Distinctions between citizens solely because of their ancestry are, by their very nature, odious to a free people whose institutions are founded upon the doctrine of equality. For that reason, legislative classification or discrimination based on race alone has often been held to be a denial of equal protection. We may assume that these considerations would be controlling here were it not for the fact that the danger of espionage and sabotage, in time of war and of threatened invasion, calls upon the military authorities to scrutinize every relevant fact bearing on the loyalty of populations in the danger areas. Because racial discriminations are in most circumstances irrelevant, and therefore prohibited, it by no means follows that, in dealing with the perils of war, Congress and the Executive are wholly precluded from taking into account those facts and circumstances which are relevant to measures for our national defense and for the successful prosecution of the war, and which may, in fact, place citizens of one ancestry in a different category from others. . . .

The adoption by Government, in the crisis of war and of threatened invasion, of measures for the public safety, based upon the recognition of facts and circumstances which indicate that a group of one national extraction may menace that safety more than others, is not wholly beyond the limits of the Constitution, and is not to be condemned merely because, in other and in most circumstances, racial distinctions are irrelevant. Here, the aim of Congress and the Executive was the protection against sabotage of war materials and utilities in areas thought to be in danger of Japanese invasion and air attack. We have stated in detail facts and circumstances with respect to the American citizens of Japanese ancestry residing on the Pacific Coast which support the judgment of the war-waging branches of the Government that some restrictive measure was urgent. We cannot say that these facts and circumstances, considered in the particular war setting, could afford no ground for differentiating citizens of Japanese ancestry from other groups in the United States. The fact alone that attack on our shores was threatened by Japan, rather than another enemy power, set these citizens apart from others who have no particular associations with Japan.

Our investigation here does not go beyond the inquiry whether, in the light of all the relevant circumstances preceding and attending their promulgation, the challenged orders and statute afforded a reasonable basis for the action taken in imposing the curfew. We cannot close our eyes to the fact, demonstrated by experience, that, in time of war, residents having ethnic affiliations with an invading enemy may be a greater source of danger than those of a different ancestry. Nor can we deny that Congress, and the military authorities acting with its authorization, have constitutional power to appraise the danger in the light of facts of public notoriety. We need not now attempt to define the ultimate boundaries of the war power. We decide only the issue as we have defined it—we decide only that the curfew order as applied, and at the time it was applied, was within the boundaries of the war power. In this case, it is enough that circumstances within the knowledge of those charged with the responsibility for maintaining the national defense afforded a rational basis for the decision which they made. Whether we would have made it is irrelevant.

Source: Hirabayashi v. United States, 320 U.S. 81 (1943).