The Supreme Court will pass its judgment on the UK Government's appeal over triggering Article 50 later on Tuesday.

Downing Street has appealed to the country's highest court to permit the Prime Minister beginning the country's legal exit from the European Union without having to first gain Parliament's approval.

The appeal process began after the High Court ruled against the UK Government in November.

Lawyers acting on behalf of Downing Street have argued triggering Article 50 falls within Theresa May's "prerogative powers" - which once belonged to the monarch.

The Scottish Government separately intervened in the case to put forward their argument the Scottish Parliament must be consulted on before the legal mechanism is triggered.

Lord advocate James Wolffe argued leaving the EU would "change the legislative competence of the Scottish Parliament".

Since the beginning of devolution, Westminster has not changed Holyrood's competence without seeking the passing of a legislative consent motion from MSPs.

Such a motion would not be a "veto" over Brexit, argued Mr Wolffe, but will decide if Holyrood gives its consent to the "effects" of leaving the EU.

First MinisterNicola Sturgeon has vowed to give MSPs a vote on triggering Article 50 "no matter what" the court rules.

The UK Government has called on the court to reject the devolved administration's attempts to secure a consent motion.

Lord Keen, the advocate general for Scotland, told the Supreme Court: "International relations, including relations with territories outside the United Kingdom, the European Union (and their institutions) and other international organisations... are reserved matters."

He argued the Scotland Act makes it "perfectly clear" the country's "relationship with the European Union" is not part of Holyrood's powers.