What type of law is primarily established through court decisions?

The type of law primarily established through court decisions is common law. Common law evolves from judicial decisions made in court cases, rather than being enacted through legislative statutes. This body of law is developed by judges interpreting statutes and applying legal principles to the facts of cases. Over time, these decisions create precedents that can influence future cases, ensuring consistency and predictability in the legal system.

In contrast, statutory law is created through legislation passed by governmental bodies and is not derived from judicial interpretations. International law governs the relationships between nations and is often established through treaties and agreements rather than court decisions. Regulatory law, while also important, pertains to rules made by governmental agencies based on statutes and does not primarily arise from court decisions. Therefore, common law is the most accurate answer for laws established through court rulings.