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 status, 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 custody and seek reimbursement for related costs.

To ensure compliance, sheriffs must certify their adherence to these requirements annually to the Department of Revenue. 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 data to be reported to the Department of Justice and subsequently 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.