The Guardian view on Scottish nationalism: a warning from Catalonia

Nicola Sturgeon will put independence front and centre in her leader’s speech to the SNP conference in Aberdeen on Tuesday. That’s no surprise. Independence is what the SNP is in business for. What is more, after 12 years of SNP rule and five years on from the 2014 referendum, Scots voters show little sign of tiring of the party. Conservative advances have ebbed since Ruth Davidson quit and Boris Johnson became prime minister. Scottish Labour remains in historic eclipse. The SNP is on course to recapture Westminster seats from both parties, while a weekend poll put support for independence at 50%, the highest figure in recent times.

An imminent prospect of Brexit means a second independence referendum is once again a wholly live issue. Ms Sturgeon is expected to make a formal request for a new vote to the UK government in the coming weeks. If there is an early general election, the indyref2 demand will be a central part of the campaign, with rival parties under pressure to define their positions. Labour, in particular, will be in the SNP’s sights. Ms Sturgeon has said that, if there is another hung Westminster parliament, Jeremy Corbyn should not pick up the phone to propose a parliamentary deal unless he is willing to agree to a second vote. If the SNP gets the support that the polls currently suggest, her mandate to make that demand will be incontrovertible.

That, though, is the relatively easy bit. Translating such a mandate into a successful independence campaign will be harder. If the UK leaves the European Union, Scotland’s majority remain vote in 2016 will be viewed with deep sympathy in Brussels. But that does not mean that an independent Scotland could re-enter the EU on the same terms as the by then-departed UK. EU terms for entry could pose big questions about Scotland’s currency, tax policies and membership of the UK single market, and raise the issue of a hard border with the remaining UK.

Then there is the question of tactics. Some nationalists fear that playing things by the book by requesting a referendum from an uncooperative UK government could be a doomed strategy. They are impatient to force the pace. In Aberdeen on Sunday, the SNP hierarchy defeated attempts to debate a so-called “Plan B” – in effect a move to begin independence negotiations without waiting for London to grant a second referendum. The leadership is right to steer clear of such constitutional brinkmanship. Inevitably, Scottish eyes will have turned south on Monday. Spain’s jailing of Catalan nationalist leaders, for such long terms, has shocked Europe. Catalonia and Scotland are home to Europe’s two most developed independence movements, but they have taken, up to now, very different separatist strategies.

Ms Sturgeon has been scrupulous and right to spurn the illegal referendum route embraced by frustrated Catalan nationalists. That unilateralism has now led the Spanish courts to take the shocking course of making political prisoners of nationalist leaders. The draconian jailings shame Spain. Both Madrid and Brussels, which has refused to intervene, should do everything to resolve the situation as soon as possible. And both Scotland and Britain must commit themselves not to go down a similar route, however strong the temptations may seem.