What is formed by the decisions of the court system?

The correct choice is case law, which is formed by the decisions made in previous court cases. As judges interpret and apply laws to specific situations, their rulings establish precedents that guide future decisions. This body of law is critical because it provides consistency and predictability in the legal system, allowing individuals and businesses to understand how laws may be applied based on earlier rulings.

While statutory law consists of statutes and regulations passed by legislatures, and administrative law encompasses rules created by administrative agencies, case law specifically arises from judicial interpretations. Common law is a broader term often used synonymously with case law but generally refers to legal principles that evolve from the cumulative decisions of various courts over time, which can include both statutory and case law influences. Thus, case law directly encapsulates the essence of judicial decision-making and its impact on shaping legal standards in society.