federation, as all know, has not even answered the purpose of maintaining an alliance. It has never, in any European war, prevented single members of the confederation from allying themselves with foreign powers against the rest. Yet this is the only federation which seems possible among monarchical states. A king, who holds his power by inheritance, not by delegation, and who can not be deprived of it, nor made responsible to any one for its use, is not likely to renounce having a separate army, or to brook the exercise of sovereign authority over his own subjects, not through him, but directly by another power. To enable two or more countries under kingly government to be joined together in an effectual confederation, it seems necessary that they should all be under the same king. England and Scotland were a federation of this description during the interval of about a century between the union of the crowns and that of the Parliaments. Even this was effective, not through federal institutions, for none existed, but because the regal power in both Constitutions was so nearly absolute as to enable the foreign policy of both to be shaped according to a single will. Under the more perfect mode of federation, where every citizen of each particular state owes obedience to two governments, that of his own state and that of the federation, it is evidently necessary not only that the constitutional limits of the authority of each should be precisely and clearly defined, but that the power to decide between them in any case of dispute should not reside in either of the governments, or in any functionary subject to it, but in an umpire independent of both. There must be a Supreme Court of Justice, and a system of subordinate courts in every state of the Union, before whom such questions shall be carried, and whose judgment on them, in the last stage of appeal, shall be final. Every state of the Union, and the federal government itself, as well as every functionary of each, must be liable to be sued in those courts for exceeding their powers, or for non-performance of their federal duties, and must in general be obliged to employ those courts as the instrument for enforcing their federal rights. This involves the remarkable consequence, actually realized in the United States, that a court of justice, the highest federal tribunal, is supreme over the various governments, both state and federal, having the right to declare that any law made, or act done by them, exceeds the powers assigned to them by the federal Constitution, and, in consequence, has no legal validity. It was natural to feel strong doubts, before trial had been made, how such a provision would work; whether the tribunal would have the courage to exercise its constitutional power; if it did, whether it would exercise it wisely, and whether the governments would consent to submit peaceably to its decision. The discussions on the American