The activists argued that "the state is intimidating people from participating in peaceful demonstrations for climate action" by prosecuting protesters.
"We're not allowed to demonstrate, or rather, if you demonstrate for the climate and do it in a disruptive way, you'll be brought to court and most likely convicted of a crime," said Viktor Jonsson, the main plaintiff bringing the case and legal spokesman for the group.
"We can't have that in a democratic society," he told AFP outside the Stockholm district court where the lawsuit was filed.
The complaint was brought by 46 activists from Sweden, Norway and Germany, under the banner "Rosamalet" (The Rosa Case) -- a nod to US civil rights activist Rosa Parks.
They said that between 2020 and 2026, Swedish police, prosecutors and courts had "suspected, prosecuted and in most cases convicted" as many as 388 climate activists for 26 different crimes, including "disobedience, gross unlawful trespassing and sabotage".
The group said in a statement that the "lawsuit includes a large number of examples and testimonies of violations of climate protesters carried out or supported by the Swedish state".
These included "prison sentences, long detentions, arbitrary detentions, violence, torture, threats, calls to commit suicide and secret house searches".
"We demand that the state compensate us for the violations we have been subjected to, because we have been brought to trial," Jonsson said, adding that more activists could potentially join the class action lawsuit later.
Jonsson said the lawsuit was based on Sweden's own constitution, the European Convention on Human Rights and other international human rights texts.
The activists also noted that Sweden home of famed climate campaigner Greta Thunberg and her "Fridays for Future" movement had already been criticised by rights groups and the UN Special Rapporteur on the situation of human rights defenders.
