ICE Warns Cook County Sheriff of Potential Witness Tampering Charges Over Immigration Subpoenas

U.S. Immigration and Customs Enforcement has warned Cook County Sheriff Tom Dart that failure to facilitate compliance with immigration subpoenas for jail inmates could constitute federal witness tampering, escalating a long-running dispute over sanctuary policies in the Chicago area.

In a series of letters delivered in July 2026, ICE officials accompanying subpoenas for four individuals held at Cook County Jail stated that not allowing the inmates to appear for interviews or be produced upon release “may constitute Tampering with a Witness” under federal law. The letters, signed by assistant field office directors and obtained through public records requests, referenced potential fines and imprisonment for noncompliance. One letter specifically directed the sheriff’s office to bring a named inmate before a deportation officer at an ICE facility or produce the person at the time of release.

Three of the four individuals named in the subpoenas had already been released from custody by the time the documents reached the sheriff’s office. The office provided the remaining inmate with the subpoena. A spokesperson for Sheriff Dart confirmed receipt of the materials and stated that the office cannot release individuals in custody for interviews with other agencies or transfer them solely on the basis of civil immigration requests.

Cook County operates under the Illinois TRUST Act and local ordinances that limit cooperation with federal immigration authorities on civil matters. These policies generally prohibit holding inmates beyond their criminal cases or granting ICE access without a judicial criminal warrant. Dart, a Democrat who oversees the largest jail in the Midwest, has long maintained that his office prioritizes public safety within the bounds of state law and does not honor routine ICE detainers for civil immigration enforcement.

The Department of Homeland Security described the letters as an effort to compel “sanctuary politicians” to stop releasing individuals sought for deportation, particularly those with criminal histories. Similar warnings were issued to Hennepin County Sheriff Dawanna Witt in Minnesota, indicating a broader approach toward jurisdictions that restrict ICE access to jails.

The dispute builds on prior scrutiny of Cook County’s practices. In a May 2026 letter, House Judiciary Committee Chairman Jim Jordan and Immigration Subcommittee Chairman Tom McClintock criticized the sheriff’s office for ignoring ICE detainers, citing cases in which individuals with prior convictions—including child-related offenses—were released and later faced new criminal charges. Data referenced by federal officials and congressional letters have linked Illinois sanctuary policies to the release of nearly 2,000 noncitizens with criminal records over a period of less than a year in 2025.

No criminal charges have been filed against Dart. Legal observers have noted that successfully prosecuting a witness-tampering case under these circumstances would face significant hurdles, as the statute typically requires proof of corrupt intent to obstruct a federal proceeding. The sheriff’s office has maintained that its actions comply with state law restricting civil immigration cooperation.

The exchange marks a notable intensification in federal efforts to secure access to inmates in sanctuary jurisdictions amid the Trump administration’s expanded immigration enforcement priorities. Cook County Jail continues to process large numbers of detainees, and the outcome of the subpoena process remains unresolved as both sides hold to their legal positions.