The Scottish Government's top lawyer will put forward the case for Holyrood to have a veto over triggering Brexit later on Wednesday at the Supreme Court.

Lord advocate James Wolffe is tasked with convincing the court the UK Government must seek a successful legislative consent motion at Holyrood before triggering Brexit.

Under the Sewel convention, Mr Wolffe will argue, Westminster seeks the approval of MSPs before changing the legislative competence of the Scottish Parliament.

In his written submission to the 11 Supreme Court justices, the lord advocate argues "withdrawal from the EU" will "change the legislative competence of the Scottish Parliament" and "disapply or disable laws" which currently apply in Scotland.

Mr Wolffe also points out in his submission that EU funding mechanisms surrounding agriculture and fishing are administered by Holyrood as it falls within the devolved settlement.

When announcing the lord advocate's involvement in the case, First Minister Nicola Sturgeon said: "The Scottish Government is clear that triggering Article 50 will directly affect devolved interests and rights in Scotland.

"So legislation should be required at Westminster and the consent of the Scottish Parliament should be sought before Article 50 is triggered.

"Let me be clear - I recognise and respect the right of England and Wales to leave the European Union. This is not an attempt to veto that process.

"But the democratic wishes of the people of Scotland and the national Parliament of Scotland cannot be brushed aside as if they do not matter."

Mr Wolffe's appearance before the court follows his counterpart in the UK Government, Lord Keen, the advocate general.

Lord Keen rubbished Mr Wolffe's written submission describing it as without "substance".

The advocate general told the court the Scotland Act 1998, which created the Scottish Parliament, explicitly stated the country's "relationship with the European Union" does not fall within Holyrood's remit.

Lord Keen also argued the Sewel convention was political in nature and not on the statute book.

Judge Lord Sumpton questioned the advocate general's summation of the convention as it appears in the Scotland Act as amended earlier this year.

"It cannot be described as a purely political force once it is enacted in a statute," the judge argued.

In his closing remarks to the court, Wolffe said: "The conclusion of the Article 50 case advanced by the lord advocate is that there is by virtue of the Sewel convention a constitutional requirement using the terms of Article 50 that must apply before the United Kingdom and takes steps in terms of Article 50 to leave the EU.

"However, the lord advocate makes no effort in his case to explain how a convention which provides in terms that it does not apply as a rule in all circumstances, could even be a requirement, let alone a constitutional requirement and therefore there is doubt as to where that case actually goes.

"In my respectful submission, there is no substance in the case that is being advanced there by the lord advocate."

The Supreme Court hearing will end on Friday with judges not expected to pass a verdict until January.