The "Brexit" case was brought by four separate groups of claimants, who argued that only parliament can invoke Article 50 of the Lisbon Treaty, and that the government’s intention to trigger Article 50 under the powers of the Royal Prerogative was ultra vires. The arguments were heard by three senior judges – Thomas LJ (the Lord Chief Justice), Sales LJ and Sir Terence Etherton (the Master of the Rolls) – in the High Court in October.

In summary, the court has accepted the principal arguments of the claimants, holding that "the Government does not have the power under the Crown’s prerogative to give notice pursuant to Article 50 for the UK to withdraw from the European Union". We understand that the claimants have sought a formal declaration to this effect from the court.

The government has sought, and been granted, certification from the court to permit a “leapfrog” appeal to the Supreme Court. This is not the same as a formal application for permission to appeal, which would have to be approved by the Supreme Court itself, although if such an application is made it is unlikely to be refused. Some commentators are suggesting that any appeal to the Supreme Court may be heard as early as 7/8 December 2016.

We will continue to monitor developments.