John Marshall Vs Thomas Jefferson on Constitutional Interpretation

In Marbury v. Madison (1804), John Marshall argues that the Supreme Court ought to have the authority to determine the constitutionality of laws which come before the court. Since the judges must apply the laws to particular cases, they must necessarily "expound and interpret" those laws. Furthermore, since the Constitution is superior to an ordinary act of the legislature and cannot be annulled by such an act, the judges-when faced with a law contrary to the Constitution-must strike down the law so as to uphold the Constitution. Otherwise, the power of the Constitution itself would be nullified, and the courts would be forced to uphold the very injustices against which the Constitution was meant to protect.

If, for instance, Congress had passed an ex post facto law, and an individual were prosecuted under it before the court, it would defeat the purpose of the Constitution if the court were forced to convict the individual under the law. Marshall emphasizes that court justices take an oath to support the Constitution, and it would thus be immoral for them to violate what they have sworn to support. Those who insist that the courts do not consider the constitutionality of laws in their decisions are in effect insisting that the justices violate their oaths. Furthermore, "the judicial power of the United States is extended to all cases arising under the Constitution," and thus it would absurd for the courts to examine a case arising under the Constitution without examining the instrument under which it arises.