The constitutional doctrine establishes that the Constitution, federal laws, and treaties constitute the supreme law of the land. This principle, articulated in Article VI of the U.S. Constitution, dictates that state judges must adhere to federal law when a conflict arises, even if state laws or constitutions contradict it. A practical example involves federal environmental regulations; if a state law permits a higher level of pollution than federal standards allow, the federal regulations take precedence and the state law is superseded.
The significance of this principle lies in its maintenance of national unity and legal consistency across the states. It ensures that the federal government possesses the necessary authority to enact and enforce laws essential for the nation’s well-being. Historically, it has played a pivotal role in landmark Supreme Court cases, such as McCulloch v. Maryland (1819), which affirmed the power of Congress to establish a national bank and shielded it from state taxation. This clause provides a framework for resolving disputes between federal and state authority, contributing to a more stable and predictable legal environment.