Common law is the legal system that develops through judicial decisions rather than legislative statutes. Originating in medieval England, it relies on stare decisis—courts follow precedents set in earlier cases, creating consistent legal rules that evolve gradually.
The American system blends common law with civil law traditions. While legislatures create statutes, courts interpret those statutes and fill gaps through common law principles. Many areas—including contracts, torts, property, and family law—remain primarily common law domains.
Common law develops incrementally as judges resolve specific disputes. Each decision becomes precedent for future cases with similar facts. Higher courts bind lower courts within their jurisdiction. State supreme courts are final authorities on state common law; the U.S. Supreme Court is final on federal common law and constitutional interpretation.
The flexibility allows legal rules to adapt to new circumstances without legislative action. Critics argue this judicial lawmaking lacks democratic legitimacy. Supporters contend it provides stability through precedent while allowing gradual evolution as societal values change.
Common law influences everyday life more than most people realize. Contract principles govern business transactions. Tort law determines compensation for injuries. Property law defines ownership rights. Family law governs marriage, divorce, and child custody—all primarily developed through judicial decisions.