The section of the United States Constitution that assures that federal law is the ultimate law of the land and prevails over state laws is known as the Supremacy Clause. It is found in Article VI, Clause 2 of the Constitution, and states that "this Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the constitution or laws of any state to the contrary notwithstanding."
The Supremacy Clause establishes the authority of federal law over state law, and ensures that federal laws and regulations take precedence over conflicting state laws. It is an important principle of the United States system of federalism, which divides power between the federal government and the states. The Supremacy Clause also applies to treaties made by the United States, which are considered part of the supreme law of the land and must be followed by both federal and state governments.