BREXIT: Constitutional Aspects
By Philip Goldenberg

Brexit: Parliament Should Assert its Rights
Article 50 starts by saying: "Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements."
What does this mean in the UK?
There are three views: that the prerogative power suffices; that Parliamentary consent is needed; that an Act of Parliament is needed.
The third view is overstretched or, as Robin Butler put it in another context, more weight is being put on the proposition than the law will support. It relies on the proposition that the start of a process which may lead to a change in statute law requires statute law. That is hyperbolic.
Whether the first or second proposition is right would no doubt be clear if we had a Constitution, but we don't!
So I think Parliament should assert its rights with a Motion, like the one that follows, in both Houses:
"This House
» taking note of the outcome of the advisory referendum on the United Kingdom's membership of the European Union;
» taking note that there was no clear proposition as to the United Kingdom's future relationship with the European Union;
» believes that Article 50 should not be triggered without such a proposition being approved by both Houses of Parliament; and
» accordingly calls upon Her Majesty's Government, prior to triggering Article 50, to report to both Houses with such a proposition; and
» believes that such report should include
» the views of the Scottish Government, the Welsh Executive and the Northern Island Executive; and
» formal advice from the Attorney-General as to the legal rights of those bodies in relation to the United Kingdom's future relationship with the European Union"
Additionally, I think think that the Supreme Court would run several miles from interfering with the internal workings of the UK Parliament. But it would have jurisdiction as to any conflict between the UK and Scottish Parliaments, including whether the assent of the Scottish Parliament would be required to all the legislative changes to the Scotland Act which would be needed for a withdrawal from the EU. There is something called the Sewel Convention which is relevant.