Immigrant Advocates and ACLU Challenge Marathon County ICE Detainers

(MARATHON COUNTY, WISCONSIN) Immigrant advocates and civil liberties attorneys are asking Wisconsin’s highest court to end the practice of local jails holding people at the request of federal immigration agents, saying the policy in Marathon County and elsewhere violates state law and harms public safety. On November 5, 2025, the ACLU of Wisconsin filed a petition with the Wisconsin Supreme Court on behalf of Voces de la Frontera, naming Marathon County Sheriff Chad Billeb and four other sheriffs as respondents, and seeking a statewide ruling that county sheriffs cannot detain people beyond their scheduled release based on immigration holds known as ICE detainers.

The legal challenge lands amid a sharp rise in federal requests to Wisconsin jails. According to figures cited by the groups, U.S. Immigration and Customs Enforcement sent more than 700 detainer requests to facilities across the state in the first seven months of 2025. Those requests ask local authorities to keep a person in jail for an extra 48 hours after they would otherwise be released so that federal agents can take custody. The ACLU and Voces de la Frontera say that in Marathon County, the sheriff’s cooperation with ICE detainers exposes residents to unlawful detention and sows distrust, especially among immigrant communities who already feel targeted by federal enforcement.

At the heart of the case is a straightforward but high-stakes legal question: whether an ICE detainer is enough under Wisconsin law to justify keeping someone in jail once they have posted bond, completed a sentence, or had charges dropped. The ACLU argues it is not, because detainers rely on administrative immigration documents rather than judicial warrants.

“ICE calls these warrants,” said Hannah Schwarz, ACLU of Wisconsin attorney. “We do not consider them warrants. Under Wisconsin state law, a warrant is something issued by a court or a judge. That is not happening here.”
Schwarz’s remark underscores the ACLU’s position. If the court agrees, sheriffs could be barred from using ICE detainers to prolong detention, reshaping how local agencies across the state respond to federal immigration requests.

The petition underscores how the process works in practice. When a Wisconsin jail receives a detainer, it is an administrative notice—often accompanied by a form bearing an ICE officer’s signature—asking the jail to hold a person up to 48 hours beyond the time they would lawfully walk free. In Marathon County and other jurisdictions, advocates say the hold frequently kicks in after a person posts bail or resolves their case, turning what would have been release into prolonged confinement. The lawsuit argues that this extra time amounts to a new arrest that, under Wisconsin law, requires a judicial warrant based on probable cause—something an ICE administrative detainer does not provide.

For immigrant families in Marathon County, the stakes are immediate. Advocates describe people who, after traffic stops or minor citations, spend unexpected days in jail while ICE decides whether to pick them up. Christine Neumann-Ortiz, executive director of Voces de la Frontera, said this kind of cooperation breaks trust with local law enforcement and spreads fear through neighborhoods where residents already worry that routine encounters could trigger deportation.

“The unlawful collaboration between local law enforcement and ICE destabilizes communities and erodes trust in law enforcement. (It) has a chilling effect on victims and the vulnerable who might otherwise seek help from the police.”
She added:
“The US Constitution extends protections to all people living in the U.S, regardless of immigration status. The notion that immigrants can be denied those rights is offensive and unlawful. Too often, simply driving without a license or committing other minor infractions can lead to prolonged detention, deportation, family trauma, and separation.”

The petition names Sheriff Chad Billeb because of his office’s role in Marathon County, where ACLU Wisconsin says honoring ICE detainers has led to people being held after their criminal cases would otherwise allow release. Billeb declined to comment on the lawsuit, citing its pending status. Across the state, the ACLU contends that detainer-based holds have become routine even for relatively low-level cases, with some sheriffs continuing to hold individuals after bond posting or charges being dropped. Those extra hours, the groups argue, are time no judge has ordered and can tip the balance toward a transfer to immigration custody, starting a process that separates families and drives people deeper into the shadows.

Attorneys for ACLU Wisconsin frame their argument not as a challenge to federal immigration authority, but as a question of what state law permits local officers to do.

“We believe that state and local law enforcement are overstepping their authority under Wisconsin law by honoring ICE detainers, regardless of whether they operate under a 287(g) agreement with ICE that purports to delegate certain immigration enforcement powers to local law enforcement. This is an important issue that must be addressed quickly, as our immigrant neighbors are living in fear and constantly at risk of being unlawfully held and apprehended by ICE,” said Tim Muth, senior staff attorney with the ACLU of Wisconsin.
The reference to 287(g) points to a federal program in which ICE can train and authorize certain local officers to carry out immigration duties, but the ACLU argues that even such agreements cannot override state rules that require judicial approval for arrests.

The ACLU’s filing also leans on a recent report by the organization, which concludes that local law enforcement in parts of Wisconsin maintains close ties with ICE and that these links drive arrests, transfers, and deportations by way of county jails. The report characterizes some of these partnerships as “feeding the deportation machine to make money,” arguing that local agencies use ICE’s demand for beds and holds to justify detention practices that generate fees or reimbursements. While the lawsuit focuses on legal authority under Wisconsin statutes, the broader critique reaches into how detainers change the role of city and county officers, turning routine policing into a pipeline for federal immigration enforcement.

In Marathon County, where industries depend on immigrant labor and families span multiple statuses, community groups say ICE detainers deter people from reporting crimes, attending court, or seeking help in emergencies. Advocates point to the “chilling effect” on victims of domestic violence and wage theft who worry that any contact with police could land them in jail—and then in ICE custody. Those fears, they say, ripple beyond noncitizens with pending cases to their U.S. citizen children, spouses, and neighbors, who shoulder the shock of sudden separation and the financial burden of legal fees, bail costs, and lost wages.

