The city of Washington DC has sued far-right groups the Proud Boys and Oath Keepers, seeking to collect on the financial costs of the deadly 6 January attack on the US Capitol and its aftermath.
The suit aims to hold accountable two groups that prosecutors say played a leading role in an assault by thousands of supporters of then-President Donald Trump that aimed to prevent Congress from certifying Democrat Joe Biden's election victory.
District of Columbia Attorney General Karl Racine told reporters the defendants had caused physical and financial harm to Washington and its residents, adding that the city will seek "severe" financial penalties against the defendants.
"Our intent is to hold these violent mobsters and these violent hate groups accountable and to get every penny of damage we can," he said at a news conference.
The lawsuit will seek to recover the costs of deploying roughly 1,100 city police officers to bolster other police forces who defended the Capitol against the attack, which it says amounts to millions of dollars.
District of Columbia Attorney General Karl Racine Source: Getty Images North America
It also sought to recover medical and paid-leave costs incurred afterward for the more than 65 officers injured during the assault and the more than 1,000 who have sought therapy since.
The suit also included civil assault and battery charges against the two organisations, along with 30 named and 50 unnamed people it alleges were involved in the riot.
The lawsuit opened up another legal front against alleged participants in the 6 January attack.
Four people died and hundreds were injured during the multi-hour onslaught, and one police officer died the next day of injuries sustained while defending Congress. Four officers who were at the Capitol that day have since taken their own lives.
Prosecutors have filed conspiracy charges against some members of the Oath Keepers and the Proud Boys, saying they planned the attack in advance and were in the vanguard of the assault.
"The result of that planning, the January 6th Attack on the Capitol, was not a protest or a rally. It was a coordinated act of domestic terrorism," the suit says.
Nearly 700 people overall have faced criminal charges stemming from the event.
The lawsuit invoked the Ku Klux Klan Act of 1871, which allows people to sue for civil rights violations.
The law has been used to target the Klan and other extremist groups - most recently last month, when a jury found the organizers of a 2017 white supremacist rally in Charlottesville, Virginia, liable for $26 million USD in damages.
The lawsuit does not name Mr Trump or former members of his administration as defendants.
Members of Congress and several police officers who defended the Capitol have also filed separate lawsuits against the two groups, charging that they conspired with Mr Trump to launch the attack.
It was not clear whether the two groups are in a position to defend themselves, or whether the lawsuit will yield any financial penalties.
Lawyers defending several of those named in the lawsuit did not immediately respond to a request for comment.
Mr Racine and other district officials said they hoped it would also serve as a warning to deter similar behaviour by other extremist groups.
"If we don't get a penny in restitution, this lawsuit's deterrent effect will say, 'Be prepared to spend money, because we are coming after you,'" said Eleanor Holmes Norton, who represents the District in the House of Representatives.
