The Wisconsin Supreme Court has stepped into the center of a heated legal and political debate by agreeing to hear a case that could reshape how local law enforcement interacts with federal immigration authorities. On December 3, 2025, the court, which currently holds a narrow 4-3 liberal majority, announced it would directly consider whether state law prohibits local jails from detaining individuals at the request of U.S. Immigration and Customs Enforcement (ICE). The case, filed by the immigrant rights group Voces de la Frontera and supported by the American Civil Liberties Union (ACLU) of Wisconsin, challenges the long-standing practice among several county sheriffs of honoring civil detainer requests from ICE.
At the heart of the dispute is the question of whether Wisconsin sheriffs have the legal authority to hold people in jail, sometimes for up to 48 hours beyond their scheduled release, based solely on ICE detainers. These detainers are not criminal warrants, but rather civil requests from federal immigration authorities asking local law enforcement to keep individuals in custody so that ICE agents can take them into federal custody. According to the ACLU, this practice has led to hundreds of people being unlawfully held in jails across the state.
The case is officially titled Voces de la Frontera v Gerber, Wisconsin Supreme Court, No. 2025AP002121. It specifically targets the sheriffs of Walworth, Brown, Kenosha, Sauk, and Marathon counties—jurisdictions identified as having the highest number of ICE detainers in Wisconsin. The ACLU's lawsuit, filed in September 2025, argues that under Wisconsin law, detaining a person beyond their release date without a warrant constitutes a new arrest. "ICE continues to send hundreds of these detainers to Wisconsin jails, and people throughout the state are being illegally held for days so that ICE can pick them up," said Timothy Muth, an attorney for the ACLU of Wisconsin, in a statement reported by Reuters.
The numbers cited in the lawsuit are striking. In the first seven months of 2025 alone, ICE sent over 700 detainers to local jails in Wisconsin, resulting in at least 247 people being held beyond the time they should have been released, according to the ACLU's filings. Most, but not all, Wisconsin sheriffs comply with these detainer requests, which has led to significant controversy and, now, a high-profile legal battle.
Voces de la Frontera, a prominent immigrant rights group, petitioned the Supreme Court to bypass the lower courts, arguing that the issue was of urgent statewide concern. In an order published Wednesday, the court's four-person majority accepted this reasoning, agreeing to take up the case directly. This move itself sparked tension among the justices. Conservative Justices Annette Ziegler and Rebecca Bradley publicly dissented from the decision to hear the case at this stage. Justice Brian Hagedorn, another conservative, wrote separately to caution against the court's "newfound fondness" for taking politically charged cases on an expedited basis, warning that public dissent at this stage could create the impression that "certain justices have settled on a view of the merits prior to briefing."
The legal arguments at stake are complex but have far-reaching implications. The ACLU contends that Wisconsin law largely bars law enforcement from making arrests for civil actions, and that holding someone solely on the basis of an ICE detainer—without a criminal warrant signed by a judge—exceeds the authority of local sheriffs. "A detainer amounts to a new arrest, which needs to be authorized by a warrant that's signed by a judge," the ACLU argued, as reported by Wisconsin Public Radio.
On the other side, the sheriffs have defended their cooperation with ICE, maintaining that their actions are both lawful and consistent with longstanding practices. In an October brief, the sheriffs urged the court not to take up the case, arguing that there was no need to rush or bypass the lower courts. Samuel Hall, an attorney representing four of the sheriffs, said in a statement to Reuters, "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." The sheriffs are currently reviewing the court's order and evaluating their next steps.
The U.S. Department of Homeland Security, which oversees ICE, has not commented publicly on the case. Notably, President Donald Trump's administration, whose immigration policies have been at the center of national debate, has also not weighed in. The issue, however, is hardly unique to Wisconsin. During Trump's first term, state high courts in Massachusetts and Montana, as well as appellate courts in Minnesota and New York, issued rulings that restricted or barred local law enforcement from honoring ICE detainers, arguing that such actions violated state law or constitutional protections.
For immigrant communities and their advocates, the stakes could not be higher. Detainer requests can mean the difference between freedom and days or even weeks of additional detention for people who, in many cases, have already resolved their underlying criminal or civil charges. The ACLU and Voces de la Frontera argue that these extended detentions are not only unlawful but also cause significant harm to individuals and their families, disrupting lives and sowing fear throughout immigrant communities.
For the sheriffs and their supporters, the case raises concerns about public safety and the ability of local law enforcement to cooperate with federal authorities. They argue that honoring ICE detainers is a legitimate tool for addressing immigration violations and maintaining order, and that the current legal framework supports such cooperation. The sheriffs also contend that the ACLU's interpretation of state law is overly restrictive and could undermine efforts to enforce immigration laws.
The broader political context cannot be ignored. Immigration enforcement has been a flashpoint in American politics for years, with sharp divisions between those who favor stricter enforcement and those who advocate for more protections for immigrants. The Wisconsin Supreme Court's decision to take up this case reflects the intensity of the debate and the high stakes involved—not just for the individuals directly affected, but for the broader relationship between state and federal authority in the realm of immigration.
As the case moves forward, Voces de la Frontera has 30 days from the court's order to file a legal brief, after which the defendant sheriffs will have an opportunity to respond. No date for oral arguments has been set yet, but the eyes of the state—and indeed, the nation—will be watching closely. The outcome could have ripple effects far beyond Wisconsin, potentially influencing how other states handle the thorny issue of ICE detainers and local law enforcement cooperation.
For now, the debate continues, with both sides preparing for a legal showdown that could redefine the boundaries of immigration enforcement in Wisconsin and set a precedent for other states grappling with similar challenges.