What is the Supreme Court case about?
The UK Government is challenging the Continuity Bill passed by Holyrood in March, arguing that it goes beyond the competences of the Scottish Parliament and is unconstitutional.
In the early stages of the UK Government’s oral argument by the Advocate General for Scotland, Lord Keen said the Continuity Bill “impermissibly alters” UK legislation on Brexit.
Why has the row reached the Supreme Court?
To make sure that UK law continues to function on Brexit day after 44 years of being intertwined with EU law, the UK Government put forward the EU Withdrawal Bill to copy Brussels regulations into British statute, to be kept, changed or discarded later.
However, that includes regulations in areas like agriculture, fisheries and the environment, where regulations set in Brussels were administered by devolved governments in the UK.
In order to prevent different regulatory regimes emerging after Brexit, creating trade barriers within the UK, the government in London proposed to keep hold of a number of those powers - eventually whittled down to two dozen.
Yet despite months of negotiation, the two sides could not reach a compromise on the principles of where those powers should lie, even if though they did agree that there should be some form of joint control.
The Scottish Government put forward its Continuity Bill at Holyrood, saying it needed to protect the devolution settlement by asserting its authority over the disputed powers.
What will the Supreme Court decide?
Seven judges - Lady Hale, Lord Kerr, Lord Sumption, Lord Reed, Lord Carnwarth, Lord Hodge and Lord Lloyd-Jones - will either rule that the Continuity Bill is within the competence of the Scottish Parliament; rule that it goes beyond the competence of the Scottish Parliament; or ask Holyrood to change specific portion of the bill. A ruling is not expected until October at the earliest.