A mass trial of 47 lawyers, doctors, psychologists and political activists began and ended in 25 minutes in Madrid on Monday. A plea deal allowed the accused to avoid sentences of up to 20 years on charges of membership of the now-dissolved armed separatist group Eta.

Defendants agreed to a deal that recognised the charges against them, but which will see the majority of defendants sentenced to suspended sentences of two years each, while two others face jail time of five months.

The abrupt resolution took place on the first day of the trial at Madrid’s audiencia nacional, and came as verdicts were expected in the mass trial of 12 Catalan separatist politicians next month. Similar plea deals were also reached in two trials of Basque political activists in January and April 2016.

Prosecutors in the latest Basque case had argued that the 47 accused were members of a network called koordinazioa taldea, or coordination group, which the state alleged constituted a key part of Eta’s overall strategy. They faced charges that they formed part of Eta’s “prison front”, alongside other allegations such as financing terrorism.

The defendants and their supporters had maintained the terrorism allegations were an attempt to criminalise people who advocate for the human rights of Basque political prisoners, fugitives, their families and those affected by state violence, such as victims of torture.

After a bloody five-decade conflict with the Spanish state, Eta declared a permanent ceasefire in 2011 and formally announced its complete dissolution in 2018, declaring the pursuit of purely political means for its goal of an independent, socialist Basque country.

Several hundred Basque political prisoners remain in jail, with others living as fugitives outside Spain.

One of the defendants, Amaia Izko, was arrested along with other lawyers in February 2015 as she tried to enter the audiencia nacional – the Spanish court responsible for accusations of terrorism and organised crime – to work on a mass trial of Basques accused of terrorism. She faced nine years in prison accused of membership of Eta.

Speaking outside the court after the trial ended, Izko explained that the 47 defendants had taken a collective decision to accept the deal.

She said two defendants, Arantza Zulueta and Jon Enparantza, had taken “the responsible decision to sacrifice themselves to make this outcome possible” and now faced five months in prison, accused of being in leadership roles.

Speaking to the Guardian before the trial, Izko said: “We’re standing here accused of terrorism, with some of us, as lawyers, accused based on the practice of our profession and our defence of cases like this.

“There’s a feeling that the state is getting revenge on us for the work we’ve done as lawyers in condemning the lack of legal guarantees in the audiencia nacional, in condemning cases of solitary confinement and cases of torture.”

The audiencia nacional has long faced accusations of being a political court, due in part to its birth as the successor to the public order tribunal of the fascist dictator Francisco Franco’s regime, the fact its judges are political appointees and its role in investigating and trying politically controversial cases.

In this trial, Izko and others saw a politically motivated attempt by the Spanish state to “criminalise solidarity” and to “hinder the peace process and the political normalisation and coexistence which started in the Basque country” after the ceasefire and dissolution of Eta.

The trial is the result of a wave of arrests in 2013, 2014 and 2015, which targeted five separate groups working on behalf of Basque political prisoners, fugitives and their families.

Among those facing terrorism charges were 18 members of Herrira, a collective which campaigns for the rights of Basque prisoners and fugitives; 12 lawyers who have defended Basque political prisoners, including those accused of Eta membership; eight people who worked as mediators between Basque political prisoners and Basque civil society; two members of Etxerat, an organisation of family members of Basque political prisoners; and two members of Jaiki Hadi, a collective of medical professionals who support current and former prisoners, their families and victims of torture by the Spanish state.

Iker Urbina, one of the 11 lawyers defending the 47, argued that the prosecution’s accusation of terrorism was not only politically motivated but also legally inconsistent, as all accusations related to activity from 2012.

“The acts which the defendants are accused of happened after ETA publicly declared the cessation of its armed activities in 2011 … and had already expressed its willingness to disappear,” he said.

An estimated 50,000 people marched in Bilbao on Saturday to express solidarity with the defendants. “This expression of solidarity has been incredibly important to allow for this agreement. There’s been incredible support,” said the Basque journalist Patxi Gaztelumendi.