Mandatory authority, unlike persuasive authority, describes legal authority that is binding and must be followed. All mandatory authority are primary sources of law. However, not all primary sources of law are mandatory authority because the jurisdiction affects whether a legal authority is mandatory or persuasive. A secondary source of law can never be mandatory authority.
Mandatory authority consists of constitutions, legislations, and judicial decisions. Constitutions derive their authority from the people, so constitutions bind only those who have agreed to be bound. Thus, while the Constitution of the United States is mandatory authority in every state and every court in the United States, an individual state’s constitution is mandatory authority only within the state’s jurisdiction. In this situation, even though a state constitution is a primary source of law, it is not automatically mandatory authority.
For judicial decisions, vertical stare decisis dictates that judicial decisions by higher courts are mandatory authority for lower courts. Horizontal stare decisis, on the other hand, is generally not binding. The body of binding judicial decisions is specific to a jurisdiction. Therefore, judicial decisions by courts of one jurisdiction are not mandatory authority for courts of another jurisdiction.
[Last updated in August of 2020 by the Wex Definitions Team]