THE SIMPLE concept of complete centralization in the national government of all constitutional powers over international relations is one easily reached and conclusively confirmed. It does not, however, comprise the whole voice of the Constitution, as interpreted by the courts, with respect to international acts, including executive international agreements. While many details of fundamental law and many judicial theories may conceivably come into contact with the exercise of the treaty and executive- agreement powers, there are three doctrines that seem of especial and far-reaching importance in this connection, namely, those connoted by the expressions "states' rights," "due process," and "delegation of power." Of these, the first would seem to have been already disposed of in the preceding chapter, which showed that all power over international intercourse is vested in the national government. Nevertheless some direct discussion of the states' rights doctrine, along with the other two subjects, seems not inappropriate here.
Chief Justice Marshall, in one of his later decisions in the Supreme Court, was specific in holding that states and localities must not encroach upon the national government in the realm of external affairs:
A state is forbidden to enter into any treaty, alliance or confederation. If these compacts are with foreign nations, they interfere with the treaty making power which is conferred entirely on the general government; if with each other, for political purposes, they can scarcely fail to interfere with the general purpose and intent of the constitution. To grant letters of marque and reprisal, would lead directly to war; the power of declaring which is expressly given to congress. . . . It would be tedious to recapitulate the several limitations on the powers of the states. . . They will be found, generally, to restrain state