About a week before the referendum I met with a few friends and discussed the possibility that the UK would actually vote to leave the EU and I posted the outcome of that discussion - UK and the EU (11) - The event horizon approaches - What if it is Brexit. We tried to envisage how things might go after such a referendum result and sought to identify some of the legal questions that would arise.
Now that the decision of the referendum is to leave, many of those questions are receiving some serious attention including the all-important notification (under TEU Art 50) of a "decision in accordance with constitutional requirements" to withdraw from the EU.
A key question is what amounts to such a "decision" because without such a decision there is nothing to notify.
We begin with the fact that, under the UK constitution, Parliament is sovereign. Legal opinion seems clear that the Referendum Act 2015 contained nothing to place either the government or Parliament under any legal obligation to do anything. The 2015 Act stands in contrast to the Alternative Vote referendum where the legislation placed a legal duty on the Secretary of State to implement the outcome - see Parliamentary Voting System and Constituencies Act 2011 section 8.
In March 2010, the House of Lords Constitution Committee published a report on Referendums in the UK. The government response to the report was issued in October 2010. The government agreed with the report that Parliament had to be responsible for deciding whether or not to take action in response to a referendum result.
It therefore appears that the EU referendum alone cannot amount to a "decision" to leave the EU unless it can somehow be argued that Parliament either gave its right to decide entirely to the electorate when it offered the people a vote on the question. As a question of law, it does not appear to me that Parliament did this though it cannot be denied that the referendum result places considerable political pressure on the government to act. The "consultative" nature of this referendum was made clear to Parliament in the Briefing on the Referendum Bill- at page 25 and it was mentioned during debate in response to an amendment put forward by Mr Alex Salmond that would have required a majority in each of England, Wales, Scotland and Northern Ireland. The amendment was rejected.
Whether a Bill would get through Parliament is a political question. Most Members of Parliament appear to be in favour of remaining in the EU though it does not necessarily follow that they would choose to vote against the clear outcome of the referendum given its undoubted political force. Similarly, in the House of Lords, peers may not be personally in favour of leaving the EU but they would be unlikely to seek to prevent Brexit given that there was a manifesto commitment by the elected government to hold the referendum.
Notice under Article 50 starts the 2 year clock running. There is a view that when the exit process is triggered it is not possible for the UK to unilaterally stop the clock or withdraw its notice. Unless the point was to be successfully challenged in the Court of Justice of the EU, it may be safer to assume that this view is correct. Perhaps the government will seek clarity about this and, in any event, it would seem sensible to establish what the rules are before entering into any negotiations. Time will tell.
If Parliament stated in legislation (or otherwise) that a "decision" to leave the EU has been made then Parliament could leave the giving of notice to Ministers. Alternatively, the legislation could control the process - for example, by specifying that the giving of the notice required debate and approval by each House before it was communicated to the EU.
Some notable writers have argued that an Act of Parliament is not necessary to authorise Ministers to give the Art 50 notice since Ministers may lawfully act using "Royal Prerogative" powers relating to foreign affairs and treaties. Such arguments should address the questions of whether the UK has made a legally binding decision, how such a decision was actually made and whether the Royal Prerogative powers in relation to treaties are wide enough to permit Ministers to give the required notice.
The government has the right to make and unmake treaties. That takes place on the international level and it will create effects that bind the UK in International Law. What prerogative powers may not be used to do is to alter domestic law. That is the sphere of Parliament. The Bill of Rights 1689 states that laws may not be dispensed with or suspended without the consent of Parliament. The UK operates a dualist approach to treaties. A key issue then will be whether the giving of notice under Article 50 will change domestic law given that the notice leads inexorably to the UK leaving the EU. The practical impact of this is that those rights operating within the UK by virtue of the European Communities Act 1972 would be lost.
Various arguments have been presented in articles and on blogs as the links below indicate. I expect that if the matter gets to the courts the case will be finely balanced and could go either way. We shall see!
On 14th July, a discussion took place at University College London during which there was examination of the question of whether an Act was required to authorise Ministers to trigger Art 50. The discussion may be viewed here.