Answer:
Due to establishing the power of Judicial review.
Step-by-step explanation:
William Marbury versus James Madison was very important to the Judicial branch government because it established the power of judicial review for the United states. The great power of Supreme Court is the judicial review. The supreme court has the ability to declare a Executive act in violation of the Constitution. The Court established this judicial review in the case of Marbury v. Madison in the year 1803.