The Partnership for Civil Justice Fund is suing the Metropolitan Police Department for withholding records related to arrests on Inauguration Day.
The group says acting Police Chief Peter Newsham violated the law by not making the arrest records public.
Since the 2002 World Bank protests in Pershing Park, police are required to maintain and make public records of all mass arrests, as well as records regarding the deployment of chemicals.
The Partnership for Civil Justice Fund says it has done everything it can to obtain the records, including filing a Freedom of Information Act request, but still hasn't received them.
"MPD does not comment on ongoing litigation," a police spokesperson said.
The suit was filed just ahead of the last public meeting on the confirmation of Newsham as chief of police.
"This information is being improperly and illegally withheld at the very moment when its release would inform the public and the D.C. Council in their evaluation of Peter Newsham's nomination to be chief of police," the suit reads.
More than 200 people were charged after protesters smashed the windows of an emergency vehicle and several businesses and set fire to a limousine Jan. 20. Six police officers were hurt, with one falling unconscious after he was hit in the head.
Following the arrest of hundreds at Pershing Park in 2002, D.C. ended up settling for more than $8 million with almost 400 protesters and bystanders who sued over the mass arrests.
The Partnership for Civil Justice Fund litigated that case, in which the court ruled Newsham could be held liable for constitutional rights violations, finding no probable cause for arresting everyone in the park, the lawsuit says.
After the World Bank protest arrests, the D.C. Council legislated the First Amendment Rights and Police Standards Act of 2004. The lawsuit says Newsham and D.C. police are not meeting its public disclosure requirements.