Case law is law that is based on judicial decisions rather than law based on constitutions, statutes, or regulations. Case law concerns unique disputes resolved by courts using the concrete facts of a case. By contrast, statutes and regulations are written abstractly.
Case law, also used interchangeably with common law, refers to the collection of precedents and authority set by previous judicial decisions on a particular issue or topic. In that sense, case law differs from one jurisdiction to another. For example, a case in New York would not be decided using case law from California. Instead, New York courts will analyze the issue relying on binding precedent. If no previous decisions on the issue exist, New York courts might look at precedents from a different jurisdiction, that would be persuasive authority rather than binding authority. Other factors such as how old the decision is and the closeness to the facts will affect the authority of a specific case in common law.
Federalism also plays a major role in determining the authority of case law in a particular court. Indeed, each circuit has its own set of binding case law. As a result, a judgment rendered in the Ninth Circuit will not be binding in the Second Circuit but will have persuasive authority. However, decisions rendered by the Supreme Court of the United States are binding on all federal courts, and on state courts regarding issues of the Constitution and federal law.
[Last updated in May of 2020 by the Wex Definitions Team]