What is the supreme court ruling on? At 9.45am on Wednesday, supreme court judges led by Lord Reed will deliver their decision on the question that has vexed both sides of the constitutional debate since the yes side lost the last independence referendum in 2014: can the Scottish parliament legally hold another referendum without Westminster’s approval? This comes after Scotland’s chief law officer, the lord advocate, Dorothy Bain, referred this question to the court at the request of Scotland’s first minister, Nicola Sturgeon. Bain explained to the court that she would not be able to clear the referendum bill because she did not have “the necessary degree of confidence” that it would be within the competence of the Scottish parliament. Devolved parliaments cannot legislate on reserved matters, and the union of Scotland and England is reserved to Westminster. Will this settle the question once and for all? The Scottish and UK governments have been in deadlock over the granting of an order under section 30 – the section of the Scotland Act that allows Holyrood to pass laws in areas that are normally reserved, with the past four Conservative prime ministers refusing to do so. While both sides would welcome some long-awaited clarity, the judges don’t have to pick a side and may reject the reference as premature because the referendum bill has yet to pass through the Holyrood parliament. What arguments were put at the hearing? The Scottish government argued that such a bill – and the referendum it would sanction – was within Holyrood’s powers because the vote would merely be consultative, and not have any immediate consequences. Independence would be achieved through lengthy negotiations, as happened with Brexit. The UK government argues the polar opposite – that all constitutional law-making is reserved to Westminster – and also suggested that the application should be rejected because it is a draft bill with no legal standing. What if the court says yes? The majority of constitutional experts believe this to be the least likely outcome, but if so Sturgeon has already named the date for a second vote as 19 October 2023. SNP ministers would be expected to rush a referendum bill through Holyrood, with the support of their government partners, the Scottish Greens. What if the court says no, or not now? Sturgeon has long argued that this is about respecting Scottish democracy – the SNP won the 2021 Holyrood election on a manifesto pledging another referendum. She told her party conference in October that if this were the outcome “we will respect that judgment” but that it would leave her with no choice but to “put our case for independence to the people in an election”. There remain many unknowns around how this “de facto referendum”, as she coined it, would operate in practice, whether success would be measured as more than 50% of the vote for the SNP, or for all independence-supporting parties. If the referendum is rejected, the bill could still be taken through Holyrood by an SNP backbencher, but this is likely to result in further legal challenge from the UK government. Can we anticipate the result? No, but we do know that a conclusion has been reached in a much more timely fashion than expected. In his opening remarks, the supreme court president, Reed, explained that the five judges had 8,000 pages of written submissions to assess, and warned it was “likely to be some months before we give our judgment”; Sturgeon herself has said she expected the decision could come in the new year. Instead, the ruling comes a mere six weeks after October’s two-day hearing.