CourtSpeak: Supremacy of the Federal Judiciary
Chief Justice John Marshall: “The constitution and laws of a state so far as they are repugnant to the constitution and laws of the United States, are absolutely void. These States are constituent parts of the United States. They are members of one great empire—for some purposes sovereign, for some purposes subordinate. In a government so constituted, is it unreasonable that the judicial power should be competent to give efficacy to the constitutional laws of the legislature? That department can decide on the validity of the Constitution or law of a State, if it be repugnant to the Constitution or to a law of the United States. Is it unreasonable that it should also be empowered to decide on the judgment of a State tribunal enforcing such unconstitutional law? Is it so very unreasonable as to furnish a justification for controlling the words of the Constitution?
“We think it is not. We think that, in a government acknowledgedly supreme, with respect to objects of vital interest to the nation, there is nothing inconsistent with sound reason, nothing incompatible with the nature of government, in making all its departments supreme so far as respects those objects and so far as is necessary to their attainment. The exercise of the appellate power over those judgments of the State tribunals which may contravene the Constitution or laws of the United States is, we believe, essential to the attainment of those objects.”