But first things first. The case was brought earlier this year after Nicola Sturgeon presented a draft bill for a referendum to be held on October 19, 2023. To clarify whether the Scottish Parliament had the authority to legislate in this matter without the agreement from Westminster, she invited the Scottish Lord Advocate, Dorothy Bain, KC, to refer the issue to the Supreme Court.
This approach was justified by Nicola Sturgeon with reference to her desire to follow the path of the law. Any other way, she claimed, would taint the legitimacy of Scotland’s independence in the end, jeopardising support and recognition from abroad, including from within the EU.
This tactic was surprising. One might have expected Scotland to adopt the referendum bill, then challenge the Westminster government to bring an action in the courts to overrule it. Vetoing the will of the democratically elected representatives of Scotland would have increased the sense of disenfranchisement and added impetus to the campaign of independence. Bringing the action first has rather reduced the matter to a technical legal battle about dry questions of legislative competences in which few are invested at this early stage.
In order to persuade the court that it should take the case, Scotland had to cast doubt on its authority to legislate on the referendum. Rather than confidently claiming that Holyrood obviously had the authority to legislate, the Scottish Lord Advocate instead asserted that her case in favour of the bill was finely balanced. After all, the Supreme Court would only hear the case if there were doubtful or contested issues before the Lord Advocate that need clarification through its judgement.
By bringing the case, Nicola Sturgeon moved her campaign for a referendum away from broader questions of legitimacy and democratic principle that seem to favour Scotland onto territory controlled by the authorities in London. The legal framework which determines whether or not Scotland can hold an official referendum is set out by Westminster, in the form of the Scotland Act 1998. The Act reserves issues relating to the United Kingdoms of Scotland and England, and to the Westminster Parliament, denying competence on these matters to the Scottish Parliament.
This put the SNP government in a difficult spot. To its own constituency, it had to argue that the proposed referendum was a major step towards implementing its manifesto pledge of moving decisively towards independence. However, when facing the court, the Scottish authorities had to claim the opposite. In order to establish that the proposed referendum would not affect the future of the Union, or the sovereignty of the Westminster Parliament, the Lord Advocate had to emphasise its merely indicative nature – a public consultation exercise, no more.
The Supreme Court gave short shrift to this somewhat two-faced argument, noting that the SNP and the Scottish Government were campaigning so hard for the referendum, precisely because it would have a strong, if not decisive, effect on the debate about possible independence. Evidently, this would produce “important political consequences relating the Union and United Kingdom Parliament”, as the court put it.
This short and sharp defeat should have been the end of it. However, the SNP intervened in the case, offering its own, additional submissions, which the court answered briefly and with potentially disastrous results for the independence campaigners.
The SNP introduced the argument that the people of Scotland are entitled to self-determination as a matter of international law. In truth, this should have been Scotland’s main angle of attack, but at a later stage. That argument would hold that Scotland is an entity entitled to self-determination. If so, then it would be manifestly unlawful for the Westminster government to withhold the only means to actualise that right, a referendum, arbitrarily.
The SNP, however, raised the principle of self-determination in an incidental way, and in this early, initial phase, merely as a tool for interpreting the provisions in the Scotland Act on reserved matters. The SNP expected the Supreme Court to confirm that Scotland obviously enjoys the right to self-determination. Accordingly, the court should interpret the reserved powers in the Scotland Act restrictively, to give effect to that principle.
The court confirmed that it will generally try to interpret UK legislation in harmony with international law, but that this would not overrule UK statues where the law was clear.
Worse for Scotland, the court addressed whether self-determination applies in this instance at all. Basing itself on a ruling of the Canadian Supreme Court relating to Quebec a quarter of a century ago, the court appears to have denied a right at international law for Scotland to effect secession from the UK. Self-determination in the sense of secession only applies to classical, overseas colonies, it seems to assert.
This finding is, of course, not consistent with the UK’s own position in this case and with developments in contemporary international law. Had the referendum of 2014 resulted in a clear vote for Scottish independence, Westminster would have felt bound to negotiate secession under the doctrine of constitutional self-determination, which applies outside of the colonial context.
This question was not fully argued before the court and its findings need to be explored further. But at first sight, the misguided intervention by the SNP in the case has resulted in a somewhat cryptically short and possibly slightly confused dictum that is potentially calamitous for Scotland’s case. After all, the key question is whether the central government is entitled to withhold its agreement to a referendum. This depends on the question of whether or not Scotland is a self-determination entity, albeit outside of the colonial context, which should not really be subject to doubt.
Marc Weller is professor of international law and international constitutional studies at the University of Cambridge