In the Marbury v. Madison decision, what was determined regarding the Judiciary Act of 1789?

In the Marbury v. Madison case, the Supreme Court, under Chief Justice John Marshall, determined that the portion of the Judiciary Act of 1789 granting the Supreme Court the power to issue writs of mandamus was unconstitutional. This landmark ruling established the principle of judicial review, allowing the Court to nullify any law that it found to be in conflict with the Constitution.

This decision had significant implications for the balance of power among the branches of government, reinforcing the judiciary's role as a check on legislative and executive actions. The Judiciary Act itself was initially intended to outline the jurisdiction of the federal courts, but the ruling clarified the limits of Congress's legislative power in relation to the Constitution. Thus, the power of the Supreme Court as the interpreter of constitutional law was firmly established, and the Judiciary Act of 1789 was deemed unconstitutional in terms of expanding the Court's original jurisdiction beyond what the Constitution permitted.