'Difficult and delicate issues' raised by Brexit court challenge, says Lady Hale
One of the Supreme Court justices who is due to hear the Brexit appeal next month has spoken of the "difficult and delicate issues" raised by the case.
Deputy president Lady Hale is one of a panel of 11 who will decide the matter in a four-day hearing expected to start on December 5.
The Government is appealing against a High Court ruling that Theresa May must seek MPs' approval to trigger the process of taking Britain out of the European Union.
In one of the most important constitutional cases in generations, three senior judges ruled that the Prime Minister does not have power to use the royal prerogative to trigger Article 50 of the Lisbon Treaty to start the two-year process of negotiating Brexit without the authority of Parliament.
In a speech given in Malaysia on the evolving constitutional role of the UK Supreme Court, Lady Hale said: "Just before I left to come here, a unanimous divisional court held that the Secretary of State does not have power under the royal prerogative to give notice to withdraw from the European Union.
"The court held that just as making a treaty does not change the law of the land, unmaking it cannot do so, but triggering Article 50 will automatically have that effect.
"What has to be done instead is perhaps not so clear. But the case is destined for our court, so I must say no more.
"The case raises difficult and delicate issues about the constitutional relationship between government and parliament. What is meant by the exercise of the executive power of the state?
"To what extent can it be exercised in a way which may undermine the exercise of the legislative power of the state? We do not have a written constitution to tell us the answer. But I doubt whether many written constitutions would tell us the answer either."
She added: "Perhaps significantly, the Government has given up the argument that the issue is not justiciable in our courts. To that extent, at least, it is accepted that we are indeed the guardians of the constitution: if only we knew what it meant."