Final answer:
The source of the excerpt is the landmark Supreme Court case Marbury v. Madison, which established the principle that the Constitution is the supreme law of the land and that any law in conflict with it is void.
Step-by-step explanation:
The excerpt provided offers a significant description of the principles laid down in the landmark Supreme Court case Marbury v. Madison. This case established the doctrine of judicial review, stating that a law that is repugnant or in conflict with the Constitution is void.
The decision, delivered by Chief Justice John Marshall, emphasized that the Constitution is the supreme law of the land and that all legislative acts must conform to it. The ruling enhanced the power of the Judicial Branch by allowing it to declare laws unconstitutional and therefore invalid.
In the Marbury v. Madison case, the justices, through Marshall's persuasive argument, concluded that the Constitution was the 'fundamental and paramount law of the nation.' The Supreme Court declared that the Judiciary Act of 1789 was unconstitutional because it extended the Court's original jurisdiction beyond what the Constitution permitted. Therefore, the assertion that any legislative act contrary to the Constitution is void stems directly from the principles established in Marbury v. Madison.