The question then arose to whom the right of deciding the competency of each court was to be referred.
In nations which constitute a single body politic, when a question is debated between two courts relating to their mutual jurisdiction, a third tribunal is generally within reach to decide the difference; and this is effected without difficulty, because in these nations the questions of judicial competency have no connection with the privileges of the national supremacy.

But it was impossible to create an arbiter between a superior court of the Union and the superior court of a separate State which would not belong to one of these two classes.

It was, therefore, necessary to allow one of these courts to judge its own cause, and to take or to retain cognizance of the point which was contested.

To grant this privilege to the different courts of the States would have been to destroy the sovereignty of the Union de facto after having established it de jure; for the interpretation of the Constitution would soon have restored that portion of independence to the States of which the terms of that act deprived them.

The object of the creation of a Federal tribunal was to prevent the courts of the States from deciding questions affecting the national interests in their own department, and so to form a uniform body of jurisprudene for the interpretation of the laws of the Union.