On 24 January 2017, the UK Supreme Court delivered its ruling in the "Brexit case", R (on the application of Miller and Dos Santos) v Secretary of State for Exiting the European Union. As had been anticipated by many commentators, the Justices decided, by a majority of eight to three, that the UK Government cannot trigger the Article 50 process to withdraw from the EU without an Act of the UK Parliament.

The key legal issue in the case was whether the UK Government could rely on the Royal Prerogative to commence the withdrawal process under Article 50 of the Treaty on European Union, on the basis that making treaties was within the inherent sovereign power of the UK Government. The majority of the Justices decided that the European Communities Act 1972 created EU law as a source of UK law, which therefore could only be changed by a new Act of the UK Parliament.

The UK Government has stated that, despite this set-back, it remains on track to trigger Article 50 by 31 March 2017. The Secretary of State for Exiting the EU has told the UK Parliament he is planning to publish a Bill shortly and has warned both Houses of the UK Parliament against trying to "thwart" or "delay" Brexit. Whilst the UK Government has a majority in the UK House of Commons, it does not in the UK House of Lords; it is expected that opposition parties will try to force a number of amendments to the European Union Withdrawal Bill and the nine Liberal Democrat MPs have been instructed to oppose the Bill.

The UK Supreme Court Justices also ruled unanimously that the UK Government does not need the consent of the Scottish Government, or of other devolved administrations, before it triggers the Article 50 process. This has angered Scotland's ruling party, the Scottish Nationalist Party, with Scotland's First Minister, Nicola Sturgeon, commenting that the need for a new referendum on Scottish independence was "ever clearer".

The lawyers and judges have, for the time being at least, done their bit; it is now over to the politicians again…