The UK Government does not have to gain the consent of MSPs before it triggers Article 50 to leave the European Union, the Supreme Court has unanimously ruled.

The Scottish Government intervened in the case, which was an appeal by the UK Government to allow the Prime Minister to begin the leaving process without seeking MPs' prior approval.

It put forward the argument that the Scottish Parliament must be consulted on before the legal mechanism is triggered but this was rejected by the 11 justices of the Supreme Court.

The justices rejected Downing Street's appeal to bypass Parliament by eight to three, legislation will now be put forward by the UK Government to start the process.

The SNP say they will submit 50 amendments to the legislation including having to force the UK Government to win the approval of each devolved government and executive.

In their written judgment, the justices said: "The lord advocate and the counsel general for Wales were correct to acknowledge that the Scottish Parliament and the Welsh Assembly did not have a legal veto on the United Kingdom's withdrawal from the European Union.

"Nor in our view has the Northern Ireland Assembly."

They added: "In reaching this conclusion we do not underestimate the importance of constitutional conventions, some of which play a fundamental role in the operation of our constitution.

"The Sewel convention has an important role in facilitating harmonious relationships between the UK Parliament and the devolved legislatures.

"But the policing of its scope and the manner of its operation does not lie within the constitutional remit of the judiciary, which is to protect the rule of law."

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

Lord advocate James Wolffe argued leaving the EU would "change the legislative competence of the Scottish Parliament" and therefore a consent motion must be sought by Downing Street.

Such a motion would not be a "veto" over Brexit, Mr Wolffe conceded during his appearance before the court, but it would have been instead Holyrood expressing its consent to the "effects" of leaving the EU.

First Minister Nicola Sturgeon vowed to give MSPs a vote on triggering Article 50 "no matter what" the court ruled.

The UK Government 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.

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.