It is emphatically the province and duty of the judicial department to say what the law is...If two laws conflict with each other, the courts must decide on the operation of each...This is of the very essence of judicial duty.
John MarshallThe particular phraseology of the Constitution of the United States confirms and strengthens the principle, supposed to be essential to all written constitutions, that a law repugnant to the Constitution is void; and that courts, as well as other departments, are bound by that instrument.
John MarshallThe federal government is acknowledged by all to be one of enumerated powers. The principle, that it can exercise only the powers granted to it . . . is now universally admitted.
John MarshallCertainly all those who have framed written constitutions contemplate them as forming the fundamental and paramount law of the nation, and consequently the theory of every such government must be, that an act of the legislature, repugnant to the constitution, is void.
John Marshall