Article I, Section 8, Clause 11:
[The Congress shall have Power . . .] To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; . . .
To some indeterminate extent, the power to wage war embraces the power to prepare for it and the power to deal with the problems of adjustment following its cessation. Justice Story emphasized that
[i]t is important also to consider, that the surest means of avoiding war is to be prepared for it in peace. . . . How could a readiness for war in time of peace be safely prohibited, unless we could in like manner prohibit the preparations and establishments of every hostile nation? . . . It will be in vain to oppose constitutional barriers to the impulse of self-preservation. 1 Authoritative judicial recognition of the power is found in Ashwander v. TVA, 2 upholding the power of the Federal Government to construct and operate a dam and power plant, pursuant to the National Defense Act of June 3, 1916. 3 The Court noted that the assurance of an abundant supply of electrical energy and of nitrates, which would be produced at the site,
constitute national defense assets, and the project was justifiable under the war powers. 4
Perhaps the most significant example of legislation adopted pursuant to the war powers when no actual
shooting war was in progress was the Atomic Energy Act of 1946, establishing a body to oversee and further the research into and development of atomic energy for both military and civil purposes. 5 Congress has also authorized a vast amount of highway construction, pursuant to its conception of their
primary importance to the national defense, 6 and the first extensive program of federal financial assistance in the field of education was the National Defense Education Act. 7 These measures, of course, might also be upheld under the power to spend for the
common defense. 8 The post-World War II years, though nominally peacetime, constituted the era of the Cold War and the occasions for several armed conflicts, notably in Korea and Indochina, in which the Congress enacted much legislation designed to strengthen national security, including an apparently permanent draft, 9 authorization of extensive space exploration, 10 authorization for wage and price controls, 11 and continued extension of the Renegotiation Act to recapture excess profits on defense contracts. 12 Additionally, the period saw extensive regulation of matter affecting individual rights, such as loyalty-security programs, 13 passport controls, 14 and limitations on members of the Communist Party and associated organizations, 15 all of which are dealt with in other sections.
Other legislation is designed to effect a transition from war to peace. The war power
is not limited to victories in the field. . . . It carries with it inherently the power to guard against the immediate renewal of the conflict, and to remedy the evils which have arisen from its rise and progress. 16 This principle was given a much broader application after the First World War in Hamilton v. Kentucky Distilleries, Co., 17 where the War Time Prohibition Act 18 adopted after the signing of the Armistice was upheld as an appropriate measure for increasing war efficiency. The Court was unable to conclude that the war emergency had passed with the cessation of hostilities. 19 But in 1924, it held that a rent control law for the District of Columbia, which had been previously upheld, 20 had ceased to operate because the emergency which justified it had come to an end. 21
A similar issue was presented after World War II, and the Court held that the authority of Congress to regulate rents by virtue of the war power did not end with the presidential proclamation terminating hostilities on December 31, 1946. 22 However, the Court cautioned that
[w]e recognize the force of the argument that the effects of war under modern conditions may be felt in the economy for years and years, and that if the war power can be used in days of peace to treat all the wounds which war inflicts on our society, it may not only swallow up all other powers of Congress but largely obliterate the Ninth and Tenth Amendments as well. There are no such implications in today's decision. 23
In the same year, the Court sustained by only a five-to-four vote the Government's contention that the power which Congress had conferred upon the President to deport enemy aliens in times of a declared war was not exhausted when the shooting stopped. 24
It is not for us to question, said Justice Frankfurter for the Court,
a belief by the President that enemy aliens who were justifiably deemed fit subjects for internment during active hostilites [sic] do not lose their potency for mischief during the period of confusion and conflict which is characteristic of a state of war even when the guns are silent but the peace of Peace has not come. 25