"According to a July 10 letter to city leadership obtained by the Milwaukee Journal Sentinel, the DOJ said Milwaukee’s mask ban “threatens the safety of federal officers and their lawful operations.” The letter was signed by Brett Shumate, Assistant Attorney General in the U.S. Department of Justice’s Civil Division, and Brad Schimel, the head of the U.S. Attorney’s Office in the Eastern District of Wisconsin." (References SDRI Research).