What is the supreme law of the land?

The Constitution is the supreme law of the land in the United States. The phrase comes from Article VI, Clause 2, the Supremacy Clause, which declares the Constitution, federal laws made under it, and treaties to be "the supreme Law of the Land," binding on every judge in every state. Drafted in Philadelphia from May to September 1787 by 55 delegates including James Madison, Alexander Hamilton, George Washington, and Benjamin Franklin, it was ratified by the required nine states on June 21, 1788 when New Hampshire signed on, and went into effect on March 4, 1789. With seven articles and 27 amendments, it is the oldest written national constitution still in force anywhere in the world.

Article I creates Congress and lists its enumerated powers, Article II establishes the presidency, Article III sets up the federal judiciary, and Article IV governs relations between the states. Article V provides the amendment process, Article VI contains the Supremacy Clause and bars religious tests for federal office, and Article VII set the rules for ratification. The first ten amendments, the Bill of Rights, were added in 1791 to protect individual liberties from federal overreach.

The Constitution sits above ordinary federal statutes, executive orders, state constitutions, and state laws. When any of those conflict with it, the Constitution wins, and federal courts may strike them down, a power confirmed in Marbury v. Madison in 1803 when Chief Justice John Marshall established judicial review. The Fourteenth Amendment, ratified in 1868, extended most Bill of Rights protections against the states through the doctrine of incorporation that the Supreme Court developed across the twentieth century.

Every president, member of Congress, federal judge, military officer, and naturalizing citizen takes an oath to support and defend this document. For naturalization applicants, recognizing the Constitution as the supreme law signals understanding that no governor, legislature, president, or court can override its rules without going through the Article V amendment process, which requires either a two-thirds vote of both houses of Congress or a convention called by two-thirds of state legislatures, followed by ratification by three-fourths of the states. That high bar is intentional. It forces durable agreement before fundamental rules change, protecting both stability and the rights of political minorities from shifting majorities.