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.”