Case law is the set of existing rulings which made new interpretations of law and, therefore, can be cited as precedents. In some countries, such as the USA, the term is exclusively used for judicial decisions of selected appellate courts, courts of first instance, and other bodies discharging judicial functions. In other countries, such as most European countries, the term is applied to any set of rulings on law which is guided by previous rulings, for example, patent office case law. These interpretations are distinguished from statutory law which are the statutes and codes enacted by legislative bodies; regulatory law which are regulations established by governmental agencies based on statutes; and in some states, common law which are the generally accepted laws carried to the colonies and former colonies of England (USA, Australia, etc.). Trials and hearings which are not selected as 'courts of first impression' do not have rulings that become case law; therefore, these rulings cannot be precedents for future court decisions.

Case may refer to:

The Law is a system of rules and guidelines which are enforced through social institutions to govern behavior. Laws are made by governments, specifically by their legislatures. The formation of laws themselves may be influenced by a constitution (written or unwritten) and the rights encoded therein. The law shapes politics, economics and society in countless ways and serves as a social mediator of relations between people.

A general distinction can be made between civil law jurisdictions (including Canon and Socialist law), in which the legislature or other central body codifies and consolidates their laws and common law systems (including Sharia), where judge-made binding precedents are accepted. In some countries, religion may inform the law; for example, in jurisdictions that practice Islamic law, Jewish law or Canon law.

The adjudication of the law is generally divided into two main areas. Criminal law deals with conduct that is designated dishonest by the government and in which the guilty party may be imprisioned or fined. Civil law (not to be confused with civil law jurisdictions above) deals with disputes between individuals or organizations, in which compensation may be awarded to the wronged litigant.