A legal challenge to the UK Government on Brexit can proceed to a full hearing in the Scottish courts, the country's most senior judge has ruled.
Lord Carloway, the Lord President, said a previous decision to dismiss the case had "erred" in ruling that there was "no real prospect of success".
He has now granted permission for the challenge - which has been brought by a cross-party group of politicians from Holyrood and the European Parliament - to proceed.
Jo Maugham QC, director of the Good Law Project and one of the petitioners, tweeted: "The Inner House of the Court of Session has given us permission."
While Lord Carloway was critical of the "rhetoric and extraneous and irrelevant material" in the petition, he stated there was a "point of substance" which should be "argued in the normal way" in court.
Labour, Scottish Green and SNP representatives united to bring forward the legal challenge, with Green MSPs Andy Wightman and Ross Greer, SNP MEP Alyn Smith and Labour MEPs David Martin and Catherine Stihler all involved, along with Mr Maugham.
The group believe the UK Parliament could unilaterally halt the Brexit process if the final deal negotiated by the Government is rejected by MPs in the House of Commons.
They claim this offers a third option, instead of Britain having to choose between a bad deal on the UK's future relationship with Europe or crashing out of the EU with no deal.
The group is ultimately seeking a definitive ruling from the European Court of Justice (CJEU) on whether the withdrawal process triggered under Article 50 of the Treaty on European Union can be revoked by the UK on its own, without first securing the consent of the other 27 EU member states.
Their legal team went to the Court of Session - Scotland's highest civil court - in Edinburgh in February to ask a judge to refer the question to the Luxembourg court.
Judge Lord Doherty originally refused to move the case on, saying the issue was "hypothetical and academic", and that he is "not satisfied the application has a real prospect of success".
However, in his opinion Lord Carloway said: "The issue of whether it is legally possible to revoke the notice of withdrawal is, as already stated, one of great importance."
He added: "On one view, authoritative guidance on whether it is legally possible to do so may have the capacity to influence Members of Parliament in deciding what steps to take in advance of, and at the time of, a debate and vote on the European Union (Withdrawal) Bill.
"After all, if Parliament is to be regarded as sovereign, the Government's position on the legality of revoking the notice may not be decisive."
Lord Carloway said that given the case related to "a matter of very great constitutional importance", the court had taken "quite some time to consider the petition" - although he said this was "an exceptional course and it is not one which a court should follow in the ordinary case".