Parliament. And the suggestion in the document is then that over the course of the next, what will be the next four years taking us up to May 2020, the withdrawal agreement would be negotiated and finalised and this would be a realistic time frame. Now the one important thing to say about that of course is that the time frame that matters is the time frame in Article 50. Article 50 itself tells us that once a member state notifies the European Council of its intention to withdraw, then the clock starts running and there is two years to negotiate the withdrawal agreement. So it's the two year time frame that is in fact more important. Now the vote leave campaigner suggesting perhaps that there is no urgency to triggering Article 50 and in fact there is no automaticity to triggering Article 50 if in fact the vote is to leave the European Union. That said the Prime Minister and indeed the Treasury have indicated that if the vote is to leave then it is likely that Article 50 will be triggered fairly quickly. So in that case it's a little unclear to me why is that the end of sort of May 2020 is the relevant deadline rather than the two years from the moment when Article 50 might be triggered. It is true to say that this two year time period can be extended. It could be extended for a further period of time but that requires the unanimous consent of every government. So while each individual member state doesn't have a veto over the deal, they do have a veto over extending the time frame. And that really changes the UK's bargaining position I think in this withdrawal agreement because if the Article 50 is triggered relatively quickly and time period starts to run then the closer we get to the end of that time period for an orderly withdrawal then the greater the pressure is on the UK to do a deal. And if what it wants is to extend the time frame it's going to require the consent of all the other member states. And it's not necessarily in their interest to offer that at a time where they fear that they have a stronger bargaining position. So I think that it is entirely plausible that a withdrawal agreement can be done in this time period but the rules of Article 50 don't necessarily work in the UK's favour in terms of bargaining power. But also in terms of the substance of the deal of what is capable of being negotiated in two years. I think everybody now accepts that Article 50 is ambivalent in that in essence there are two elements to it. One is if you like the divorce, the withdrawal in and of itself which could simply be done and dusted without too great difficulty. But the other element is of course the future relationship of a withdrawing state with the European Union and particularly if it wants to agree rules on trade and access to the single market etc etc. And so in order for all of that to be done in a two year time period using the rules of Article 50. That tends to me to suggest a relatively limited type of agreement including the divorce and including a relatively more like a Swiss style EU free trade deal. We've talked before about the kind of models that there might be out there whether it's an EEA style agreement or other types of future relationship. My reading of the Vote Leave roadmap is that it's pushing towards a very minimal Swiss style free trade agreement. Maybe with future agreements after withdrawal, negotiations using the normal EU rules on trade, on sexual issues over time. So I think the thrust of the roadmap is interesting in suggesting that perhaps that's what they have in mind, a Swiss style free trade agreement supplemented by bilateral arrangements over time. The time frame is really going to enforce on us a very lightweight agreement at this point. I think it will be to get into some of the more difficult procedural rules the more dense the agreement is including areas that are outside of what we call the exclusive competence of the European Union. Those areas which are shared powers between the EU and the member states. Then we end up with something which is called a mixed agreement because it involves not just the powers of the EU but also the powers of the member states. Article 50 tells us about the negotiation on behalf of the union therefore in terms of its powers and competencies. The more we add in elements that are also within the powers and competencies of the member states and they are relatively extensive, then the more it might be a so called mixed agreement. There is that will require unanimity and those elements will also require ratification. So in order to avoid those elements of potential veto power, whether of national governments or of national parliaments, one might understand that the vote leave campaign would push for something within the trade policy competence of the European Union, the common commercial policy that is in principle at least the exclusive competence of the European Union to allow that negotiation to go ahead and be carried out within that time period. So once we start negotiating this position within the UK, how do you see that process happening within the constitutional bodies of the UK? There are a number of unknowns about this in terms of what the negotiating teams would look like, the road map sets out the idea that there should be a cross party negotiating team, I think that's understandable. What it doesn't say anything about though is the involvement of the devolved institutions, particularly the governments or parliaments or the constituent nations of the UK. And of course that might be particularly important as we begin to see how the voting patterns shape up across the UK. But also in constitutionally it's important that in as much as any of the legislative changes that are being suggested that might happen in this next parliament might impact upon the prerogatives and powers of the Scottish parliament for example, the recent amendment to the Scotland Act 2016 makes clear that the consent of the Scottish parliament may be required for some of these changes and it may not be likely that that will be forthcoming, therefore posing a potential constitutional crisis with the devolved administrations and I think there are other risks of constitutional crisis in this road map. There is a suggestion of introducing a bill into parliament immediately to limit some of the scope of application of EU law in the UK in relation to aspects of deportation of criminals. There's something about the limitation of the application of the Charter Fundamental Rights and something a bit more ambiguous about restricting big payouts to big business. I'm not entirely sure of what that has in mind. But particularly the idea that this legislation prior to the UK's actual withdrawal from the EU would lead the UK into conflict with EU law to no longer be abiding by its EU law obligations is of course likely to then lead to litigation for the national courts and I think it would be to put our judiciary into an incredibly difficult constitutional position forced to choose between the will of the UK parliament and the UK is what it still would be continuing obligations under EU law. Now it may well be that this legislation will never get passed. It is not clear to me that there will be the necessary majority in the House of Commons for this proposed bill to ever get through and of course the House of Lords may end up blocking for some period of time that legislation. So it may well be that it may not come to pass but I think it is potentially very risky for this to be proposed in a way that would provoke a constitutional crisis which would in reality end up with our courts potentially having to challenge the sovereignty of parliament at exactly the point where the leave campaign is arguing that there will be a restoration of sovereignty to the UK parliament. So I'm not sure that it's even in the vote leave campaign's own interest to propose the bill that they've laid out in the roadmap. Thank you very much indeed. That's really extremely helpful.