The UK Supreme Court has confirmed that the UK Government cannot trigger the formal process of leaving the European Union without an Act of Parliament.
The arguments before the Supreme Court turned on the correct application of fundamental constitutional principles relating to the scope and nature of prerogative power exercisable by the UK Government and the role of the UK's devolved legislatures in the decision to serve an Article 50 notice.
The case was heard by all 11 members of the Supreme Court (a constitutional first, at least in modern times) over four days in December 2016. The Supreme Court dismissed the Government's appeal and upheld the decision of the English High Court (the Divisional Court) on the role of Parliament in the process by an eight to three majority. The Court also determined that the devolved legislatures have no legal veto over any decision to give notice.
Immediately after the judgment was handed down, the Government confirmed that it will comply with the decision of the Court. David Davis MP, the Secretary of State for Exiting the EU, confirmed in the House of Commons at lunchtime that in the next few days the Government would propose the "most straightforward Bill possible" to allow the triggering of Article 50.
The Supreme Court's judgment was widely anticipated and provides helpful clarity on the constitutional requirements for the UK to begin the process of leaving the EU, although some important questions remain unanswered. In this article, we summarise the decision and the reaction to it so far and consider the effect it may have on commercial parties as they begin to refine and implement their Brexit contingency plans.
You can read our analysis of the judgment and its implications for commercial parties as they refine and begin to implement their Brexit contingency plans here.
For further detail on the hearing and the background to it, you may also wish to read:
Our analysis of the Divisional Court's judgment, available here
Our preview of the Supreme Court hearing, available here
and our summaries of the oral arguments put forward by parties and the interveners, available here;
The press release and full transcript of the Supreme Court's judgment, available on the Supreme Court's website, here