Habeas corpus — the centuries-old legal writ that allows detainees to challenge the legality of their imprisonment — has become a key tool for immigrants swept up in the Trump administration's enforcement sweeps. The petitions, which are public documents, have revealed patterns such as street arrests disproportionately targeting Latinos in New York City, detainees being shuffled across the country just before congressional oversight visits, and a judicial emergency declared in California's Eastern District. But a 2007 amendment to Federal Rule of Civil Procedure 5.2 requires that habeas petitions be filed on paper, not electronically, effectively hiding them from PACER, the federal court's online document system.

"The effect is it takes much longer to get access to these records in a particular case and it makes it basically impossible to get records in a lot of these cases at once," said Renee Griffin, a staff attorney at the Reporters Committee for Freedom of the Press. She called it "a real nationwide problem."

Cronan, who said he has "a PACER account just to look at stuff sometimes," launched Habeas Dockets as a volunteer-run repository. The project crowdsources scanned or photographed petitions from lawyers, journalists, and activists, then uploads them to a searchable online database. "I'm the kind of person who has a PACER account just to look at stuff sometimes," he told Court Watch, which first reported on the effort.

The 2007 rule was originally intended to protect sensitive information such as detainees' medical records, but critics argue it has been applied so broadly that it obscures the workings of the immigration detention system. Roughly 50,000 habeas petitions have been filed in immigration cases since the start of the current administration, according to data compiled by ProPublica. Without centralized digital access, researchers must request paper copies from individual courthouses, a time-consuming and expensive process.

The Habeas Dockets project has already contributed to several investigative reports. Court Watch, which partnered with 404 Media to publish the piece, noted that the records have been used to document racial profiling in street-level ICE arrests and the rapid transfer of detainees to obscure federal facilities.

Some legal experts caution that while the rule creates access barriers, it also guards against misuse of personal information. The rule requires redaction of private details such as Social Security numbers and birth dates, but paper filing makes it harder to verify that redactions are consistent. Volunteers are urged to check filings for unredacted sensitive data before posting.