An explosive and newly partially unsealed court filing alleges that the US Department of Homeland Security built up dossiers on ICE observers—including their photos, license plate numbers, and other information—and stored them in a system called the Investigative Case Management database, which was built by Palantir.

Palantir did not immediately respond to requests for comment.

A spokesperson for DHS calls the case “meritless” and says that “the underlying lawsuit is based on the lie that there is a database of ‘domestic terrorists’ run by DHS.”Plaintiffs allege in the filing, which is heavily based on documents produced by the government and depositions of DHS agents, that agents had a practice of intimidating protesters and observers. They did this, the filing says, by doing drive-bys of the observers’ homes and, in the case of at least one observer, requiring that she be referred to secondary inspection any time she tries to cross the border until at least January 2027.

"The government is treating people who exercise their First Amendment rights and seek to hold it accountable as criminal suspects, and that's what we're asking the court to stop,” says JoAnna Suriani, an attorney at Protect Democracy who is representing ICE observers in the case.

The filing focuses on agents’ conduct during “Operation Catch of the Day,” an immigration enforcement surge in Maine this past January. It is part of a proposed class action brought in federal court in Maine by four observers: Elinor Hilton, Colleen Fagan, Polyxenia Pantos, and Carlyn Williams. It was filed under seal in September, and a redacted version was made public Friday.

In particular, it describes how one DHS agent, referred to as “Agent J.C.” in the filing, used the Investigative Case Management (ICM) database, which the government describes as the case management system the ICE component Homeland Security Investigations (HSI) uses to document its investigations, to flag observers.

According to the filings, J.C. created ICM records on at least six observers; the government puts the number of people at eight. He labeled two people he filmed at a Home Depot parking lot with “Threat to Law Enforcement, Professional Protestor,” according to the filing, and sent photos of them and others to a US Customs and Border Protection (CBP) officer so he could run a facial recognition search on them using an app called Mobile Query.

On January 20, Pantos briefly watched and photographed an arrest in Portland, Maine, standing a few car lengths away beside their spouse's car. Hours later, per the filing, J.C. ran the car's plate and pulled a report on the owner—Williams—from Accurint, a LexisNexis database for law enforcement, which listed her address, phone numbers, and cohabitants. J.C. then allegedly circulated her photo to his team, asking, “Was this the protestor.”Another agent, per the filing, replied that it didn’t match the woman he had dealt with at the scene; J.C. then told colleagues he was "adding them in ICM now."

According to the legal filing, that afternoon, J.C. called Williams on her cell phone, identifying himself only as "the Department of Homeland Security." According to Williams, he told her she "should encourage" her spouse, Pantos, "not to do anything like that in the future because people who are doing things like that might get added to a domestic terrorism watchlist." J.C. testified in a deposition that he warned Williams she would be arrested if she “continue[d] to do this.”Government attorneys asserted in a court filing that he denied referencing a “domestic terrorism watchlist.”According to documents produced by the government, Williams’ ICM record says that she was theed owner of a vehicle used to “interrupt ICE arrests” and that her driver’s license photo matched a video of "aggressive woman [who] interject[ed] herself into an arrest." According to a 2016 DHS privacy assessment, ICM automatically shares the subject records agents create with CBP’s TECS system, where they act as "lookout records" for screening travelers at the border.

ICM is the system used by HSI agents to create and track case files. ICE awarded Palantir the contract to build ICM in 2014, and the system is built on the company’s Gotham software, which ICE says was customized specifically for operational needs. In 2022, ICE awarded Palantir a new five-year ICM support contract initially valued at up to about $96 million. In 2025, the agency added nearly $30 million to that contract to develop a new platform called “ImmigrationOS.”Todd Lyons, the former acting director of ICE, wrote in an April letter to Rep. Maxwell Frost, the Florida Democrat, that ICE “does not maintain any kind of database of U.S. citizens protesting ICE activities.”He also said DHS isn’t keeping a “separate, standalone database” of people it hasn’t arrested or detained.

The government’s motion to dismiss argues that these were isolated incidents and that DHS policy prohibits this conduct. It says J.C. made records on people he believed were “potential threats to law enforcement” and “did not attempt to nominate any individuals to the terrorist watchlist.”Attorneys for the observers say that DHS’s efforts have had a chilling effect on their First Amendment rights. According to the motion, Pantos stopped all ICE observation work after J.C.’s phone call to Williams, who briefly continued to observe ICE activity and then stopped all together too.

The observers are asking the court to order that Williams’ records be archived, to bar DHS from using the information it collected about the plaintiffs against them, and to prohibit agents in Maine from threatening observers with watchlists or following them to their homes.