What does constitutional law define in the United States?

Constitutional law in the United States primarily focuses on the structure of the government, outlining the framework within which the government operates. This includes the separation of powers among the three branches—executive, legislative, and judicial—as well as the relationships between the federal government and the states. The U.S. Constitution establishes the authority and limitations of these branches, ensuring a system of checks and balances designed to prevent any single branch from becoming too powerful.

While constitutional law also influences the rights of citizens and can impact international law, its core function is to define how government is organized and how it functions. Therefore, the understanding of constitutional law as the structure of the government is foundational to interpreting all aspects of governance and civic engagement in the U.S.