Hines, Secretary of Labor & Industry of Pennsylvania v. Davidowitz
United States Supreme Court
312 U.S. 52 (1941)
Pennsylvania's 1939 Alien Registration Act required non-citizens 18 or older to register annually, pay a fee, and carry a registration card, while Congress's 1940 federal Alien Registration Act required non-citizens 14 or older to register and provide personal information to the federal government. Davidowitz (plaintiff) sued to enjoin Hines (defendant), Pennsylvania's Secretary of Labor & Industry, from enforcing the state law as preempted by the federal statute; a three-judge district court panel agreed, and Pennsylvania appealed to the Supreme Court.
Whether federal law governing the registration of non-citizens may occupy an entire field such that any state law in that same field is preempted, even absent express preemption language.