...the particular phraseology of the Constitution of the United States confirms and strengthens the principle, supposed to be essential to all writte… - John Marshall

This great principle is that the Constitution and the laws made in pursuance thereof are supreme; that they control the Constitution and laws of the respective States, and cannot be controlled by them. From this, which may be almost termed an axiom, other propositions are deduced as corollaries, on the truth or error of which, and on their application to this case, the cause has been supposed to depend. These are, 1st. That a power to create implies a power to preserve; 2d. That a power to destroy, if wielded by a different hand, is hostile to, and incompatible with these powers to create and to preserve; 3d. That, where this repugnancy exists, that authority which is supreme must control, not yield to that over which it is supreme.

It has been said, that the people had already surrendered all their powers to the State sovereignties, and had nothing more to give. But, surely, the question whether they may resume and modify the powers granted to government does not remain to be settled in this country. Much more might the legitimacy of the general government be doubted, had it been created by the States. The powers delegated to the State sovereignties were to be exercised by themselves, not by a distinct and independent sovereignty, created by themselves. To the formation of a league, such as was the confederation, the State sovereignties were certainly competent. But when, "in order to form a more perfect union," it was deemed necessary to change this alliance into an effective government, possessing great and sovereign powers, and acting directly on the people, the necessity of 'referring it to the people, and of deriving its powers directly from them, was felt and acknowledged by all.

It is emphatically the province and duty of the judicial department to say what the law is. Those who apply the rule to particular cases, must of necessity expound and interpret that rule. If two laws conflict with each other, the courts must decide on the operation of each. So if a law be in opposition to the constitution: if both the law and the constitution apply to a particular case, so that the court must either decide that case conformably to the law, disregarding the constitution; or conformably to the constitution, disregarding the law: the court must determine which of these conflicting rules governs the case. This is of the very essence of judicial duty.