What type of law is established by court decisions rather than through legislative action?

The correct answer is common law, which is developed through the decisions made by judges in court cases rather than being enacted by legislatures. This body of law evolves over time as judges interpret statutes, apply legal principles to unique cases, and establish precedents that guide future court rulings. Common law is distinctively characterized by its reliance on judicial opinions and the doctrine of precedent, where past decisions influence the outcomes of similar cases.

In contrast, international law pertains to agreements and treaties between nations and does not stem from court decisions. Administrative law governs the activities of governmental agencies, the rules and regulations formed by these entities, and is also not derived from court rulings. Constitutional law focuses on the interpretation of a country's constitution and the principles it enshrines, but again, it is not established through court decisions in the same way that common law is. The emphasis on judicial rulings is what sets common law apart and defines its role in the legal system.