President of the court, Lord Reed, with whom Lord Lloyd-Jones, Lord Sales, Lord Stephens and Lady Rose agreed, said that Holyrood does not have the power to legislate for a referendum on Scottish independence.

The provision in the proposed bill on a referendum on the question “Should Scotland be an independent country?” relates to matters which have been reserved to the UK Parliament under the Scotland Act 1998, the court ruled.

In particular, it relates to the reserved matters of the Union of the Kingdoms of Scotland and England and the Parliament of the United Kingdom.

As such, in the absence of any modification of the definition of reserved matters – by an Order in Council or otherwise – the Scottish Parliament has no power to legislate for a referendum on Scottish independence.

On the question of whether the bill relates to the union, Lord Reed said that “we are in no doubt as to the answer”. 

He added: “It is plain that a bill which makes provision for a referendum on independence – on ending the Union – has more than a loose or consequential connection with the Union of Scotland and England.”

In court this morning, Lord Reed said the justices did not accept the argument of the SNP, which had intervened in the case, that Scotland should be allowed to hold another independence referendum on the basis of a right to self-determination under international law.

He said: “The Scottish National Party, which the court permitted to intervene in the proceedings, made further submissions based primarily on the right to self-determination in international law. They argue, in summary, that the limitations upon the powers of the Scottish Parliament as laid down in the Scotland Act should be restrictively interpreted in a way which is compatible with that right under international law.

“The court is unable to accept that argument. The SNP rely on the judgment of the Canadian Supreme Court in a case concerned with Quebec, but in that case the court held that the right to self-determination under international law only exists in situations of former colonies, or where a people is oppressed, as for example under foreign military occupation, or where a definable group is denied meaningful access to government to pursue their political, economic, cultural and social development. The court found that Quebec did not meet the threshold of a colonial people or an oppressed people, nor could it be suggested that Quebecers were denied meaningful access to government to pursue their political, economic, cultural and social development. The same is true of Scotland and the people of Scotland.”

First Minister Nicola Sturgeon said at a press conference in Edinburgh after the ruling that the SNP will use the next general election as a “de facto referendum” on Scottish independence.

She added: “We must and we will find another democratic, lawful and constitutional means by which the Scottish people can express their will.

“In my view that can only be an election. The next national election scheduled for Scotland is of course the UK general election, making that both the first and the most obvious opportunity to seek what I described back in June as a de facto referendum.”

Ms Sturgeon said it is now “necessary to agree the precise detail of the proposition we intend to put before the country” and that the SNP will hold a conference in the new year to “discuss and agree the detail of a proposed de facto referendum”.

Prime Minister Rishi Sunak welcomed the “clear and definitive ruling” of the court. Challenged at PMQs today by SNP Westminster leader Ian Blackford, who told Mr Sunak that “democracy will not be denied”, the prime minister responded: “Now is the time for politicians to work together.”

Dr Tarik Olcay, an expert in constitutional law at the University of Dundee, commented: “Other than the substantive judgment, it is worth noting that the Supreme Court judges listened to the intervention of the SNP in addition to the lord advocate. Those papers from the SNP made a case for the power to hold a referendum on the basis of a right to self-determination under international law.

“While this is something of a subjective concept in the population at large, it is more clearly defined in legal terms in relation to post-colonialism and military occupation. While some Scots may believe they are colonised or oppressed by the UK, the Supreme Court has were clearly ruled that Scotland is neither a colony or an occupied country and therefore not subject to the international law governing the right to self-determination.”

Murray Etherington, president of the Law Society of Scotland, said: “Today’s judgment provides definitive clarification on the law. Any referendum on Scottish independence must be lawful to ensure the outcome is clear and unambiguous.”