Hines v. Davidowitz
In Hines v. Davidowitz, 312 U.S. 52 (1941), the U.S. Supreme Court inferred an intent to pre-empt from the dominance of the federal interest in foreign affairs because "the supremacy of the national power in the general field of foreign affairs ... is made clear by the Constitution," id., at 62, and the regulation of that field is "intimately blended and intertwined with responsibilities of the national government," id., at 66. See also Zschernig v. Miller, 389 U.S. 429, 440-441 (1968).
This case involved the validity of an Alien Registration Act adopted by the Commonwealth of Pennsylvania. The Act, passed in 1939, requires every alien 18 years or over, with certain exceptions, to register once each year; provide such information as is required by the statute, plus any "other information and details" that the Department of Labor and Industry may direct; pay $1 as an annual registration fee; receive an alien identification card and carry it at all times; show the card whenever it may be demanded by any police officer or any agent of the Department of Labor and Industry; and exhibit the card as a condition precedent to registering a motor vehicle in his name or obtaining a license to operate one. The Department of Labor and Industry was charged with the duties of classifying the registrations for "the purpose of ready reference," and furnishing a copy of the classification to the Pennsylvania Motor Police. Nonexempt aliens who fail to register are subject to a fine of not more than $100 or imprisonment for not more than 60 days, or both. For failure to carry an identification card or for failure to show it upon proper demand, the punishment is a fine of not more than $10, or imprisonment for not more than 10 days, or both.