Assembly Bill 24 mandates that county sheriffs in Wisconsin request proof of legal presence from individuals held in county jails for felony offenses. The bill specifies acceptable forms of proof, including U.S. passports, birth records, and various immigration documents. If a sheriff cannot verify an individual's legal presence, they must notify the federal Department of Homeland Security. Additionally, sheriffs are required to comply with detainers and administrative warrants from the federal government regarding individuals in their custody and seek reimbursement for related costs.

To ensure compliance, sheriffs must certify annually to the Department of Revenue that they have adhered to these requirements. Failure to do so will result in a 15% reduction in the county's shared revenue payments for the following year. The bill also requires sheriffs to maintain records of individuals verified as unlawfully present and the crimes for which they were confined, with this information to be reported to the Department of Justice, which will compile and submit a report to the legislature every six months starting in 2027. Furthermore, the bill provides immunity from criminal or civil liability for law enforcement actions taken under these provisions.