Constitutional law is generally the interpretation and application of the United States Constitution, which is the supreme law of the land, and supersedes (preempts) all state laws on matters in which the U.S. Constitution grants the federal government authority. The Constitution is the foundation of the U.S. legal system, and defines (enumerates) the powers of the three branches of government (legislative, executive, and judicial) and each branch’s oversight of the others. The Constitution also defines the relationships between states; between states and the federal government; and between individuals and the state and federal governments.

The Constitution may be amended as provided by Article V, and the first ten amendments were ratified by the states in 1791 and are known as the Bill of Rights.

Constitutional law may also be a reference to state constitutions, but when not specifically indicated, it is considered a reference to the U.S. Constitution.

In Nebraska, as in all states, constitutional law refers to the interpretation and application of the U.S. Constitution, which is the paramount law of the country. The Constitution outlines the powers and functions of the federal government, delineates the separation of powers among the legislative, executive, and judicial branches, and establishes checks and balances to ensure no single branch exceeds its authority. It also governs the relationships between the states, between states and the federal government, and between individuals and both levels of government. When federal and state laws conflict, the Supremacy Clause of the Constitution mandates that federal law prevails. Nebraska's own state constitution operates under the umbrella of the U.S. Constitution and cannot contravene its principles. Amendments to the U.S. Constitution are rare and require a rigorous process as outlined in Article V. The first ten amendments, known as the Bill of Rights, provide a framework for individual liberties and rights. While Nebraska has its own constitution, it must always comply with the U.S. Constitution, which is the ultimate authority on constitutional matters.