The supremacy of the Federal Government, when operating within its constitutional sphere, over all persons and bodies politic within its territorial limits, is no longer opens to question. That the extent of this federal constitutional sphere of action is to be determined in the last resort by the federal Supreme Court is equally well settled.

The maintenance of this supremacy unimpaired, while at the same time preserving to the States their proper autonomy and independence of action, has, however, been a difficult task; and, so long as the federal form is retained, this task will continue to tax to the utmost the legal and political abilities of our courts and political bodies. With a quite proper motive those who have controlled the public actions of the States, and those who have guided the activities of the United States, have sought for their respective governments the greatest possible constitutional power and independence, and, therefore, have not hesitated to occupy debatable territory. Thus, without there being any denial of the supremacy of the federal law, when operating within its proper field, or of the right of the federal Supreme Court to determine, in final resort, the extent of that proper field, frequent conflicts have resulted. These conflicts in their many and varied forms furnish much of the material for the present treatise, and they will be severally considered in their logical order. It will not be without value, however, to review in this introductory chapter some of the more important cases in which the supremacy of federal over state law has been generally and broadly asserted.

The general statement may be made that, since the beginning of our present Government, in no instance has the federal Supreme Court failed to assert the supremacy of the federal power when the States attacked its authority ha3. In 1793 the court upheld its