The most important political trial in Catalonia’s recent history is about to begin in Madrid. The trial is against members of the former government of Catalonia, the speaker of the Catalan parliament at that time and the leaders of Catalonia’s two largest pro-independence civil society groups.

These individuals will be prosecuted for having organised Catalonia’s referendum on self-determination on 1 October 2017. The charges, brought by the public prosecutor’s office and by the far-right Vox party representing the private accusation, are among the most serious of those envisaged by the Spanish criminal code: rebellion, misappropriation of public funds and civil disobedience.

There are 12 defendants – nine have already spent many months in prison. Four of them have been imprisoned for over one year. They may be sentenced to between 10 and 25 years in jail.

When, in September 2016, I announced to the parliament of Catalonia that the means of resolving the Catalan issue was “a referendum or a referendum”, I was committing myself to two premises that we have observed unfailingly: first, that Catalonia’s fate must be decided by its own citizens through a referendum, and second, that this could only be resolved by peaceful, democratic measures. Not one of the people being prosecuted in this trial, nor any of those in exile, have deviated a millimetre from this commitment.

That referendum was a success in terms of participation, organisation and civically minded behaviour. It was a democratic success and a day that will never be erased from our memories. Around 2.3 million of Catalonia’s 5.3 million registered voters – 43% – took part in the referendum, and 92% of participants backed independence.

People of every age and ideology from every corner of Catalonia came together to make possible something that Spain did not, and does not, want in any way: to ascertain the will of the people about their own future. The chain of solidarity and self-organisation that made the referendum possible was an admirable example of the power that society can wield when faced with a common and shared goal based on the essential values of democracy.

However, despite the civic and peaceful nature of the referendum, and to the dismay of the millions of people who went to vote, the Spanish government decided to turn to violence. Thousands of police officers, sent from various points of Spain, motivated and incited by the cry of “let’s go get them!”, embarked on unprecedented acts of aggression against a peaceful, non-violent civil population. Despite this extraordinary police effort – which cost €90m – neither the ballot boxes could be found nor the referendum prevented. Nevertheless, it left an open wound that will not heal for generations. On top of that, Spain unleashed a wave of repression and threat to our freedoms that continues today, to which the Catalan people have responded in the same way they did in October 2017: calmly, peacefully and democratically. I am convinced that only by closing this open wound and ending the repression will the conditions be created for the resolution of this conflict.

The trial will demonstrate, among other things, that an exercise seen in other parts of the world as perfectly acceptable and praiseworthy – there have been independence referendums for Scotland, Quebec and New Caledonia – is viewed in Spain as a heinous crime. At the same time, it will highlight the fragility of Spanish democracy and the worrying politicisation of the justice system. The main hypothesis is a great fallacy: because the crime of rebellion demands the use of violence, and the violence was only used by the police force, the public prosecutor’s office and the Vox party intend to convince the court that this violence was actually the direct responsibility of the government of Catalonia. This situation is nothing new: on 12 April 1963, a group of priests sent a public letter to Martin Luther King Jr criticising the Birmingham campaign, which fought for human rights and against segregation. On that same day, King was arrested on the charge of having violated the law against demonstrations. From prison he wrote a long letter in response – a paragraph from it serves to illustrate the situation in which all our persecuted and imprisoned colleagues find themselves:

“In your statement you assert that our actions, even though peaceful, must be condemned because they precipitate violence. But is this a logical assertion? Isn’t this like condemning a robbed man because his possession of money precipitated the evil act of robbery? Isn’t this like condemning Socrates because his unswerving commitment to truth and his philosophical inquires precipitated the act by the misguided populace in which they made him drink hemlock? Isn’t this like condemning Jesus because his unique God-consciousness and never-ceasing devotion to God’s will precipitated the evil act of crucifixion? We must come to see that, as the federal courts have consistently affirmed, it is wrong to urge an individual to cease his efforts to gain his basic constitutional rights because the quest may precipitate violence. Society must protect the robbed and punish the robber.”

This trial is a huge mistake that makes a political outcome even more difficult. Replacing political solutions with the criminal code, giving prominence to judges and politicians instead of governments and parliaments, has been one of the colossal errors committed by Spain. At the moment the trial is about to begin, it is essential to send a message to the democrats of the world who are concerned about this authoritarian leaning, and to the people of Catalonia in particular.

Despite the repression, and despite the persistent refusal of Spain to take determined steps towards resolving the conflict, our position remains as resolute as it always has been: to uphold political dialogue, from a standpoint of acknowledgement and mutual respect, as the only way forward in relations between Catalonia and Spain, respectively free and respectively sovereign. Never under any circumstances has violence been an option for us, nor will it ever be – we have been victims of violence and we have suffered from it, but as far as we are concerned peace and non-violence are essential elements of Catalan society, a diverse and harmonious society that is the result of constant migratory processes of which we are the offspring. A society in which those of us who bear responsibility will serve as we always have done: with a sense of loyalty and commitment.

The Catalans are a dignified people and deserve to be treated with dignity – like all the other peoples of the world who are fighting for their sovereignty, to whom we send our fraternal affection.

• Carles Puigdemont is the former Catalan president