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 North Dakota, 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 the system of checks and balances. It also governs the relationship between the states and the federal government, as well as between individuals and both levels of government. While the Constitution can be amended through the process outlined in Article V, the first ten amendments, known as the Bill of Rights, provide fundamental protections for individual liberties. North Dakota also has its own state constitution, which operates alongside the U.S. Constitution to govern matters within the state's jurisdiction. However, in cases of conflict between federal and state law, the U.S. Constitution, as interpreted by the courts, takes precedence over state law under the doctrine of federal preemption.