by Daniel Cetrà

It is tempting to think of Catalonia and Scotland as being in similar position.

Both have pro-independence governments, which enjoy parliamentary majorities owing to the support of smaller secessionist parties.

Around 45 per cent of Catalans and Scots support independence. And both nations see demands to hold independence referendums – in Catalonia they have been running strong since 2012 and there is wide support (80 per cent) for a referendum, assuming the Spanish government agrees to it.

Despite these similarities, the differences are key. Scots voted in an independence referendum supported by the British Government, while Catalans may vote in a referendum opposed by Madrid.

The position of the Spanish Government and most Spanish parties has always been that such a referendum is unconstitutional. The strategy of the Spanish Government has consisted of resorting to challenges via the Constitutional Court.

After several requests to hold a negotiated referendum, six consecutive years of mass, pro-independence demonstrations on Catalonia’s national day, most recently this weekend, the Catalan government has decided to organise an independence referendum unilaterally.

The Catalan government has already also a symbolic vote on independence in 2014, and a subsequent election which returned a pro-independence majority.

The new referendum has been called for October 1, amidst deep political tension between governments and, within Catalonia, between pro-independence and unionist parties.

The referendum law has already been suspended by the Constitutional Court, and Spain’s attorney general has ordered security forces to prevent any preparations for the vote. All members of the Catalan Government have been accused of perverting the course of justice, disobedience and misuse of public funds. However, the Catalan government has announced that it will go ahead and that the vote will be binding.

The situation reflects a debate between legal and democratic legitimacy. In contrast with British unionism, the appeal to unionism in Spain has become a predominantly legal argument rather than an appeal to the economic and social benefits of the status quo.

There are also competing visions of sovereignty and nationhood. The view of a single Spanish sovereignty enshrined in the constitution is supported by all unionist parties except Podemos, the alternative left group.

Supporters of the referendum contend that Catalans are a political community entitled to self-determination and that this right should prevail over narrow interpretations of the Spanish constitution.

Amidst increasing political tension, both the outcome and consequences of the referendum are uncertain. Two key issues will be turnout and the Spanish Government’s response. Perhaps paradoxically, independence supporters need unionists to get out and vote and take part in the debate.

A turnout of 50 per cent or higher would be a success for the Catalan Government, giving the referendum legitimacy and putting the Spanish Government in a difficult position. A turnout similar to the 2014 symbolic vote (36 per cent ) would be a defeat for the Catalan Government, probably putting an end to the independence project for some time.

In terms of results, and again paradoxically for the independence movement, a narrow Yes victory would be preferable to a large victory. It would make the vote more legitimate as it would better reflect actual public opinion. The most recent poll suggests that 41 per cent of Catalans supports independence while 49 per cent oppose it.

The Spanish Government’s goal is to prevent the referendum – and, if that is not possible or convenient, to encourage as low a turnout as possible. Spanish Prime Minister Mariano Rajoy has two main options.

The first, which seems more likely at the moment, is to seek to prevent the vote using ordinary methods. Mirroring the present strategy, this means treating the referendum as a case of disobedience and letting security forces to prevent any activities preparing the vote following the orders of the Spanish judiciary.

This would make it difficult for the referendum to be developed normally and could have a negative impact on turnout. Alternatively, Mr Rajoy could seek to prevent the vote using exceptional methods – for example drawing on article 155 of the Spanish Constitution to suspend Catalonia’s political autonomy.

This is a double-edged sword, while it could prevent the referendum, it would also be seen by many Catalans as a disproportionate reaction that would further discredit Spain’s institutions and strengthen the independence cause.

It is unlikely that the deep constitutional crisis in Spain be solved either by appeals to the constitution or by unilateral measures.

The focus on the constitution is unhelpful because this is a political dispute, not a legal one: it is the very concept of a single Spanish nation and sovereignty enshrined in the constitution which is being contested.

At the same time, holding an independence referendum opposed by the full weight of the state and hostage to a boycott by most Catalan unionists is not without problems.

Even if turnout is significant and independence wins comfortably, it is unclear how such a mandate could be implemented unilaterally. If the referendum is a success, the Spanish government will face a serious crisis, which should lead to a new stage of constitutional negotiations. However, that currently looks very unlikely.

Daniel Cetrà is a researcher on nationalism and independence movements at the Centre on Constitutional Change.