The legal stakes are heightened by the volume of federal requests this year. More than 700 ICE detainers in seven months is a substantial stream into county jails statewide, and the Milwaukee-based rights group argues Marathon County is a major node in that network. ACLU Wisconsin emphasizes that these requests are not court warrants and do not carry the probable-cause findings state law requires for an arrest. If the Wisconsin Supreme Court holds that honoring them amounts to a new arrest, sheriffs would be forced to turn down detainers absent a judge’s order, reshaping how agencies handle the 48-hour window ICE seeks.

The political backdrop in Madison is tense. Earlier this year, the GOP-controlled Assembly passed a bill that would penalize counties that decline to honor these federal requests, withholding funds as leverage to force compliance. Republican sponsors argued the policy is necessary for public safety, casting local noncooperation as a risk to communities if people charged with crimes are released rather than held for ICE pickup. The measure is expected to be vetoed by Democratic Governor Tony Evers, who has opposed attempts to require local cooperation with federal immigration enforcement. For Marathon County, the bill underscored a deepening split between statehouse Republicans who want uniform compliance with ICE detainers and community advocates who say local leaders should not be pressed into federal service.

The Supreme Court petition seeks to move the dispute out of the political arena and into a clear legal framework that applies statewide. If the court agrees to hear the case, it could deliver a ruling that sets a uniform rule for sheriffs from Marathon County to the state’s southern border. The petitioners argue the court should act quickly because the current practice exposes people to illegal confinement each day, and because the legal question—whether administrative detainers meet Wisconsin’s standard for arrest—is squarely within the court’s purview.

Immigrant advocates describe their legal drive as a response to the way ICE detainers reshape everyday justice in Wisconsin’s counties. In their telling, the practice severs the clean line between completing a sentence or posting bond and walking out of jail. Instead, that moment of release can be replaced by hours of uncertainty, with detention extended not for a new crime or a judge’s order, but for a federal request signed by an immigration officer. The difference matters, they say, because it determines whether people are free to return to work, care for children, appear for scheduled court dates, and consult counsel—or whether they are confined while a federal agency decides what to do next.

Marathon County’s role in the lawsuit underscores how this debate is playing out beyond the state’s largest cities. Community groups say small towns and rural counties have significant numbers of immigrant workers in factories, dairy farms, meat processing, and service jobs. In those areas, a traffic stop or workplace inspection can lead to a jail booking, followed by an ICE detainer, and then a transfer to immigration custody far from home. The ACLU and Voces de la Frontera argue that the legal machinery of detainers magnifies the consequences of minor infractions, and they want the Wisconsin Supreme Court to draw a firm line that requires judicial oversight for any continued detention.

ICE, for its part, maintains that detainers are a key public safety tool that allows the agency to take custody of individuals who may be removable under federal law without releasing them back into communities. The agency posts information about detainers and related processes on its official site, including explanations of how local law enforcement is asked to notify ICE and maintain custody for up to 48 hours to facilitate transfer. Readers can find ICE’s description of detainers at this ICE detainers information page. The ACLU’s petition does not dispute ICE’s federal role but insists that Wisconsin sheriffs must follow state standards requiring court-issued warrants for arrests.

As the case moves forward, practical questions loom for Marathon County and other sheriffs named in the petition. If the court issues a temporary order constraining detainers while it considers the merits, jails would need to adjust booking and release procedures quickly, and ICE would have to coordinate arrests outside jail settings. If the court declines to take the case immediately, the lawsuit signals that similar challenges could surface in lower courts, potentially creating a patchwork of rulings. For now, the petitioners say their goal is to secure a clear, statewide answer and end what they describe as prolonged detention based solely on administrative paperwork.

For families in Marathon County, advocates say the human calculus is stark: more time in custody means missed paychecks, canceled childcare, and mounting bills, with the added fear of transfer to out-of-state immigration detention if ICE takes custody. That anxiety, they argue, suppresses cooperation with police, discourages crime reporting, and erodes the witness testimony prosecutors rely on. For the ACLU of Wisconsin, those knock-on effects are part of the legal argument: when a county jail holds someone beyond their lawful release, the action must meet state standards, not just federal requests. The petition tells the justices that line is currently being crossed.

Backers of the Assembly bill counter that failing to honor ICE detainers puts communities at risk by allowing potentially dangerous individuals to be released rather than handed over to federal agents. Advocates respond that criminal courts already weigh risk when granting bail or imposing sentences and that state law—not federal forms—should control whether a sheriff can keep someone behind bars. With pressure rising from both sides, the Wisconsin Supreme Court’s decision on whether to take up the case could become the defining moment of the debate.

Schwarz’s plain-spoken summary of the warrant dispute captures the core claim the justices have been asked to decide.

“ICE calls these warrants,” she said. “We do not consider them warrants. Under Wisconsin state law, a warrant is something issued by a court or a judge. That is not happening here.”
Neumann-Ortiz framed the stakes in human terms—fear, trust, and the Constitution’s promise of equal protection—while Muth underscored urgency for those “living in fear and constantly at risk of being unlawfully held and apprehended by ICE.” Between Marathon County’s cooperation with ICE detainers and the ACLU’s statewide legal push, the next move now rests with the state’s highest court and its answer to whether a federal request can stand in for a judge’s order inside Wisconsin’s jails.