Today the High Court handed down its judgment in the highly publicised judicial review proceedings concerning the constitutional requirements for the UK's withdrawal from the European Union (EU) and approach to invocation of the notification procedure under Article 50 of the Treaty on European Union. The Court has ruled that, according to fundamental principles of constitutional law, the Government does not have the power to trigger Article 50 without reference to Parliament.

The specific question for the court to determine was whether, as a matter of constitutional law, the Government is entitled to use prerogative powers to trigger Article 50. Prerogative powers are a body of discretionary powers held by the Crown and exercised by Government in carrying out executive functions. The exercise of prerogative power does not require prior parliamentary approval. The Government argued that the Article 50 process for withdrawal from the treaties effecting membership of the EU could be triggered by prerogative power and without further reference to Parliament as would be the case in other matters affecting international relations. It suggested that Parliament must have intended that the prerogative to withdraw would remain with the Government when the European Communities Act 1972 was enacted. However, the Court agreed with the Claimants that the proposed actions would affect not only international relations but also domestic law and the rights of individuals acquired under EU law, such as free movement between Member States. The Court's view was that Parliament cannot have intended that the "profound effects" of the European Communities Act 1972, which introduced EU law into domestic law with all the rights that this entailed, could be abrogated by the unilateral exercise of prerogative power by the Government.

The Government has already announced it will appeal the judgment. Given the constitutional importance of this case and the Prime Minister's announcement that Article 50 will be triggered by the end of March 2017, the appeal will be heard on 7/8 December by the UK Supreme Court - so leapfrogging the Court of Appeal, which is the usual venue for High Court appeals.

The Court stressed that its judgment addressed a pure question of law, as to the process for exercise of Article 50, rather than any political issue on the merits of leaving the EU. However, the judgment likely will fuel the debate about Brexit and the result of the referendum on 23 June 2016 yet further.

The full judgment is available here.