What document is considered the supreme law of the land in the United States?

The Constitution is considered the supreme law of the land in the United States because it establishes the foundational principles and framework of the U.S. government. It outlines the structure of the government, delineates the powers and responsibilities of various branches, and protects individual rights through amendments. As the highest legal authority, any laws or policies enacted must align with the Constitution; if they do not, they can be deemed unconstitutional and therefore invalid.

In contrast, the Bill of Rights, while crucial as the first ten amendments to the Constitution ensuring individual liberties, is part of the Constitution rather than a standalone document that serves as the supreme law. The Declaration of Independence, though vital in proclaiming the colonies' separation from British rule, does not function as a governing document and does not establish legal frameworks. The Federalist Papers are a series of essays advocating for the ratification of the Constitution and provide insight into the principles of American government, but they are not governing law themselves. Thus, the Constitution holds the highest authority in legal matters in the United States.