It is emphatically the province and duty of the Judicial Department to say what the law is. How does this excerpt summarize the case? It explains why the Supreme Court ruled in favor of William Marbury in the case of Marbury v. Madison. It explains that the Supreme Court should decide whether a law or action is constitutional. It explains why the judicial department ruled that the Judiciary Act of 1789 was constitutional. It explains that the judicial department has powers that go beyond the limits of the Constitution.