The US Department of Justice has sued Milwaukee over a city ordinance that bars federal law-enforcement officers from wearing masks while engaging with the public and requires them to display individual identification. The case tests whether a local government can impose such rules on federal agents, particularly those involved in immigration enforcement, or whether federal authority takes precedence.

The DOJ sued the city, Mayor Cavalier Johnson, City Attorney Evan Goyke and Police Chief Jeffrey Norman, arguing the ordinance unlawfully regulates federal operations and endangers officers by exposing them to harassment or doxxing. Milwaukee’s rule took effect in April and applies to law-enforcement personnel, including federal officers; the city attorney had declined the DOJ’s earlier demand to exempt federal agents from enforcement.