The Justice Department has filed suit against New Jersey, Gov. Mikie Sherrill, and Attorney General Jennifer Davenport, alleging that the state’s “Law Enforcement Officer Protection Act” unlawfully restricts federal law-enforcement activity. The case, filed in federal court in New Jersey, tees up a direct confrontation over the limits of state power when federal officers operate within state borders.

At the center of the dispute is a familiar constitutional fault line: whether a state may regulate, constrain, or impose conditions on federal officials carrying out federal duties.