The foundations of Scotland's devolution settlement are "being shown to be worthless", Holyrood's Brexit Minister Michael Russell has told MSPs.

He said a court ruling on the triggering of the process for leaving the European Union had also exposed statements that the UK Government and Scotland are equal partners as "empty, diversionary rhetoric".

The Supreme Court decided that while Theresa May must give MPs a vote before triggering Article 50, the UK Government is "not legally compelled" to consult the three devolved administrations.

The Scotland Act of 2016, introduced after voters opted to stay in the UK in 2014, enshrined in legislation the Sewel Convention - which states Westminster will normally only legislate on devolved matters with the express agreement of MSPs.

Read more: Holyrood Brexit minister Mike Russell accuses UK Government of 'lying' as calls for second independence referendum mount

In the ruling, Supreme Court President Lord Neuberger said "relations with the EU are a matter for the UK Government".

During a statement at Holyrood, Mr Russell said: "We're obviously disappointed with the Supreme Court's ruling about the legal enforceability of the Sewel Convention."

He said the court had ruled operation of the convention was a political rather than a legal matter, adding it was "obvious that the Sewel Convention is triggered by a UK Bill authorising Article 50 notice".

Mr Russell also argued that the ruling had been a defeat for those who believed enshrining the convention into law would represent a new status for Holyrood.

"Last year the Scottish Secretary (David Mundell) boasted in a speech about what he called 'the new realities' that the Sewel Convention was now written in law, but in its submission the UK Government left that position far behind," Mr Russell said.

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Referring to Mr Mundell and Adam Tomkins, a Tory representative on the Smith Commission which drew up the new devolution settlement, he added: "It (the UK Government) made it clear that its law - Mundell's law, Tomkins's law - was not worth the paper it was written on."

The UK Government has always accepted that a change in devolved competence requires the consent of MSPs, Mr Russell continued.

He added that now it is "in danger of overturning nearly 20 years of accepted practice under different political administrations both north and south of the border".

He told the chamber the Scottish Government will publish a memorandum setting out the implications for devolved matters, and the powers of the Parliament and Scottish ministers, after the UK Government publishes its Bill to trigger Article 50.

"And as things stand, in that memorandum, we will be unable to recommend that the Parliament gives its consent to a Bill giving the UK Government the power to trigger Article 50," he said.

He said the Scottish Government, which has set out its own alternative options on European single market membership, will use next week's Joint Minister Committee on EU negotiations to press for "sensible, compromise outcomes".

He added: "However it is becoming clearer by the day that Scotland's voice is simply not being heard or listened to within the UK.

"The claims about Scotland being an equal partner are being exposed as empty, diversionary rhetoric by the actual facts.

"Now the very foundations of the devolution settlement that are supposed to protect our interests, such as the statutory embedding of the Sewel Convention, are being shown to be worthless."

Responding to the minister, Mr Tomkins said: "When they play the man and not the ball it's always a sure sign that they know they've lost the argument."

He added: "It is the United Kingdom, not Scotland, that is the member state of the European Union and it is the United Kingdom as a whole, not its nations separately, that has taken the decision by referendum to withdraw from the European Union.

"These matters are not devolved and nothing in 'the vow' or in the Smith Commission or in the Scotland Act - any of them - has ever suggested that they should be."

Read more: Holyrood Brexit minister Mike Russell accuses UK Government of 'lying' as calls for second independence referendum mount

Mr Tomkins continued: "The SNP have spent the last seven months trying and failing to stoke grievance about Brexit. Now it seems their ambition is reduced to stoking new grievance about the Sewel Convention.

"Instead of complaining about a court judgment that's gone against them, when will the Scottish Government get on board and help make Brexit a success for all of us?"

Mr Russell responded that Tory MSPs are "letting down their constituents with every shout that they give in this chamber", and said the judgment confirmed the legislative competence of the Parliament would be altered.

Labour's Lewis Macdonald said: "He (Mr Russell) will know that the people of Scotland have voted against abandoning our neighbours precisely because we understand the threats that come from isolationism and from turning our backs on our closest friends and trading partners.

"The Scottish people do not want to turn our backs on Europe and we do not want to turn our backs on the rest of the UK. So when Mr Russell talks of closing down options, is he abandoning his Government's commitment to working together across parties and across the UK in spite of the recklessness of the Tory party?"

Mr Macdonald called on the Brexit Minister to "reject isolationism in all its forms" and back Labour's call for a UK-wide constitutional convention.

Read more: Battle lines drawn over Brexit as Nicola Sturgeon says Scotland ignored

Mr Russell said he rejects isolationism "in its entirety", adding "I do not wish to see any barriers in trade within these islands".

Green MSP Ross Greer said: "The minister has pointed out that options are fast closing for Scotland so could he confirm the timetable on which an independence referendum Bill will be introduced, as it's becoming increasingly clear that we must put Scotland's future in Scotland's hands."

Mr Russell said he could not give a timetable, adding: "The options we have placed on the table are being closed down not because of any actions by the Scottish Government, they are being closed down by the Westminster Government, so in a sense the timetable of what goes ahead now lies with the Westminster Government."

Herald View: Westminster wins from Supreme Court judgement

Liberal Democrat leader Willie Rennie urged Mr Russell to back his party's bid for a further referendum on the Brexit deal.

Mr Russell said that proposal is "not likely to win any support apart from the Liberal Democrats".