The last element of the concept of Federalism to demand attention is the doctrine that the National Government is a government of enumerated powers only, and consequently under the necessity at all times of justifying its measures juridically by pointing to some particular clause or clauses of the Constitution which, when read separately or in combination, may be thought to grant power adequate to such measures. In spite of such recent decisions as that in United States _v._ Darby, this time-honored doctrine still guides the authoritative interpreters of the Constitution in determining the validity of acts which are passed by Congress in presumed exercise of its powers of domestic legislation--the course of reasoning pursued by the Chief Justice in the Darby Case itself is proof that such is the fact. In the field of foreign relations, on the contrary, the doctrine of enumerated powers has always had a difficult row to hoe, and today may be unqualifiedly asserted to be defunct. As early as the old case of Penhallow _v._ Doane, which was decided by the Supreme Court in 1795, certain counsel thought it pertinent to urge the following conception of the War Power: A formal compact is not essential to the institution of a government. Every nation that governs itself, under what form soever, without any dependence on a foreign power, is a sovereign state. In every society there must be a sovereignty. 1 Dall. Rep. 46, 57. Vatt. B. 1. ch. 1. sec. 4. The powers of war form an inherent characteristic of national sovereignty; and, it is not denied, that Congress possessed those powers....[23] To be sure, only two of the Justices felt it necessary to comment on this argument, which one of them endorsed, while the other rejected it. Yet seventy-five years later Justice Bradley incorporated closely kindred doctrine into his concurring opinion in the Legal Tender Cases;[24] and in the years following the Court itself frequently brought the same general outlook to questions affecting the National Government's powers in the field of foreign relations. Thus in the Chinese Exclusion Case, decided in 1889, Justice Field, in asserting the unlimited power of the National Government, and hence of Congress, to exclude aliens from American shores, remarked: While under our Constitution and form of government the great mass of local matters is controlled by local authorities, the United States, in their relation to foreign countries and their subjects or citizens, are one nation, invested with the powers which belong to independent nations, the exercise of which can be invoked for the maintenance of its absolute independence and security throughout its entire territory.[25] And four years later the power of the National Government to deport alien residents at the option of Congress was based by Justice Gray on the same general reasoning.[26]