Nick Barber (Fellow, Trinity College Oxford), Tom Hickman (UCL and barrister at Blackstone Chambers), and Jeff King (Senior Lecturer in Law, UCL) write: In this post we argue that as a matter of domestic constitutional law, the Prime Minister is unable to issue a declaration under Article 50 of the Lisbon Treaty – triggering our withdrawal from the European Union – without having been first authorised to do so by an Act of the United Kingdom Parliament. Were he to attempt to do so before such a statute was passed, the declaration would be legally ineffective as a matter of domestic law and it would also fail to comply with the requirements of Article 50 itself.

There are a number of overlapping reasons for this. They range from the general to the specific. At the most general, our democracy is a parliamentary democracy, and it is Parliament, not the Government, that has the final say about the implications of the referendum, the timing of an Article 50 our membership of the Union, and the rights of British citizens that flow from that membership. More specifically, the terms and the object and purpose of the European Communities Act 1972 also support the correctness of the legal position set out above.

The reason why this is so important is not only because Article 50, once triggered, will inevitably fundamentally change our constitutional arrangements, but also because the timing of the issue of any Article 50 declaration has major implications for our bargaining position with other European States, as we will explain. [Continue reading…]