Case law, often referred to as common law or precedent, is the collection of past legal decisions taken by state and federal judges. In case law, judges render decisions based on the facts of unique cases not covered by federal or state constitutions, statutes, and regulations.
In the United States of America, case law handed down by federal court judges, including the US Courts of Appeals, US District Courts, the US Court of Claims, and the US Court of International Trade and US Bankruptcy Courts, supersedes the dual sovereignty system where decisions are considered binding to all US states. As the US Supreme Court is the highest court in the land, all case law is binding at the federal and state level.
Conversely, case law decided at the state level including State Supreme Courts, Court of Appeals (Appellate Courts) Trial Courts, Circuit Courts and District Courts, are only binding to the state in which that judge presides. In matters of persuasive authority, judges may consider case law delivered in other jurisdictions but are not required to base their decision on this example. For example, a New York District Court may enact persuasive authority to guide the decision based on a similar case in California but is not mandated to deliver the same verdict.