Which document serves as the supreme law of the land?

The U.S. Constitution serves as the supreme law of the land because it establishes the foundational legal framework for the United States government and outlines the rights and responsibilities of its citizens and government institutions. Article VI of the Constitution explicitly states that the Constitution itself, along with federal laws made in accordance with it, constitute the highest legal authority. This principle of supremacy ensures that any law that contradicts the Constitution is considered invalid. The Constitution is a comprehensive document that not only defines the structure of government but also safeguards individual liberties through the Bill of Rights, making it central to American democracy and legal governance.