Wisconsin Supreme Court Takes Up Case Over County Sheriffs Honoring ICE Detainers

The American Civil Liberties Union brought the lawsuit against five county sheriffs for holding detainees on behalf of ICE.

Immigration and Customs Enforcement agents detain an illegal immigrant near Washington in May 2025. Courtesy of US Immigration and Customs Enforcement

Wisconsin’s highest court is set to decide whether it is legal for local jails to hold detainees at the request of federal immigration authorities.

On Dec. 3, a majority of justices on the Wisconsin Supreme Court voted to take up a lawsuit filed by the American Civil Liberties Union (ACLU) on behalf of Voces de la Frontera, a Milwaukee-based immigrant rights group. They granted the ACLU’s request to hear the case as an original action, allowing it to skip the lower courts entirely.

The court currently has a 4–3 liberal majority. Four justices, who were not identified in the order, voted to accept the case. Conservative Justices Annette Ziegler and Rebecca Bradley dissented.

Justice Brian Hagedorn, who typically sides with the conservative wing, did not disclose how he voted. He wrote separately to explain the court’s review procedures and cautioned that the public should not assume a justice supports an order merely because he or she does not publicly dissent.

The dispute centers on immigration detainers, which are requests from U.S. Immigration and Customs Enforcement (ICE) asking local jails to hold individuals for up to 48 hours beyond the time when they would have otherwise been released. This extra time allows ICE agents to pick up individuals who are suspected of being in the country illegally and pursue deportation.

Wisconsin county sheriffs who choose to honor ICE detainers, the ACLU argued, are violating state law because holding a person beyond his or her release constitutes a “new arrest.” Under state law, they contend, any such arrest must be supported by a judicial warrant issued by a judge based on probable cause.

The lawsuit specifically names the sheriffs of Walworth, Kenosha, Brown, Marathon, and Sauk counties as defendants. According to the ACLU, these counties have carried out the highest number of ICE detainers in the state.

In a joint brief filed in October, attorneys representing the sheriffs defended the practice, arguing that cooperating with federal immigration authorities is well within a county sheriff’s constitutional, statutory, and common-law powers.

“There is no express prohibition in Wisconsin law on Wisconsin sheriffs complying with federal immigration detainers and administrative warrants upon expiration of the state-law bases for detention,” they wrote.

The defense team also emphasized that many of Wisconsin’s law enforcement agencies, including the Brown County Sheriff’s Office, participate in the federal 287(g) program. This partnership deputizes local jail officers to carry out certain immigration enforcement functions on ICE’s behalf.

According to the defense, this program effectively means that detainees wanted by ICE are transferred into federal custody at the moment they would otherwise be released from state custody. As a result, they said, there is no unlawful extension of state detention or any “new arrest.”

Even for those counties lacking 287(g) partnership, the defense argued that when these sheriffs continue to detain someone in response to an ICE detainer, that person is simply “not yet in federal custody” rather than being subject to a new state arrest.

For now, the Supreme Court has directed both sides to submit briefs addressing key questions, including whether a sheriff’s participation in a 287(g) agreement has any effect on the legality of complying with ICE detainers. All briefs are due by Feb. 5, 2026.

The ACLU of Wisconsin welcomed the court’s move to take the case directly.

“Sheriffs are overstepping their authority under Wisconsin law by honoring ICE detainers, regardless of whether they operate under a 287(g) agreement with ICE or not,” Tim Muth, senior staff attorney for the organization, said in a statement.

Samuel Hall, an attorney for the sheriffs, said the defense team is reviewing the Wisconsin Supreme Court’s order and evaluating their next steps in the litigation.

“We are confident, however, that Wisconsin sheriffs who honor ICE detainers do so fully within the bounds of Wisconsin law and the federal legal framework governing immigration enforcement,” Hall said in an emailed statement to The Epoch Times.

Earlier this year, Wisconsin’s Republican-led Assembly passed a bill that would require sheriffs to ask individuals held in jail on felony charges to show proof of legal presence and report them to the U.S. Department of Homeland Security. The bill would also mandate that sheriffs honor ICE detainers, and counties that fail to demonstrate compliance would face reductions in state funding.

The measure never received a vote in the state Senate. But even if it were to clear the Republican-led upper chamber, it would likely be vetoed by Democratic Gov. Tony Evers.