According to the 48-page lawsuit, the Department of Homeland Security (DHS) and the Department of Justice (DOJ), as well as the heads of both agencies (Attorney General William Barr and acting Homeland Security Secretary Chad Wolf), instituted "a policy that authorized the deployment and operation of federal agents allegedly for the purpose of assuring domestic law and order and tak[ing] over cities."
The move by both agencies was allegedly in response to directives from President Trump beginning "in or around June 2020," the suit stated.
However, it's a claim that DHS says has no merit.
"Dangerous politicians and fringe special interest groups have ginned up a meritless lawsuit," a spokesperson for the department told FOX News in a statement. "Department of Homeland Security have acted entirely lawfully. Instead of condemning the violence we are seeing across the country, these politicians focus on scoring cheap political points to the detriment of the American people."
The Department of Justice declined to comment on pending litigation.
The protest within Oregon's largest city has often devolved into riots and has commonly targeted police and federal buildings and law enforcement.
Meanwhile, police in Oakland have also arrested several protesters in assaults on officers as demonstrations turned increasingly violent.
The suit alleges that the departments used a statute --- which authorizes federal agents to protect federal property and personnel -- to deploy "federal law enforcement to quash civil protests" in both cities and that they approved the "engagement, surveillance, and operations of these deployments to include non-federal property and virtually limitless jurisdiction."
The suit claims the statute was also used to allow agents to erect a fence around the Hatfield Federal Courthouse in Portland "without a permit or City consent." It was also alleged that agents "instituted an unlawful practice in Portland of commandeering control of local law enforcement officers."
The suit further claims the agents were deployed to the cities "either secretly or with little warning."
Police forces in both cities had previously "always been able to expect when and how federal law enforcement agents could assert federal powers within their jurisdictions," attorneys argued in court documents.
"As local governments, Plaintiffs have independent police forces; community relationships; and locally-determined policing policies, practices, and procedures," the suit read.
FOX News' Brie Stimson and FOX Business' Stephanie Pagones contributed to this report.