Who was the Chief Justice that ruled on the unconstitutionality of the Judiciary Act of 1789?

The Chief Justice who ruled on the unconstitutionality of the Judiciary Act of 1789 was John Marshall. This landmark decision came in the case of Marbury v. Madison in 1803. In this case, Marshall asserted the principle of judicial review, which established the Supreme Court's authority to invalidate laws that conflict with the Constitution. The ruling marked a significant moment in the development of the judicial branch, reinforcing the idea that the Constitution is the supreme law of the land and that it is the duty of the judiciary to uphold that principle.

This case not only invalidated a section of the Judiciary Act of 1789 but also set the precedent for the role of the Supreme Court in interpreting the Constitution and its ability to overturn both state and federal legislation, significantly shaping the balance of power among the branches of government. This decision is a cornerstone of American constitutional law, demonstrating the essential function of the judiciary in maintaining the rule of law.