Some legal rules emerge from decisions rather than from codes. Common law is the body of law developed by judges through written opinions in actual cases, which later courts treat as precedent.

Originating in English royal courts, the common-law method spread to many jurisdictions. Judges reason from earlier holdings, distinguishing or extending them as new facts arise. Statutes can override common-law rules, but where statutes are silent, case law fills the gaps.

Common law emphasizes incremental development and the discipline of reasoned justification. Law students learn it by reading opinions and extracting principles. Even in heavily statutory fields, judicial interpretation continues the common-law style of argument from authority and analogy.

• Law developed through judicial decisions
• Relies on precedent and reasoned opinions
• Can be modified by statutes
• Characteristic of English-derived legal systems